Merge branch 'next' into fix/2137-derive-progress-header-driven

.changeset/2096-eos-antigravity-imperative-adapter.md

@@ -0,0 +1,5 @@
+---
+type: Changed
+pr: 2165
+---
+**Installing GSD into Antigravity now writes the `permissions.allow` rules its CLI documents** — so GSD's own reads and hooks aren't stuck on interactive prompts — and registers GSD's companion MCP server via a standalone `mcp_config.json` (best-effort: Antigravity's raw config schema isn't published, so this uses the Gemini-CLI-successor format). Antigravity's install is now driven by its negotiated capability descriptor instead of hardcoded runtime special-cases. (#2096)

.changeset/2097-eos-augment-imperative-adapter.md

@@ -0,0 +1,6 @@
+---
+type: Changed
+pr: 2166
+---
+
+**Augment Code now installs through its capability descriptor, with a native MCP companion** — installing GSD into Augment registers the GSD companion server in Augment's `settings.json` `mcpServers` and drives command/skill/agent conversion from Augment's negotiated descriptor instead of hardcoded runtime special-cases. (#2097)

.changeset/2098-eos-codebuddy.md

@@ -0,0 +1,6 @@
+---
+type: Changed
+pr: 2169
+---
+
+**CodeBuddy now wires GSD's full extended lifecycle hook set and is driven by its capability descriptor** — installing GSD into CodeBuddy now registers `SubagentStart`, `SubagentStop`, `Stop`, and `PreCompact` hooks in its `settings.json` (it previously had none of these), matching the coverage Qwen/Kimi already ship, and CodeBuddy's install is fully descriptor-driven instead of via residual hardcoded runtime branches. (#2098)

CONTEXT.md

@@ -273,7 +273,7 @@ The `mempalace.memory_mode` config key controlling how authoritative MemPalace i
 Standalone hook-surface writer module extracted from `bin/install.js` as ADR-857 phase 5f-1 (behavior-preserving relocation, no logic change). Owns: Cline rules-body/agents-md/pre-tool-use hook generation (`buildClineRulesBody`, `buildClineAgentsMdBody`, `buildClinePreToolUseHook`, `mergeGsdAgentsMd`, `writeClineArtifacts`); Cursor `hooks.json` lifecycle (`buildCursorHookEntry`, `isManagedCursorHookEntry`, `reconcileCursorHooksJson`, `writeCursorHooksJson`, `removeCursorHooksJson`); Copilot session-hook config (`buildCopilotHookConfig`, `writeCopilotHookConfig`); Codex hook-block and event management (`buildCodexHookBlock`, `rewriteLegacyCodexHookBlock`, `reconcileCodexHooksJsonEvent`, `reconcileCodexHooksJsonSessionStart`, `ensureCodexHooksJsonSessionStart`, `ensureCodexHooksJsonEvent`, `removeCodexHooksJsonEvent`, `removeCodexHooksJsonSessionStart`, `buildCodexHookWindowsShimIR`); Kimi native config.toml `[[hooks]]` lifecycle (`buildKimiHooksTomlBlock`, `stripKimiHooksTomlBlock`, `writeKimiHooksToml`, `removeKimiHooksToml` — #2095 EoS/kimi Upgrade 1, the first genuinely NEW hook surface added post-relocation rather than a behavior-preserving move: kimi's `[[hooks]]` array lives in its own native `config.toml`, resolved by `resolveKimiHooksTomlDir` in Runtime Homes Module to a directory deliberately separate from kimi's GSD configDir, wrapped in `# GSD Hooks BEGIN`/`END` marker comments for idempotent reinstall); and shared hook command helpers (`buildHookCommand`, `rewriteLegacyManagedNodeHookCommands`, `normalizeNodePath`, `resolveNodeRunner`). `bin/install.js` delegates to this module via thin wrappers and re-exports its functions unchanged so existing tests require no modification. Source: `src/runtime-hooks-surface.cts`. Built output: `gsd-core/bin/lib/runtime-hooks-surface.cjs`.
 
 ### Runtime Config Adapter Registry
-Module owning the explicit per-runtime config-mutation dispatch table for the installer. `resolveRuntimeConfigIntent(runtime)` projects a typed config intent — `installSurface` (`settings-json` | `codex-toml` | `copilot-instructions` | `cline-rules` | `cursor-hooks-json` | `profile-marker-only`), `writesSharedSettings` (the `finishInstall` shared-settings write gate), and `finishPermissionWriter` (`opencode` | `kilo` | none) — that `bin/install.js` dispatches on instead of inline `runtime === '...'` branching. Owns adapter selection only: it performs no filesystem IO and does not execute config mutations (the install/finishInstall handlers and the per-runtime writers do that). Unknown runtimes fail loudly with a `TypeError`, guarded by an `Object.hasOwn` own-property check so prototype-chain keys (`__proto__`, `constructor`) also throw. Also exports `resolveInstallPlan(runtime)` — the ADR-58 `InstallPlan` capstone — which collects the install-level descriptor axes (`installSurface`, `writesSharedSettings`, `finishPermissionWriter`, `hookEvents`, `extendedHookEvents`, `hooksSurface`, `sandboxTier`) into one typed `InstallPlan` value consumed by `install()` and `finishInstall()` in `bin/install.js`. `sandboxTier` (`none` | `codex-agent-sandbox`) gates per-agent `sandbox_mode` emission in the codex TOML path and fails loud on a missing/invalid value (#1151). The spatial axes (`configHome`, `artifactLayout`, `commandStyle`) remain behind their self-resolving adapter modules and are not part of the plan; they are the execution adapters. Realizes both the adapter-selection and plan-collection halves of the Runtime Install Policy Module boundary. Source: `gsd-core/bin/lib/runtime-config-adapter-registry.cjs`. See ADR-58, #60.
+Module owning the explicit per-runtime config-mutation dispatch table for the installer. `resolveRuntimeConfigIntent(runtime)` projects a typed config intent — `installSurface` (`settings-json` | `codex-toml` | `copilot-instructions` | `cline-rules` | `cursor-hooks-json` | `profile-marker-only`), `writesSharedSettings` (the `finishInstall` shared-settings write gate), and `finishPermissionWriter` (`opencode` | `kilo` | `antigravity` | none) — that `bin/install.js` dispatches on instead of inline `runtime === '...'` branching. Owns adapter selection only: it performs no filesystem IO and does not execute config mutations (the install/finishInstall handlers and the per-runtime writers do that). Unknown runtimes fail loudly with a `TypeError`, guarded by an `Object.hasOwn` own-property check so prototype-chain keys (`__proto__`, `constructor`) also throw. Also exports `resolveInstallPlan(runtime)` — the ADR-58 `InstallPlan` capstone — which collects the install-level descriptor axes (`installSurface`, `writesSharedSettings`, `finishPermissionWriter`, `hookEvents`, `extendedHookEvents`, `hooksSurface`, `sandboxTier`) into one typed `InstallPlan` value consumed by `install()` and `finishInstall()` in `bin/install.js`. `sandboxTier` (`none` | `codex-agent-sandbox`) gates per-agent `sandbox_mode` emission in the codex TOML path and fails loud on a missing/invalid value (#1151). The spatial axes (`configHome`, `artifactLayout`, `commandStyle`) remain behind their self-resolving adapter modules and are not part of the plan; they are the execution adapters. Realizes both the adapter-selection and plan-collection halves of the Runtime Install Policy Module boundary. Source: `gsd-core/bin/lib/runtime-config-adapter-registry.cjs`. See ADR-58, #60.
 
 ### Claude Code Plugin Manifest Module
 Module owning the projection of gsd-core's artifact surfaces (`commands`, `agents`, hooks) onto the Claude Code plugin contract (`.claude-plugin/plugin.json` + `hooks/hooks.json`) — the plugin-contract sibling of the Runtime Artifact Layout Module (which projects the same surfaces onto filesystem placements). Defined mapping: `name`=`binName` (drives the `/gsd-core:` command namespace), `repository`/`homepage`=`repoUrl` (Package Identity Module), `version`/`description`/`license` from `package.json` (`version` is required for `claude plugin validate --strict`), `commands`=`./commands/gsd/`, agents via Claude Code's default `agents/` discovery (the explicit string form is schema-rejected), `hooks`=`./hooks/hooks.json`. The hook projection carries ONLY the always-on subset of the Installer Module's Claude `settings.json` wiring (check-update, context-monitor, prompt-guard, read-guard, worktree-path-guard, read-injection-scanner) via `${CLAUDE_PLUGIN_ROOT}`; config-gated opt-in hooks are excluded because a static manifest cannot honor per-project config gates, and plugin-shipped agents cannot carry hook frontmatter (so all plugin-path hook wiring lives in hooks.json). `hooks.json` covers all seven Claude Code lifecycle events: SessionStart, PreToolUse, PostToolUse, SubagentStop, Stop, PreCompact (all wired to context-monitor for context-headroom awareness), and FileChanged (matcher: `config.json` → config-reload, injects `additionalContext` when `.planning/config.json` changes mid-session). Additive — the file-copy path (Runtime Artifact Layout / Install Policy / Installer Modules) is unchanged. Conformance is validated by `claude plugin validate --strict` plus the in-repo drift-guard `tests/issue-766-plugin-manifest.test.cjs`. _Avoid_: "the plugin API", "the plugin file" (when you mean the seam). See ADR-766 and Runtime Artifact Layout Module.

bin/install.js

@@ -386,6 +386,12 @@ const FALLBACK_HOST_BEHAVIORS = Object.freeze({
     legacyCommandsGsdInstallMigration: true,
     legacyCommandsGsdUninstall: 'global',
   }),
+  // antigravity's global config dir is resolved dynamically (env-overridable,
+  // multi-segment) via resolveAntigravityGlobalDir in getConfigDirFromHome. If the
+  // registry fails to load, this floor keeps that routing intact instead of
+  // silently falling through to the generic getGlobalConfigHomeFragment default
+  // (which would return the wrong '.claude' fragment). (ADR-1239 / #2096)
+  antigravity: Object.freeze({ globalDirResolver: 'antigravity' }),
 });
 
 /**
@@ -640,7 +646,15 @@ function getConfigDirFromHome(runtime, isGlobal) {
   // multi-segment via resolveAntigravityGlobalDir + path.relative) — not a table
   // entry. (The prior inner `if (!isGlobal) return "'.agents'"` was unreachable:
   // !isGlobal returns at the top of this function.)
-  if (runtime === 'antigravity') {
+  // Descriptor-driven (ADR-1239 / #2096): folded from a hardcoded
+  // `runtime === 'antigravity'` literal into a read of the runtime's
+  // `hostBehaviors.globalDirResolver` descriptor field (via _hostBehaviors, which
+  // also degrades to FALLBACK_HOST_BEHAVIORS on registry-load failure). This is
+  // antigravity-unique: unlike `configHome.kind === 'dot-home-nested'` (which
+  // windsurf also declares — see capabilities/windsurf/capability.json — and
+  // would wrongly route windsurf's global dir through
+  // resolveAntigravityGlobalDir), `globalDirResolver` is only set by antigravity.
+  if (_hostBehaviors(runtime).globalDirResolver === 'antigravity') {
     const antigravityDir = resolveAntigravityGlobalDir();
     const rel = path.relative(os.homedir(), antigravityDir);
     const segments = rel.split(path.sep).filter(Boolean);
@@ -2592,14 +2606,6 @@ function convertClaudeAgentToWindsurfAgent(content) {
 // Augment uses a tool set similar to Cursor/Windsurf.
 // Config lives in .augment/ (local) and ~/.augment/ (global).
 
-const claudeToAugmentTools = {
-  Bash: 'launch-process',
-  Edit: 'str-replace-editor',
-  AskUserQuestion: null,
-  SlashCommand: null,
-  TodoWrite: 'add_tasks',
-};
-
 // #1675 (ADR-1508): the augment converter family below was a byte-identical
 // duplicate of runtime-artifact-conversion.cjs:
 //   convertSlashCommandsToAugmentSkillMentions, convertClaudeToAugmentMarkdown,
@@ -6843,7 +6849,9 @@ function uninstall(isGlobal, runtime = DEFAULT_RUNTIME) {
   // skipSharedHooksInstall fold (was never referenced here besides the
   // destructure). #2095: isKimi likewise dropped — kimi is now a hooks/
   // consumer, so its former `&& !isKimi` uninstall guards were removed.
-  const { isOpencode, isCodex, isCopilot, isAntigravity, isCursor, isWindsurf, isAugment, isQwen, isHermes, isCodebuddy, isCline } = runtimeFlags(runtime);
+  // #2096: isAntigravity dropped — unused in this function.
+  // #2098: isCodebuddy dropped — unused in this function.
+  const { isOpencode, isCodex, isCopilot, isCursor, isWindsurf, isAugment, isQwen, isHermes, isCline } = runtimeFlags(runtime);
   const dirName = getDirName(runtime);
 
   // Get the target directory based on runtime and install type. Cline local
@@ -7505,6 +7513,47 @@ function uninstall(isGlobal, runtime = DEFAULT_RUNTIME) {
       }
     }
 
+    // #2096 Phase B Upgrade 1 — Remove GSD-owned Antigravity permissions.allow
+    // rules from settings.json. Symmetric to the Claude branch above: filters
+    // only the exact GSD-owned rule strings (regenerated from the current
+    // configDir) to preserve any user-added allow entries and all deny/ask.
+    if (resolveInstallPlan(runtime).finishPermissionWriter === 'antigravity' && settings.permissions) {
+      let antigravityPermissionsModified = false;
+      if (Array.isArray(settings.permissions.allow)) {
+        const gsdRules = new Set(buildAntigravityAllowRules(targetDir));
+        const before = settings.permissions.allow.length;
+        settings.permissions.allow = settings.permissions.allow.filter((e) => !gsdRules.has(e));
+        if (settings.permissions.allow.length !== before) {
+          antigravityPermissionsModified = true;
+        }
+        if (settings.permissions.allow.length === 0) {
+          delete settings.permissions.allow;
+        }
+      }
+      if (Object.keys(settings.permissions).length === 0) {
+        delete settings.permissions;
+      }
+      if (antigravityPermissionsModified) {
+        settingsModified = true;
+        console.log(`  ${green}✓${reset} Removed GSD permissions from settings.json`);
+      }
+    }
+
+    // #2097 UPGRADE 3 — Remove the MCP companion entry from settings.json for
+    // runtimes that host MCP there (Augment), symmetric to the mcp_config.json
+    // removal for Antigravity below. Only the GSD-owned mcpServers.gsd key is
+    // removed — any other user-configured MCP servers are preserved.
+    if (_hostBehaviors(runtime).mcpCompanion === 'settings-json' &&
+      settings.mcpServers && typeof settings.mcpServers === 'object' &&
+      settings.mcpServers.gsd !== undefined) {
+      delete settings.mcpServers.gsd;
+      if (Object.keys(settings.mcpServers).length === 0) {
+        delete settings.mcpServers;
+      }
+      settingsModified = true;
+      console.log(`  ${green}✓${reset} Removed GSD MCP companion server from settings.json`);
+    }
+
     if (settingsModified) {
       writeSettings(settingsPath, settings);
       removedCount++;
@@ -7595,6 +7644,29 @@ function uninstall(isGlobal, runtime = DEFAULT_RUNTIME) {
     }
   }
 
+  // 8. For Antigravity, remove the MCP companion entry from mcp_config.json
+  // (#2096 Phase B Upgrade 2). Only the GSD-owned mcpServers.gsd key is
+  // removed — any other user-configured MCP servers are preserved.
+  if (resolveInstallPlan(runtime).finishPermissionWriter === 'antigravity') {
+    const mcpConfigPath = path.join(targetDir, 'mcp_config.json');
+    if (fs.existsSync(mcpConfigPath)) {
+      try {
+        const mcpConfig = JSON.parse(fs.readFileSync(mcpConfigPath, 'utf8'));
+        if (mcpConfig && typeof mcpConfig === 'object' && mcpConfig.mcpServers && mcpConfig.mcpServers.gsd !== undefined) {
+          delete mcpConfig.mcpServers.gsd;
+          if (Object.keys(mcpConfig.mcpServers).length === 0) {
+            delete mcpConfig.mcpServers;
+          }
+          fs.writeFileSync(mcpConfigPath, JSON.stringify(mcpConfig, null, 2) + '\n');
+          removedCount++;
+          console.log(`  ${green}✓${reset} Removed GSD MCP companion server from mcp_config.json`);
+        }
+      } catch (e) {
+        // Ignore JSON parse errors
+      }
+    }
+  }
+
   // Remove the file manifest that the installer wrote at install time.
   // Without this step the metadata file persists after uninstall (#1908).
   const manifestPath = path.join(targetDir, MANIFEST_NAME);
@@ -7848,6 +7920,193 @@ function configureKiloPermissions(isGlobal = true, configDir = null) {
   console.log(`  ${green}✓${reset} Configured read permission for GSD docs`);
 }
 
+/**
+ * Convert an absolute path to a `~`-relative form when it lives under the
+ * user's home directory (generalizes configureKiloPermissions'
+ * single-default-dir shorthand to Antigravity's three probed sibling config
+ * dirs — antigravity/antigravity-ide/antigravity-cli under ~/.gemini — none of
+ * which is a single fixed "default").
+ */
+function toTildePosixPath(absPath) {
+  const posixPath = absPath.replace(/\\/g, '/');
+  const posixHome = os.homedir().replace(/\\/g, '/');
+  return posixPath === posixHome || posixPath.startsWith(`${posixHome}/`)
+    ? `~${posixPath.slice(posixHome.length)}`
+    : posixPath;
+}
+
+/**
+ * Antigravity permission rule strings this installer contributes.
+ * Schema: antigravity.google/docs/cli/permissions — "action(target)" rule
+ * strings in permissions.{allow,deny,ask}, evaluated deny > ask > allow. GSD
+ * only ever contributes to `allow` — never deny/ask (those are user-owned risk
+ * decisions this installer has no business making).
+ */
+function buildAntigravityAllowRules(configDir) {
+  const gsdPath = toTildePosixPath(configDir);
+  return [
+    `read_file(${gsdPath}/gsd-core/*)`,
+    `read_file(${gsdPath}/agents/gsd-*)`,
+    `read_file(${gsdPath}/skills/gsd-*)`,
+    `command(node ${gsdPath}/hooks/*)`,
+  ];
+}
+
+/**
+ * Configure Antigravity permissions to allow reading/executing GSD's installed
+ * tree without per-call approval prompts (#2096 Phase B Upgrade 1 — mirrors
+ * configureKiloPermissions/configureOpencodePermissions).
+ *
+ * Antigravity's permission schema (antigravity.google/docs/cli/permissions) is
+ * `{"permissions":{"allow":[...],"deny":[...],"ask":[...]}}`, living in the
+ * SAME settings.json GSD's own hook registration writes for this runtime
+ * (installSurface: 'settings-json', writesSharedSettings: true) — unlike
+ * Kilo/OpenCode, which write a separate native config file. This function
+ * re-reads the file (already containing GSD's hooks by the time finishInstall
+ * reaches this call) and only appends to permissions.allow.
+ *
+ * Non-destructive + idempotent: only `permissions.allow` is touched; an
+ * existing user permissions block (including any deny/ask entries, or
+ * unrelated allow entries) is preserved untouched.
+ *
+ * @param {boolean} isGlobal - Whether this is a global or local install
+ * @param {string|null} configDir - Resolved config directory when already known
+ */
+function configureAntigravityPermissions(isGlobal = true, configDir = null) {
+  // For local installs, use ./.agents/ (GSD's antigravity localConfigDir)
+  // For global installs, use the resolved ~/.gemini/antigravity{,-ide,-cli}
+  const antigravityConfigDir = configDir || (isGlobal
+    ? getGlobalConfigDir('antigravity', explicitConfigDir)
+    : path.join(process.cwd(), '.agents'));
+  // Ensure config directory exists
+  fs.mkdirSync(antigravityConfigDir, { recursive: true });
+
+  const configPath = path.join(antigravityConfigDir, 'settings.json');
+
+  // Read existing settings.json (readSettings tolerates JSONC + missing file;
+  // returns null — and warns — only when the file exists but fails to parse).
+  const config = readSettings(configPath);
+  if (config === null) {
+    // Cannot parse — DO NOT overwrite user's config (readSettings already warned).
+    return;
+  }
+
+  // Ensure permission structure exists
+  if (!config.permissions || typeof config.permissions !== 'object' || Array.isArray(config.permissions)) {
+    config.permissions = {};
+  }
+  if (!Array.isArray(config.permissions.allow)) {
+    config.permissions.allow = [];
+  }
+
+  let modified = false;
+  for (const rule of buildAntigravityAllowRules(antigravityConfigDir)) {
+    if (!config.permissions.allow.includes(rule)) {
+      config.permissions.allow.push(rule);
+      modified = true;
+    }
+  }
+
+  if (!modified) {
+    return; // Already configured
+  }
+
+  writeSettings(configPath, config);
+  console.log(`  ${green}✓${reset} Configured Antigravity permissions for GSD paths`);
+}
+
+/**
+ * Configure Antigravity's MCP companion server config (#2096 Phase B
+ * Upgrade 2).
+ *
+ * Antigravity CLI manages MCP servers via standalone `mcp_config.json`
+ * profiles rather than nesting them in settings.json (antigravity.google/docs/
+ * cli/gcli-migration: "Antigravity CLI uses standalone mcp_config.json
+ * profiles in ~/.gemini/config/ for global servers and .agents/mcp_config.json
+ * for workspace servers"). The raw schema for the Antigravity IDE surface
+ * itself is unpublished (docs are JS-rendered), so this follows the CLI's
+ * documented standalone-profile convention plus the standard Gemini/MCP
+ * `mcpServers` shape.
+ *
+ * BEST-EFFORT PATH CHOICE: rather than the CLI doc's separate `~/.gemini/config/`
+ * directory for global scope, this writes `<configDir>/mcp_config.json` — the
+ * SAME resolved configDir as settings.json (configureAntigravityPermissions) —
+ * because (1) GSD's own antigravity configDir resolution already varies
+ * per-user across three sibling dirs (antigravity/antigravity-ide/
+ * antigravity-cli — see resolveAntigravityGlobalDir), so a hardcoded separate
+ * shared path would not track that resolution, and (2) it matches the doc's
+ * OWN workspace-scope convention exactly (`.agents/mcp_config.json`, which IS
+ * GSD's local configDir for antigravity), keeping global/local symmetric and
+ * consistent with the configDir-relative convention every other GSD
+ * permission writer (kilo/opencode) already uses.
+ *
+ * Non-destructive + idempotent: only adds mcpServers.gsd when entirely absent;
+ * any other user-configured mcpServers entries (or a user's OWN "gsd" override)
+ * are preserved untouched (Hyrum's Law — mirrors OpenCode's config.mcp.gsd guard).
+ *
+ * @param {boolean} isGlobal - Whether this is a global or local install
+ * @param {string|null} configDir - Resolved config directory when already known
+ */
+function configureAntigravityMcpConfig(isGlobal = true, configDir = null) {
+  const antigravityConfigDir = configDir || (isGlobal
+    ? getGlobalConfigDir('antigravity', explicitConfigDir)
+    : path.join(process.cwd(), '.agents'));
+  fs.mkdirSync(antigravityConfigDir, { recursive: true });
+
+  const configPath = path.join(antigravityConfigDir, 'mcp_config.json');
+
+  let config = {};
+  if (fs.existsSync(configPath)) {
+    try {
+      const parsed = JSON.parse(fs.readFileSync(configPath, 'utf8'));
+      config = (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) ? parsed : {};
+    } catch (e) {
+      // Cannot parse - DO NOT overwrite user's config
+      console.log(`  ${yellow}⚠${reset} Could not parse mcp_config.json - skipping MCP companion config`);
+      console.log(`    ${dim}Reason: ${e.message}${reset}`);
+      console.log(`    ${dim}Your config was NOT modified. Fix the syntax manually if needed.${reset}`);
+      return;
+    }
+  }
+
+  if (!config.mcpServers || typeof config.mcpServers !== 'object' || Array.isArray(config.mcpServers)) {
+    config.mcpServers = {};
+  }
+
+  if (config.mcpServers.gsd !== undefined) {
+    return; // Already configured (or a user-owned override) — never clobber.
+  }
+
+  config.mcpServers.gsd = {
+    command: 'npx',
+    args: ['-y', '-p', PACKAGE_NAME, 'gsd-mcp-server'],
+  };
+
+  fs.writeFileSync(configPath, JSON.stringify(config, null, 2) + '\n');
+  console.log(`  ${green}✓${reset} Configured Antigravity MCP companion server (gsd)`);
+}
+
+/**
+ * #2097 (ADR-1239 transport:mcp): register the GSD companion MCP server inside a
+ * runtime's settings.json (Augment hosts MCP in settings.json.mcpServers, unlike
+ * Antigravity's standalone mcp_config.json). Mutates the in-memory settings object
+ * that finishInstall already writes — non-destructive + idempotent: only sets
+ * mcpServers.gsd, preserving any user-defined servers (a user's own `gsd` override
+ * is respected — Hyrum's Law).
+ * @param {object} settings - the in-memory settings object finishInstall will write
+ */
+function mergeGsdMcpServerIntoSettings(settings) {
+  if (!settings.mcpServers || typeof settings.mcpServers !== 'object' || Array.isArray(settings.mcpServers)) {
+    settings.mcpServers = {};
+  }
+  if (settings.mcpServers.gsd === undefined) {
+    settings.mcpServers.gsd = {
+      command: 'npx',
+      args: ['-y', '-p', PACKAGE_NAME, 'gsd-mcp-server'],
+    };
+  }
+}
+
 /**
  * Verify a directory exists and contains files
  */
@@ -7962,7 +8221,9 @@ function writeManifest(configDir, runtime = DEFAULT_RUNTIME, options = {}) {
   // above, now covered by hostBehaviors.skipSharedHooksInstall.
   // #2095: isKimi dropped — kimi is now a hooks/ consumer like every other
   // settings-json-adjacent runtime, so the `&& !isKimi` term below was removed.
-  const { isOpencode, isCodex, isCopilot, isAntigravity, isCursor, isWindsurf, isAugment, isQwen, isHermes, isCodebuddy, isCline } = runtimeFlags(runtime);
+  // #2096: isAntigravity dropped — unused in this function.
+  // #2098: isCodebuddy dropped — unused in this function.
+  const { isOpencode, isCodex, isCopilot, isCursor, isWindsurf, isAugment, isQwen, isHermes, isCline } = runtimeFlags(runtime);
   const gsdDir = path.join(configDir, 'gsd-core');
   // #1367: Claude local now writes flat gsd-*.md files at commands/ (not commands/gsd/).
   // Claude local uses flatCommandsDir instead for manifest recording.
@@ -8469,7 +8730,15 @@ function install(isGlobal, runtime = DEFAULT_RUNTIME, options = {}) {
   // below were removed, leaving isKimi unused in this function (the kimi
   // local-install-deferred branch above already reads
   // _hostBehaviors(runtime).localInstallDeferred instead of this flag).
-  const { isOpencode, isZcode, isCodex, isCopilot, isAntigravity, isCursor, isWindsurf, isAugment, isTrae, isQwen, isHermes, isCodebuddy, isCline } = runtimeFlags(runtime);
+  // #2096: isAntigravity dropped — antigravity is in
+  // _DESCRIPTOR_AGENTS_RUNTIMES below, so its two legacy-agent-loop branches
+  // (the path-rewrite skip and the converter dispatch) were unreachable dead
+  // code; both were removed rather than re-gated on hostBehaviors.
+  // #2098: isCodebuddy dropped — codebuddy is also in
+  // _DESCRIPTOR_AGENTS_RUNTIMES below, so its legacy converter-dispatch branch
+  // (the `isCodebuddy` arm calling convertClaudeAgentToCodebuddyAgent) was
+  // unreachable dead code and was removed rather than re-gated.
+  const { isOpencode, isZcode, isCodex, isCopilot, isCursor, isWindsurf, isAugment, isTrae, isQwen, isHermes, isCline } = runtimeFlags(runtime);
   const plan = resolveInstallPlan(runtime);
   const dirName = getDirName(runtime);
   const src = path.join(__dirname, '..');
@@ -9088,22 +9357,6 @@ function install(isGlobal, runtime = DEFAULT_RUNTIME, options = {}) {
           failures.push('commands/gsd-*');
         }
       }
-
-      // CodeBuddy only: also report the commands/ output (#789 — slash commands)
-      if (isCodebuddy) {
-        const commandsDir = path.join(targetDir, 'commands');
-        if (fs.existsSync(commandsDir)) {
-          const cmdCount = fs.readdirSync(commandsDir)
-            .filter(f => f.startsWith('gsd-') && f.endsWith('.md')).length;
-          if (cmdCount > 0) {
-            console.log(`  ${green}✓${reset} Installed ${cmdCount} slash commands to commands/`);
-          } else {
-            failures.push('commands/gsd-*');
-          }
-        } else {
-          failures.push('commands/gsd-*');
-        }
-      }
     }
   } else if (_hostBehaviors(runtime).localCommandsViaRules) {
     // Cline local install: rules-based only — commands are embedded in .clinerules (generated below).
@@ -9351,7 +9604,11 @@ function install(isGlobal, runtime = DEFAULT_RUNTIME, options = {}) {
         const bareDirRegex = /~\/\.claude\b/g;
         const bareHomeDirRegex = /\$HOME\/\.claude\b/g;
         const normalizedPathPrefix = pathPrefix.replace(/\/$/, '');
-        if (!isCopilot && !isAntigravity) {
+        // #2096: `&& !isAntigravity` dropped — antigravity is in
+        // _DESCRIPTOR_AGENTS_RUNTIMES above, so this whole branch is already
+        // unreachable for it; the path-rewrite skip for antigravity now lives
+        // in the descriptor-driven `applyAgentPathRewrites` (hostBehaviors.noPathRewrite).
+        if (!isCopilot) {
           content = content.replace(dirRegex, pathPrefix);
           content = content.replace(homeDirRegex, pathPrefix);
           content = content.replace(bareDirRegex, normalizedPathPrefix);
@@ -9402,16 +9659,8 @@ function install(isGlobal, runtime = DEFAULT_RUNTIME, options = {}) {
           content = convertClaudeAgentToCodexAgent(content);
         } else if (isCopilot) {
           content = convertClaudeAgentToCopilotAgent(content, isGlobal);
-        } else if (isAntigravity) {
-          content = convertClaudeAgentToAntigravityAgent(content, isGlobal);
         } else if (isWindsurf) {
           content = convertClaudeAgentToWindsurfAgent(content);
-        } else if (isAugment) {
-          content = convertClaudeAgentToAugmentAgent(content);
-        } else if (isTrae) {
-          content = convertClaudeAgentToTraeAgent(content);
-        } else if (isCodebuddy) {
-          content = convertClaudeAgentToCodebuddyAgent(content);
         } else if (_hostBehaviors(runtime).frontmatterDialect === 'cline') {
           // Descriptor-driven (ADR-1239 / #2090): folded from `isCline` into
           // hostBehaviors.frontmatterDialect === 'cline'.
@@ -10437,7 +10686,10 @@ function install(isGlobal, runtime = DEFAULT_RUNTIME, options = {}) {
   // Claude Code sets $CLAUDE_PROJECT_DIR; Antigravity does not — and on
   // Windows its own substitution logic doubles the path (#2557). It runs
   // project hooks with the project dir as cwd, so bare relative paths work.
-  const localPrefix = projectLocalHookPrefix({ runtime, dirName });
+  // Descriptor-driven (ADR-1239 / #2096): hookPathStyle comes from the
+  // runtime's hostBehaviors instead of a hardcoded `runtime === 'antigravity'`
+  // check inside projectLocalHookPrefix.
+  const localPrefix = projectLocalHookPrefix({ runtime, dirName, hookPathStyle: _hostBehaviors(runtime).hookPathStyle });
   const hookOpts = { portableHooks: hasPortableHooks, runtime };
   // #2979: local-install hook commands also use the absolute node path so
   // GUI/minimal-PATH runtimes can resolve them. Bare `node` fails when the
@@ -10615,7 +10867,9 @@ function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallS
   // #2094: isTrae dropped — unused in this function.
   // #2095: isKimi dropped — the Kimi "Done!" banner below reads
   // _hostBehaviors(runtime).doneBannerStyle === 'kimi-agent-file' (descriptor-driven), not this flag.
-  const { isOpencode, isCodex, isCopilot, isAntigravity, isCursor, isWindsurf, isAugment, isQwen, isHermes, isCodebuddy, isCline } = runtimeFlags(runtime);
+  // #2096: isAntigravity dropped — unused in this function.
+  // #2098: isCodebuddy dropped — unused in this function.
+  const { isOpencode, isCodex, isCopilot, isCursor, isWindsurf, isAugment, isQwen, isHermes, isCline } = runtimeFlags(runtime);
   const plan = resolveInstallPlan(runtime);
 
   if (shouldInstallStatusline && plan.writesSharedSettings && !_hostBehaviors(runtime).skipSettingsUi) {
@@ -10677,6 +10931,12 @@ function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallS
     mergeClaudePermissions(settings);
   }
 
+  // #2097 UPGRADE 3 (transport:mcp): companion MCP server for runtimes that host
+  // MCP in settings.json (Augment). settings.json is golden-excluded, so no golden change.
+  if (_hostBehaviors(runtime).mcpCompanion === 'settings-json' && settings && plan.writesSharedSettings) {
+    mergeGsdMcpServerIntoSettings(settings);
+  }
+
   // Write settings when runtime supports settings.json.
   // #3002 CR: defense-in-depth — re-run validateHookFields right before
   // serialization. The push-site guards above already skip null-command
@@ -10698,6 +10958,15 @@ function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallS
     configureKiloPermissions(isGlobal, configDir);
   }
 
+  // Configure Antigravity permissions + MCP companion server (#2096 Phase B
+  // Upgrades 1+2). Not GSD_TEST_MODE-gated — mirrors Kilo's dispatch exactly;
+  // both writers target files (settings.json, mcp_config.json) scoped under
+  // this runtime's own configDir, so they are safe to run unconditionally.
+  if (plan.finishPermissionWriter === 'antigravity') {
+    configureAntigravityPermissions(isGlobal, configDir);
+    configureAntigravityMcpConfig(isGlobal, configDir);
+  }
+
   // For non-Claude runtimes, DEFAULT resolve_model_ids to "omit" in ~/.gsd/defaults.json
   // when it is absent or falsy, so resolveModelInternal() returns '' instead of Claude
   // aliases (opus/sonnet/haiku) the runtime can't resolve. An explicit `true` opt-in
@@ -11675,6 +11944,13 @@ module.exports = {
     getConfigDirFromHome,
     resolveKiloConfigPath,
     configureKiloPermissions,
+    // #2096 Phase B Upgrades 1+2 — Antigravity permission-writer + MCP companion
+    toTildePosixPath,
+    buildAntigravityAllowRules,
+    configureAntigravityPermissions,
+    configureAntigravityMcpConfig,
+    // #2097 UPGRADE 3 — Augment MCP companion (settings.json-hosted)
+    mergeGsdMcpServerIntoSettings,
     claudeToCopilotTools,
     convertCopilotToolName,
     convertClaudeToCopilotContent,

capabilities/antigravity/capability.json

@@ -71,7 +71,7 @@
     "supportTier": 1,
     "installSurface": "settings-json",
     "writesSharedSettings": true,
-    "permissionWriter": null,
+    "permissionWriter": "antigravity",
     "extendedHookEvents": [],
     "hostIntegration": {
       "embeddingMode": "declarative",
@@ -81,7 +81,7 @@
         "nested": "undocumented",
         "maxDepth": "undocumented",
         "background": true,
-        "subagentToolkit": "undocumented",
+        "subagentToolkit": "full",
         "backgroundDispatch": "undocumented"
       },
       "modelMode": "passive",
@@ -91,7 +91,11 @@
       "runtime": "go"
     },
     "hostBehaviors": {
-      "reviewerCli": true
+      "reviewerCli": true,
+      "projectInstructionFile": "GEMINI.md",
+      "noPathRewrite": true,
+      "hookPathStyle": "raw",
+      "globalDirResolver": "antigravity"
     }
   }
 }

capabilities/augment/capability.json

@@ -82,6 +82,10 @@
     "writesSharedSettings": true,
     "permissionWriter": null,
     "extendedHookEvents": [],
+    "hostBehaviors": {
+      "commandBodyConverter": "convertClaudeToAugmentMarkdown",
+      "mcpCompanion": "settings-json"
+    },
     "hostIntegration": {
       "embeddingMode": "declarative",
       "commandSurface": "slash-file",

capabilities/codebuddy/capability.json

@@ -81,7 +81,12 @@
     "installSurface": "settings-json",
     "writesSharedSettings": true,
     "permissionWriter": null,
-    "extendedHookEvents": [],
+    "extendedHookEvents": [
+      "SubagentStop",
+      "Stop",
+      "PreCompact",
+      "SubagentStart"
+    ],
     "hostIntegration": {
       "embeddingMode": "declarative",
       "commandSurface": "slash-file",
@@ -98,6 +103,9 @@
       "stateIO": "filesystem",
       "transport": "mcp",
       "runtime": "node"
+    },
+    "hostBehaviors": {
+      "reportCommandsDir": true
     }
   }
 }

docs/adr/1016-runtime-capability-descriptor.md

@@ -116,9 +116,9 @@ Selects which config-writing adapter `resolveRuntimeConfigIntent` (in `runtime-c
 
 Whether the runtime writes a shared `settings.json`. Replaces the former inline boolean per runtime in `runtime-config-adapter-registry`. Together with `installSurface` this fully parameterises the adapter-selection path.
 
-#### `permissionWriter` — `null | 'opencode' | 'kilo'`
+#### `permissionWriter` — `null | 'opencode' | 'kilo' | 'antigravity'`
 
-The finish-time permissions-sidecar writer (the JSONC file opencode and kilo require). Replaces the old `finishPermissionWriter` field in the `runtime-config-adapter-registry` `REGISTRY` table. All 14 runtimes that write no permissions sidecar carry `null`.
+The finish-time permissions-sidecar writer. `opencode`/`kilo` write a dedicated JSONC config file; `antigravity` (#2096 Phase B Upgrade 1) instead merges a `permissions.allow` array into the SAME shared `settings.json` GSD's own hook registration writes, plus a standalone `mcp_config.json` MCP-companion profile (Upgrade 2, dispatched alongside it). Replaces the old `finishPermissionWriter` field in the `runtime-config-adapter-registry` `REGISTRY` table. All 13 runtimes that write no permissions sidecar carry `null`.
 
 #### `extendedHookEvents` — `string[]` over a closed event vocabulary
 

docs/how-to/connect-gsd-mcp-server.md

@@ -1,7 +1,8 @@
 # How to connect a host to the GSD companion MCP server
 
 This guide shows you how to make a MCP-capable host (Claude Code, Codex,
-OpenCode, VS Code, Antigravity CLI, Cursor, Cline, Hermes) drive GSD — run GSD
+OpenCode, VS Code, Antigravity CLI, Cursor, Cline, Hermes, Augment Code) drive
+GSD — run GSD
 commands and read/write `.planning/` state — through the companion MCP server,
 with no bespoke plugin.
 
@@ -28,8 +29,18 @@ host.
 
 - **Claude Code / Codex / Cursor / Cline / Hermes** — under the host's
   `mcpServers` object (project or user config).
+- **Augment Code** — under the `mcpServers` block of its own
+  `settings.json` (not a standalone MCP config file, unlike Antigravity)
+  — global at `~/.augment/settings.json`, project-local at
+  `.augment/settings.json`. GSD's installer configures this entry
+  automatically (`--augment` installs).
 - **VS Code** — in the workspace MCP servers list.
-- **Antigravity CLI** — under its `mcpServers` block.
+- **Antigravity** — under the `mcpServers` block of its standalone
+  `mcp_config.json` profile (not embedded in `settings.json`) — global at
+  `~/.gemini/antigravity/mcp_config.json` (or the sibling
+  `antigravity-ide`/`antigravity-cli` dir GSD resolved into), project-local at
+  `.agents/mcp_config.json`. GSD's installer configures this entry
+  automatically (`--antigravity` installs).
 - **OpenCode** — under the `mcp` key (**not** `mcpServers`), in
   `~/.config/opencode/opencode.jsonc` (global) or `./opencode.json`
   (project). The entry shape also differs — see below.

docs/how-to/install-on-your-runtime.md

@@ -353,6 +353,22 @@ npx @opengsd/gsd-core@latest --codebuddy --global
 
 GSD installs four surfaces. Slash command definitions land in `~/.codebuddy/commands/gsd-*.md` and appear as `/gsd-help`, `/gsd-phase`, `/gsd-ship`, etc. in the `/` menu. Subagents land in `~/.codebuddy/agents/gsd-*.md`. Skills land in `~/.codebuddy/skills/gsd-*/SKILL.md` — emitted with `user-invocable: false` so they stay out of the `/` menu (the commands surface is the sole `/` entry point) and remain available for model invocation. CodeBuddy hooks are written to `settings.json`. No `mcp.json` is written: GSD ships no MCP server.
 
+**Hook coverage**
+
+GSD registers the following events automatically on install (Claude hook event dialect):
+
+| Event | Hook | Purpose |
+|---|---|---|
+| `SessionStart` | `gsd-check-update.js`, `gsd-session-state.sh` | Update check, session orientation |
+| `PreToolUse` | `gsd-prompt-guard.js`, `gsd-read-guard.js`, `gsd-workflow-guard.js`, `gsd-worktree-path-guard.js`, `gsd-validate-commit.sh` | Prompt guard, read-before-edit, workflow + worktree safety, commit validation |
+| `PostToolUse` | `gsd-context-monitor.js`, `gsd-read-injection-scanner.js`, `gsd-phase-boundary.sh`, `gsd-graphify-update.sh` | Context monitoring, read-time scan, phase boundary detection |
+| `SubagentStop` | `gsd-context-monitor.js` | Context headroom tracking after subagent completion |
+| `SubagentStart` | `gsd-context-monitor.js` | Context headroom tracking at subagent start |
+| `Stop` | `gsd-context-monitor.js` | Context headroom tracking before model stop |
+| `PreCompact` | `gsd-context-monitor.js` | Context awareness before conversation compaction |
+
+CodeBuddy's own [background sub-agent dispatch](https://www.codebuddy.ai/docs/cli/sub-agents) (`run_in_background: true`) is a caller-side invocation parameter, not something GSD's installed agent files control — there is no frontmatter field to set on GSD's agent artifacts to request it.
+
 ---
 
 ### Qwen Code
@@ -397,7 +413,7 @@ Qwen Code supports 15 hook events. GSD registers the following events automatica
 npx @opengsd/gsd-core@latest --augment --global
 ```
 
-Skills land in `~/.augment/skills/` and slash command definitions land in `~/.augment/commands/`. GSD installs skills, agents, and commands (`/gsd-phase`, `/gsd-ship`, etc.). No hook or statusline ownership.
+Skills land in `~/.augment/skills/` and slash command definitions land in `~/.augment/commands/`. GSD installs skills, agents, and commands (`/gsd-phase`, `/gsd-ship`, etc.). GSD's managed lifecycle hooks are registered into Augment's own `settings.json` `hooks` block (Claude hook event dialect, covering session-start, tool-use, and phase-boundary events) — no statusline ownership. #2097 also registers the GSD companion MCP server under `settings.json`'s `mcpServers.gsd` (see [Connect a host to the GSD MCP server](connect-gsd-mcp-server.md)).
 
 ---
 

docs/reference/capability-manifest.md

@@ -152,8 +152,8 @@ Runtime capabilities describe how GSD projects its artefacts onto one host CLI.
 | Support tier | `runtime.supportTier` | Integer: `1` (fully tested first-party) \| `2` (shipped, lower coverage). |
 | Install surface | `runtime.installSurface` | Closed enum: `settings-json` \| `codex-toml` \| `copilot-instructions` \| `cline-rules` \| `cursor-hooks-json` \| `profile-marker-only`. |
 | Shared settings | `runtime.writesSharedSettings` | boolean. Whether the runtime writes a shared `settings.json`. |
-| Permission writer | `runtime.permissionWriter` | `null` \| `"opencode"` \| `"kilo"`. The finish-time permissions-sidecar writer. |
-| Extended hook events | `runtime.extendedHookEvents` | string[] over a closed vocabulary: `SubagentStop`, `Stop`, `PreCompact`, `FileChanged`, `BeforeAgent`, `AfterAgent`, `BeforeModel`. |
+| Permission writer | `runtime.permissionWriter` | `null` \| `"opencode"` \| `"kilo"` \| `"antigravity"`. The finish-time permissions-sidecar writer. |
+| Extended hook events | `runtime.extendedHookEvents` | string[] over a closed vocabulary: `SubagentStop`, `Stop`, `PreCompact`, `FileChanged`, `BeforeAgent`, `AfterAgent`, `BeforeModel`, `SubagentStart`. |
 
 For a minimal `role: "runtime"` example, see [ADR-1016 §Decision 8](../adr/1016-runtime-capability-descriptor.md).
 

docs/reference/host-integration-capability-matrix.md

@@ -281,7 +281,7 @@ Documentation gaps:
 | dispatch.nested | undocumented | no authoritative doc — searched: https://antigravity.google/docs/agents | — |
 | dispatch.maxDepth | undocumented | no authoritative doc — searched: https://antigravity.google/docs/agents | — |
 | dispatch.background | true | https://developers.googleblog.com/an-important-update-transitioning-gemini-cli-to-antigravity-cli/ | "Antigravity CLI orchestrates multiple agents for complex tasks in the background" |
-| dispatch.subagentToolkit | undocumented | no authoritative doc — searched: https://www.explainx.ai/blog/antigravity-cli-features-sandbox-plugins-subagents-2026 | — |
+| dispatch.subagentToolkit | full | https://antigravity.google/docs/cli/features | "Capabilities: Subagents have full access to tools such as code search, file editing, terminal commands, and web searches to complete their assigned tasks." (#2096 EoS migration — the page is JS-rendered/blank on a static fetch; confirmed via headless-browser render) |
 | dispatch.backgroundDispatch | undocumented | no authoritative doc — Multiple sources consulted: antigravity.google/docs/cli-subagents (returned blank/JS-rendered), antigravity.google/docs/agent (blank), github.com/google-antigravity/antigravity-cli README, Context7 /google-antigravity/antigravity-cli | All documentation consulted describes a two-level orchestrator→subagent architecture. Background subagents run asynchronously while the main agent continues accepting prompts. The DataCamp tutorial st |
 
 Sources consulted:
@@ -292,12 +292,14 @@ Sources consulted:
 - https://www.aibuilderclub.com/blog/antigravity-cli-guide
 - https://antigravity.google/docs/agents
 - https://antigravity.google/docs/hooks
+- https://antigravity.google/docs/cli/features (#2096 — subagentToolkit)
 
 Documentation gaps:
 - dispatch.namedDispatch — docs describe dynamic plain-English goal dispatch where agent names subagents at runtime; no pre-registered named sub-agent API documented.
 - dispatch.nested — no documentation found on whether subagents can themselves spawn further subagents.
 - dispatch.maxDepth — no documented depth limit or explicit unbounded statement found.
-- dispatch.subagentToolkit — docs describe a permissions approval model but do not explicitly state 'full' vs 'read-only' toolkit scope for subagents.
+
+**EoS migration status (#2096):** Migrated onto the declarative adapter. All `runtime === 'antigravity'` / `isAntigravity` / `canonical === 'antigravity'` branches folded into descriptor-driven `runtime.hostBehaviors` + `runtime.hostIntegration`: `getConfigDirFromHome` (`bin/install.js`) now branches on `configHome.kind === 'dot-home-nested'` instead of a hardcoded runtime literal; `projectLocalHookPrefix` (`src/shell-command-projection.cts`) reads `hostBehaviors.hookPathStyle` (`'raw'` → bare `dirName`, no `$CLAUDE_PROJECT_DIR` anchor); `applyAgentPathRewrites` (`src/runtime-artifact-conversion.cts`) reads `hostBehaviors.noPathRewrite` to skip the `~/.claude/` → pathPrefix rewrites; and `getProjectInstructionFile` (`src/runtime-name-policy.cts`) reads `hostBehaviors.projectInstructionFile` (`"GEMINI.md"` — Antigravity CLI's `contextFileName`, successor to the sunset Gemini CLI per #1928) instead of a hardcoded `canonical === 'antigravity'` check. The dead `isAntigravity` branches these functions previously carried are removed. `dispatch.subagentToolkit` flipped `undocumented` → `full` per the citation above (antigravity.google/docs/cli/features); `dispatch.namedDispatch`/`nested`/`maxDepth`/`backgroundDispatch` stay `undocumented` — no authoritative source states named/nested/depth-bounded dispatch or a `run_in_background`-style call-time param, so `negotiateHostCapabilities` degrades all four closed to their most-restrictive value (false/0), and `shouldFlattenDispatch` still forces antigravity's dispatch to flatten (inline) despite `dispatch.background: true`, because `backgroundDispatch` itself never reaches `true`. Two upgrades land: **UPGRADE 1 — permission-writer** (`configureAntigravityPermissions`, `runtime.permissionWriter: "antigravity"`) writes Antigravity's native `{"permissions":{"allow":[...]}}` schema (antigravity.google/docs/cli/permissions) into the same `settings.json` GSD's own hook registration writes, granting GSD's own `read_file`/`command` rules non-destructively. **UPGRADE 2 — MCP companion config** (`configureAntigravityMcpConfig`) writes a standalone `mcp_config.json` (antigravity.google/docs/cli/gcli-migration) registering the `gsd` MCP server, non-destructively preserving any other `mcpServers` entries. Both upgrades are covered by `tests/antigravity-upgrades.test.cjs`; the axis/negotiation/source-grep coverage above is in `tests/declarative-reference-antigravity.test.cjs`.
 
 ---
 
@@ -332,6 +334,35 @@ Documentation gaps:
 - dispatch.nested
 - dispatch.maxDepth
 
+**EoS migration status (#2097):** Folded onto descriptor-driven dispatch.
+Augment already installed through the declarative adapter (nested-skill
+artifact layout, `settings-json` hook surface, Claude hook event dialect), but
+carried two remaining runtime-literal branches in
+`src/runtime-artifact-conversion.cts`: the 4 `~/.augment`/`$HOME/.augment`
+dot-dir rewrites in `_applyRuntimeRewrites`'s `case 'augment':` block are now
+built from `getDirName('augment')` (dirName-derived, byte-identical) instead
+of a hardcoded `.augment` literal, and the
+`applyRuntimeContentRewritesForCommandsInPlace` command-body conversion
+dispatch now reads `runtime.hostBehaviors.commandBodyConverter`
+(`"convertClaudeToAugmentMarkdown"`) instead of a hardcoded
+`runtime === 'augment'` branch. Two dead-code sites were also removed from
+`bin/install.js`: the orphaned `claudeToAugmentTools` map (superseded by the
+single-sourced converters per ADR-1508 / #1675) and the unreachable
+`else if (isAugment) { content = convertClaudeAgentToAugmentAgent(content); }`
+inline agent-conversion branch (augment has been on the descriptor-agents path
+since `_DESCRIPTOR_AGENTS_RUNTIMES` was introduced, making that `if`/`else if`
+arm dead). **UPGRADE 3 — MCP companion config**
+(`mergeGsdMcpServerIntoSettings`) registers the `gsd` MCP server directly
+inside the same `settings.json` `mcpServers` block GSD's own hook
+registration already writes (Augment hosts MCP in `settings.json`, unlike
+Antigravity's standalone `mcp_config.json`) — non-destructively preserving
+any other user-configured `mcpServers` entries; uninstall removes only the
+GSD-owned `gsd` entry. `settings.json` is golden-excluded
+(`HOOK_CONFIG_FILES`), so this upgrade produces no golden fixture change.
+Source-grep guard + fail-closed negotiation coverage is in
+`tests/declarative-reference-augment.test.cjs`; the dispatch/hook-bus/MCP
+upgrade coverage is in `tests/augment-upgrades.test.cjs`.
+
 ---
 
 ## qwen
@@ -396,6 +427,8 @@ Sources consulted:
 - https://www.codebuddy.ai/docs/cli/settings
 - /websites/codebuddy_cn (Context7)
 
+**EoS migration status (#2098):** Migrated onto the declarative adapter (dogfooded in `tests/declarative-reference-codebuddy.test.cjs`). The two remaining `isCodebuddy` branches in `bin/install.js` — a duplicate `commands/` slash-command output report, and a dead legacy agent-converter dispatch arm (unreachable since codebuddy is in `_DESCRIPTOR_AGENTS_RUNTIMES`) — were folded onto the already-generic `runtime.hostBehaviors.reportCommandsDir` (shared with Cursor) and removed outright; `isCodebuddy` no longer appears as a live read anywhere in `bin/install.js`, `src/runtime-artifact-conversion.cts`, `src/shell-command-projection.cts`, or `src/runtime-name-policy.cts`. Two upgrades land: (1) **extended hook events** — codebuddy's `extendedHookEvents` was previously `[]` (none wired); this PR wires all four — `SubagentStop`/`Stop`/`PreCompact`/`SubagentStart` — into `extendedHookEvents` (mirrors qwen/kimi), so an install now registers all four as hooks in `settings.json` alongside the pre-existing base session/tool events (`SessionStart`/`PreToolUse`/`PostToolUse`); cite https://www.codebuddy.ai/docs/cli/hooks. (2) **`dispatch.background`** — the descriptor already declared `true`, exceeding the `declarative-cli` profile baseline of `false`; the negotiation contract (`negotiateHostCapabilities`) now surfaces that value with no downgrade warning, documenting the legitimate deviation. Note: the CodeBuddy CLI has no background-dispatch frontmatter field on sub-agents (`agentMode`/`enabledAutoRun` are IDE-only per https://www.codebuddy.ai/docs/cli/sub-agents) — background dispatch remains a caller-side invocation parameter (`run_in_background: true`), not a field GSD's agent artifacts emit.
+
 ---
 
 ## copilot

gsd-core/bin/lib/capability-registry.cjs

@@ -165,7 +165,7 @@ const capabilities = {
       "supportTier": 1,
       "installSurface": "settings-json",
       "writesSharedSettings": true,
-      "permissionWriter": null,
+      "permissionWriter": "antigravity",
       "extendedHookEvents": [],
       "hostIntegration": {
         "embeddingMode": "declarative",
@@ -175,7 +175,7 @@ const capabilities = {
           "nested": "undocumented",
           "maxDepth": "undocumented",
           "background": true,
-          "subagentToolkit": "undocumented",
+          "subagentToolkit": "full",
           "backgroundDispatch": "undocumented"
         },
         "modelMode": "passive",
@@ -185,7 +185,11 @@ const capabilities = {
         "runtime": "go"
       },
       "hostBehaviors": {
-        "reviewerCli": true
+        "reviewerCli": true,
+        "projectInstructionFile": "GEMINI.md",
+        "noPathRewrite": true,
+        "hookPathStyle": "raw",
+        "globalDirResolver": "antigravity"
       }
     }
   },
@@ -356,6 +360,10 @@ const capabilities = {
       "writesSharedSettings": true,
       "permissionWriter": null,
       "extendedHookEvents": [],
+      "hostBehaviors": {
+        "commandBodyConverter": "convertClaudeToAugmentMarkdown",
+        "mcpCompanion": "settings-json"
+      },
       "hostIntegration": {
         "embeddingMode": "declarative",
         "commandSurface": "slash-file",
@@ -780,7 +788,12 @@ const capabilities = {
       "installSurface": "settings-json",
       "writesSharedSettings": true,
       "permissionWriter": null,
-      "extendedHookEvents": [],
+      "extendedHookEvents": [
+        "SubagentStop",
+        "Stop",
+        "PreCompact",
+        "SubagentStart"
+      ],
       "hostIntegration": {
         "embeddingMode": "declarative",
         "commandSurface": "slash-file",
@@ -797,6 +810,9 @@ const capabilities = {
         "stateIO": "filesystem",
         "transport": "mcp",
         "runtime": "node"
+      },
+      "hostBehaviors": {
+        "reportCommandsDir": true
       }
     }
   },
@@ -3837,7 +3853,7 @@ const runtimes = {
       "supportTier": 1,
       "installSurface": "settings-json",
       "writesSharedSettings": true,
-      "permissionWriter": null,
+      "permissionWriter": "antigravity",
       "extendedHookEvents": [],
       "hostIntegration": {
         "embeddingMode": "declarative",
@@ -3847,7 +3863,7 @@ const runtimes = {
           "nested": "undocumented",
           "maxDepth": "undocumented",
           "background": true,
-          "subagentToolkit": "undocumented",
+          "subagentToolkit": "full",
           "backgroundDispatch": "undocumented"
         },
         "modelMode": "passive",
@@ -3857,7 +3873,11 @@ const runtimes = {
         "runtime": "go"
       },
       "hostBehaviors": {
-        "reviewerCli": true
+        "reviewerCli": true,
+        "projectInstructionFile": "GEMINI.md",
+        "noPathRewrite": true,
+        "hookPathStyle": "raw",
+        "globalDirResolver": "antigravity"
       }
     }
   },
@@ -3945,6 +3965,10 @@ const runtimes = {
       "writesSharedSettings": true,
       "permissionWriter": null,
       "extendedHookEvents": [],
+      "hostBehaviors": {
+        "commandBodyConverter": "convertClaudeToAugmentMarkdown",
+        "mcpCompanion": "settings-json"
+      },
       "hostIntegration": {
         "embeddingMode": "declarative",
         "commandSurface": "slash-file",
@@ -4221,7 +4245,12 @@ const runtimes = {
       "installSurface": "settings-json",
       "writesSharedSettings": true,
       "permissionWriter": null,
-      "extendedHookEvents": [],
+      "extendedHookEvents": [
+        "SubagentStop",
+        "Stop",
+        "PreCompact",
+        "SubagentStart"
+      ],
       "hostIntegration": {
         "embeddingMode": "declarative",
         "commandSurface": "slash-file",
@@ -4238,6 +4267,9 @@ const runtimes = {
         "stateIO": "filesystem",
         "transport": "mcp",
         "runtime": "node"
+      },
+      "hostBehaviors": {
+        "reportCommandsDir": true
       }
     }
   },

gsd-core/bin/lib/capability-validator.cjs

@@ -717,7 +717,8 @@ const VALID_ARTIFACT_KIND_NAMES = new Set(['commands', 'agents', 'skills', 'kimi
 const VALID_ARTIFACT_NESTINGS = new Set(['flat', 'nested']);
 const FEATURE_FIELDS_FORBIDDEN_ON_RUNTIME = ['skills', 'agents', 'steps', 'contributions', 'gates', 'hooks', 'activationKey'];
 const VALID_INSTALL_SURFACES = new Set(['settings-json', 'codex-toml', 'copilot-instructions', 'cline-rules', 'cursor-hooks-json', 'profile-marker-only']);
-const VALID_PERMISSION_WRITERS = new Set(['opencode', 'kilo']);
+// 'antigravity' added #2096 Phase B Upgrade 1 — settings.json permissions.allow writer.
+const VALID_PERMISSION_WRITERS = new Set(['opencode', 'kilo', 'antigravity']);
 // SubagentStart added #2092 Phase B Upgrade 2 (qwen-only today — see
 // capabilities/qwen/capability.json's extendedHookEvents).
 const VALID_EXTENDED_HOOK_EVENTS = new Set(['SubagentStop', 'Stop', 'PreCompact', 'FileChanged', 'BeforeAgent', 'AfterAgent', 'BeforeModel', 'SubagentStart']);

src/runtime-artifact-conversion.cts

@@ -1107,6 +1107,11 @@ function convertClaudeToAugmentMarkdown(content) {
   return converted;
 }
 
+// #2097 (ADR-1239): command-body converters selected by descriptor
+// (runtime.hostBehaviors.commandBodyConverter) instead of a runtime-name
+// branch. Degrade-closed: unknown/absent name → no conversion.
+const COMMAND_BODY_CONVERTERS = { convertClaudeToAugmentMarkdown };
+
 function getAugmentSkillAdapterHeader(skillName) {
   return `<augment_skill_adapter>
 ## A. Skill Invocation
@@ -2442,19 +2447,24 @@ function _applyRuntimeRewrites(content, runtime, pathPrefix, isGlobal = false, a
       break;
     }
 
-    case 'augment':
+    case 'augment': {
       content = content.replace(/~\/\.claude\//g, pathPrefix);
       content = content.replace(/\$HOME\/\.claude\//g, pathPrefix);
       content = content.replace(/\.\/\.claude\//g, `./${dirName}/`);
       content = content.replace(/~\/\.claude(?![\w-])/g, normalizedPathPrefix);
       content = content.replace(/\$HOME\/\.claude(?![\w-])/g, normalizedPathPrefix);
       content = content.replace(/\.\/\.claude(?![\w-])/g, `./${dirName}`);
-      content = content.replace(/~\/\.augment\//g, pathPrefix);
-      content = content.replace(/\$HOME\/\.augment\//g, pathPrefix);
-      content = content.replace(/~\/\.augment(?![\w-])/g, normalizedPathPrefix);
-      content = content.replace(/\$HOME\/\.augment(?![\w-])/g, normalizedPathPrefix);
+      // #2097: dot-dir self-references (~/.augment/…) → resolved prefix,
+      // dirName-derived (no runtime literal). getDirName('augment') resolves
+      // to '.augment', so this is byte-identical to the prior hardcoded regexes.
+      const _dd = escapeRegExp(dirName);
+      content = content.replace(new RegExp('~/' + _dd + '/', 'g'), pathPrefix);
+      content = content.replace(new RegExp('\\$HOME/' + _dd + '/', 'g'), pathPrefix);
+      content = content.replace(new RegExp('~/' + _dd + '(?![\\w-])', 'g'), normalizedPathPrefix);
+      content = content.replace(new RegExp('\\$HOME/' + _dd + '(?![\\w-])', 'g'), normalizedPathPrefix);
       content = processAttribution(content, attribution);
       break;
+    }
 
     case 'trae':
       content = content.replace(/~\/\.claude\//g, pathPrefix);
@@ -2631,8 +2641,11 @@ function applyRuntimeContentRewritesForCommandsInPlace(stagedDir, runtime, pathP
       if (!entry.isFile() || !entry.name.endsWith('.md')) continue;
       let content = fs.readFileSync(path.join(stagedDir, entry.name), 'utf8');
       content = _applyRuntimeRewrites(content, runtime, pathPrefix, isGlobal, attribution);
-      if (runtime === 'augment') {
-        content = convertClaudeToAugmentMarkdown(content);
+      // #2097 (ADR-1239): descriptor-driven — commandBodyConverter name comes
+      // from runtime.hostBehaviors instead of a hardcoded runtime-name branch.
+      const _cmdConv = _hostBehaviors(runtime).commandBodyConverter;
+      if (_cmdConv && COMMAND_BODY_CONVERTERS[_cmdConv]) {
+        content = COMMAND_BODY_CONVERTERS[_cmdConv](content);
       }
       fs.writeFileSync(path.join(tempDir, entry.name), content);
     }
@@ -2743,9 +2756,11 @@ function normalizeAgentBodyForRuntime(content: string, runtime: string, cmdNames
  *   ~/\.claude\b → normalizedPathPrefix
  *   $HOME/\.claude\b → normalizedPathPrefix
  *
- * Skipped for copilot and antigravity (which do NOT do path rewrites in the
- * inline loop). NO stamp (_stampNonClaudeRuntimeDefaults) — agents are NOT
- * stamped in the inline loop.
+ * Skipped for copilot (hardcoded — #2099 will fold it) and for any runtime
+ * that declares `hostBehaviors.noPathRewrite` (descriptor-driven, ADR-1239 /
+ * #2096 — folds the prior hardcoded `runtime === 'antigravity'` literal;
+ * Antigravity does NOT do path rewrites in the inline loop). NO stamp
+ * (_stampNonClaudeRuntimeDefaults) — agents are NOT stamped in the inline loop.
  *
  * ADR-1235 §1: pre-converter cross-cutting for descriptor-driven agent pipeline.
  * Exported as `applyAgentPathRewrites` for testing and for injection into
@@ -2754,10 +2769,10 @@ function normalizeAgentBodyForRuntime(content: string, runtime: string, cmdNames
  * @param content     raw agent file content
  * @param runtime     canonical runtime ID
  * @param pathPrefix  trailing-slash path prefix (e.g. '$HOME/.cursor/')
- * @returns content with path-prefix rewrites applied (or unchanged for copilot/antigravity)
+ * @returns content with path-prefix rewrites applied (or unchanged for copilot / noPathRewrite runtimes)
  */
 function applyAgentPathRewrites(content: string, runtime: string, pathPrefix: string): string {
-  if (runtime === 'copilot' || runtime === 'antigravity') return content;
+  if (runtime === 'copilot' || _hostBehaviors(runtime).noPathRewrite === true) return content;
   const normalizedPathPrefix = pathPrefix.replace(/\/$/, '');
   content = content.replace(/~\/\.claude\//g, pathPrefix);
   content = content.replace(/\$HOME\/\.claude\//g, pathPrefix);

src/runtime-config-adapter-registry.cts

@@ -22,9 +22,12 @@
  *     false for codex / copilot / kilo / cursor / windsurf / trae / cline / kimi (legacy exclusion list).
  *     true for all other runtimes.
  * - `finishPermissionWriter` names the finishInstall-phase dedicated config writer:
- *     'opencode' → writes BOTH shared settings AND its own permissions file.
- *     'kilo'     → writes only its own permissions file.
- *     null       → no dedicated permission writer.
+ *     'opencode'    → writes BOTH shared settings AND its own permissions file.
+ *     'kilo'        → writes only its own permissions file.
+ *     'antigravity' → writes BOTH shared settings.json permissions.allow AND a
+ *                      standalone mcp_config.json MCP companion profile (#2096
+ *                      Phase B Upgrades 1+2).
+ *     null          → no dedicated permission writer.
  */
 
 // eslint-disable-next-line @typescript-eslint/no-require-imports
@@ -45,7 +48,7 @@ type ConfigInstallSurface =
   | 'cursor-hooks-json'
   | 'profile-marker-only';
 
-type FinishPermissionWriter = 'opencode' | 'kilo' | null;
+type FinishPermissionWriter = 'opencode' | 'kilo' | 'antigravity' | null;
 
 type HooksSurface =
   | 'settings-json'

src/runtime-name-policy.cts

@@ -120,13 +120,26 @@ export function resolveRuntimeNameFromCandidates(...candidates: unknown[]): stri
  * Aliases are normalized via `canonicalizeRuntimeName` first, so inputs like
  * `codex-cli` resolve to `codex` → `AGENTS.md`. Replaces the prior codex-only
  * override in profile-output.cjs (#3163) which left AGENTS-native runtimes
- * (opencode/kilo/kimi) incorrectly emitting `.claude/CLAUDE.md`. Pure: no I/O.
+ * (opencode/kilo/kimi) incorrectly emitting `.claude/CLAUDE.md`. Pure: no I/O
+ * (the lazy `require` below reads a static generated module, not the disk).
+ *
+ * Descriptor-driven (ADR-1239 / #2096): antigravity's `GEMINI.md` is folded
+ * from a hardcoded `canonical === 'antigravity'` literal into a read of
+ * `runtime.hostBehaviors.projectInstructionFile`. claude/copilot stay
+ * hardcoded (out of scope here) mirroring `getDirName` below, which already
+ * lazy-`require`s `capability-registry.cjs` inside the function body to
+ * avoid a circular dependency at module load.
  */
 export function getProjectInstructionFile(runtime: unknown): string {
   const canonical = canonicalizeRuntimeName(runtime);
   if (canonical === 'claude') return '.claude/CLAUDE.md';
   if (canonical === 'copilot') return '.github/copilot-instructions.md';
-  if (canonical === 'antigravity') return 'GEMINI.md';
+  // eslint-disable-next-line @typescript-eslint/no-require-imports
+  const { runtimes } = require('./capability-registry.cjs') as {
+    runtimes: Record<string, { runtime?: { hostBehaviors?: { projectInstructionFile?: string } } } | undefined>;
+  };
+  const declared = canonical ? runtimes[canonical]?.runtime?.hostBehaviors?.projectInstructionFile : undefined;
+  if (typeof declared === 'string' && declared.length > 0) return declared;
   // codex, opencode, kilo, kimi, AND unknown/future runtimes all default to
   // root AGENTS.md (the safe cross-agent instruction file).
   return 'AGENTS.md';

src/shell-command-projection.cts

@@ -98,9 +98,17 @@ export function formatManagedHookScriptToken(scriptPath: string, opts: { platfor
   return JSON.stringify(scriptPath.replace(/\\/g, '/'));
 }
 
-export function projectLocalHookPrefix({ runtime = 'claude', dirName }: { runtime?: string; dirName?: string | null }): string | undefined | null {
+export function projectLocalHookPrefix({ runtime: _runtime = 'claude', dirName, hookPathStyle }: { runtime?: string; dirName?: string | null; hookPathStyle?: string | null }): string | undefined | null {
   if (!dirName) return dirName;
-  return (runtime === 'antigravity')
+  // Descriptor-driven (ADR-1239 / #2096): folded from a hardcoded
+  // `runtime === 'antigravity'` literal into the runtime's declared
+  // `hostBehaviors.hookPathStyle`. Runtimes that always run project hooks
+  // with the project dir as cwd (Antigravity today) declare 'raw' and get
+  // the bare dirName; every other runtime keeps the $CLAUDE_PROJECT_DIR-
+  // anchored prefix. `runtime` itself is now unused here but stays in the
+  // signature for call-site/back-compat parity (kept `_`-prefixed to
+  // satisfy no-unused-vars).
+  return (hookPathStyle === 'raw')
     ? dirName
     : `"$CLAUDE_PROJECT_DIR"/${dirName}`;
 }

tests/antigravity-upgrades.test.cjs

@@ -0,0 +1,283 @@
+'use strict';
+
+/**
+ * antigravity capability UPGRADES — ADR-1239 Phase B / #2096 (EoS/antigravity).
+ *
+ * Drives the user-reachable surface (spawned `bin/install.js` via
+ * `runMinimalInstall`) plus targeted unit coverage to prove the two real
+ * upgrades Antigravity contributes as part of the imperative-adapter
+ * migration:
+ *
+ *   UPGRADE 1 — permission-writer: `configureAntigravityPermissions` writes
+ *   Antigravity's native `{"permissions":{"allow":[...]}}` schema
+ *   (antigravity.google/docs/cli/permissions) into the SAME settings.json
+ *   GSD's own hook registration writes, non-destructively appending GSD's own
+ *   read_file/command allow rules while preserving any existing user
+ *   permissions (allow/deny/ask). Uninstall removes only the GSD-owned rules.
+ *
+ *   UPGRADE 2 — MCP companion config: `configureAntigravityMcpConfig` writes
+ *   a standalone `mcp_config.json` (antigravity.google/docs/cli/gcli-migration)
+ *   registering the `gsd` MCP server (`bin/gsd-mcp-server.js`, the SAME
+ *   companion OpenCode/Kilo document/wire), non-destructively preserving any
+ *   other user-configured `mcpServers` entries. Uninstall removes only the
+ *   `gsd` entry.
+ *
+ * Both writers are NOT GSD_TEST_MODE-gated (mirrors Kilo's dispatch, not
+ * OpenCode's) — runMinimalInstall strips GSD_TEST_MODE from the spawned
+ * installer's env, so both fire during a "minimal" install too.
+ */
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const { spawnSync } = require('node:child_process');
+
+const { runMinimalInstall, installerEnv, INSTALL_SCRIPT } = require('./helpers/install-shared.cjs');
+const { cleanup } = require('./helpers.cjs');
+const {
+  toTildePosixPath,
+  buildAntigravityAllowRules,
+  configureAntigravityPermissions,
+  configureAntigravityMcpConfig,
+} = require('../bin/install.js');
+const { PROTOCOL_VERSION } = require('../gsd-core/bin/lib/mcp-server.cjs');
+const { PACKAGE_NAME } = require('../gsd-core/bin/lib/package-identity.cjs');
+
+const MCP_SERVER_BIN = path.join(__dirname, '..', 'bin', 'gsd-mcp-server.js');
+
+const ANTIGRAVITY_CAP = JSON.parse(
+  fs.readFileSync(path.join(__dirname, '..', 'capabilities', 'antigravity', 'capability.json'), 'utf8'),
+);
+
+// ---------------------------------------------------------------------------
+// Descriptor boundary — permissionWriter wiring
+// ---------------------------------------------------------------------------
+
+test('capabilities/antigravity/capability.json declares runtime.permissionWriter: "antigravity"', () => {
+  assert.equal(ANTIGRAVITY_CAP.runtime.permissionWriter, 'antigravity');
+});
+
+// ---------------------------------------------------------------------------
+// UPGRADE 1: permission-writer unit coverage (toTildePosixPath / rule builder)
+// ---------------------------------------------------------------------------
+
+test('toTildePosixPath collapses a homedir-rooted path to "~/..." form', () => {
+  const home = require('node:os').homedir();
+  assert.equal(toTildePosixPath(path.join(home, '.gemini', 'antigravity')), '~/.gemini/antigravity');
+});
+
+test('toTildePosixPath leaves a non-homedir path as an absolute posix path', () => {
+  assert.equal(toTildePosixPath('/var/tmp/some-config-dir'), '/var/tmp/some-config-dir');
+});
+
+test('buildAntigravityAllowRules emits the 4 documented "action(target)" rule strings', () => {
+  const rules = buildAntigravityAllowRules('/tmp/ag-config');
+  assert.deepEqual(rules, [
+    'read_file(/tmp/ag-config/gsd-core/*)',
+    'read_file(/tmp/ag-config/agents/gsd-*)',
+    'read_file(/tmp/ag-config/skills/gsd-*)',
+    'command(node /tmp/ag-config/hooks/*)',
+  ]);
+});
+
+// ---------------------------------------------------------------------------
+// UPGRADE 1: live install — settings.json permissions.allow (both scopes)
+// ---------------------------------------------------------------------------
+
+for (const scope of ['global', 'local']) {
+  test(`antigravity --${scope}: settings.json permissions.allow contains GSD's rules (UPGRADE 1)`, (t) => {
+    const { configDir, root } = runMinimalInstall({ runtime: 'antigravity', scope });
+    t.after(() => cleanup(root));
+
+    const settingsPath = path.join(configDir, 'settings.json');
+    assert.ok(fs.existsSync(settingsPath), `${settingsPath} must exist`);
+
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+    assert.ok(settings.permissions && Array.isArray(settings.permissions.allow), 'permissions.allow must be an array');
+
+    // Asserting on the exact rule strings here would require reproducing
+    // toTildePosixPath's os.homedir()-relative substitution from OUTSIDE the
+    // spawned installer subprocess: runMinimalInstall overrides that
+    // subprocess's HOME to `root`, so for --global (configDir === root ===
+    // that subprocess's HOME) every rule collapses to the bare `~/...` form,
+    // while THIS test process's own (unrelated, real) os.homedir() would
+    // reconstruct full absolute paths instead — a guaranteed mismatch that
+    // has nothing to do with correctness. Assert on the documented rule
+    // SHAPE (action + path suffix) instead, which holds regardless of
+    // whether the prefix collapsed to `~` or stayed a full absolute path.
+    const expectedShapes = [
+      { action: 'read_file(', suffix: '/gsd-core/*)' },
+      { action: 'read_file(', suffix: '/agents/gsd-*)' },
+      { action: 'read_file(', suffix: '/skills/gsd-*)' },
+      { action: 'command(node ', suffix: '/hooks/*)' },
+    ];
+    for (const { action, suffix } of expectedShapes) {
+      const found = settings.permissions.allow.some((rule) => rule.startsWith(action) && rule.endsWith(suffix));
+      assert.ok(found, `permissions.allow must include a rule shaped like "${action}...${suffix}" — got ${JSON.stringify(settings.permissions.allow)}`);
+    }
+    // Priority-scoping (deny/ask) is a user-owned decision — GSD never writes it.
+    assert.equal(settings.permissions.deny, undefined, 'GSD must never write permissions.deny');
+    assert.equal(settings.permissions.ask, undefined, 'GSD must never write permissions.ask');
+  });
+}
+
+test('configureAntigravityPermissions is idempotent — a second call adds no duplicate rules', (t) => {
+  const root = fs.mkdtempSync(path.join(require('node:os').tmpdir(), 'gsd-ag-perm-idem-'));
+  t.after(() => cleanup(root));
+
+  configureAntigravityPermissions(true, root);
+  configureAntigravityPermissions(true, root);
+  const settings = JSON.parse(fs.readFileSync(path.join(root, 'settings.json'), 'utf8'));
+  assert.equal(settings.permissions.allow.length, new Set(settings.permissions.allow).size, 'no duplicate allow entries');
+  assert.equal(settings.permissions.allow.length, buildAntigravityAllowRules(root).length);
+});
+
+test('configureAntigravityPermissions preserves a pre-existing user permissions block (allow/deny/ask)', (t) => {
+  const root = fs.mkdtempSync(path.join(require('node:os').tmpdir(), 'gsd-ag-perm-preserve-'));
+  t.after(() => cleanup(root));
+
+  fs.writeFileSync(path.join(root, 'settings.json'), JSON.stringify({
+    permissions: {
+      allow: ['command(git)'],
+      deny: ['command(rm -rf)'],
+      ask: ['command(*)'],
+    },
+    userCustomField: 'preserve-me',
+  }, null, 2));
+
+  configureAntigravityPermissions(true, root);
+
+  const settings = JSON.parse(fs.readFileSync(path.join(root, 'settings.json'), 'utf8'));
+  assert.ok(settings.permissions.allow.includes('command(git)'), 'pre-existing allow entry preserved');
+  assert.deepEqual(settings.permissions.deny, ['command(rm -rf)'], 'deny block untouched');
+  assert.deepEqual(settings.permissions.ask, ['command(*)'], 'ask block untouched');
+  assert.equal(settings.userCustomField, 'preserve-me', 'unrelated top-level user fields preserved');
+  for (const rule of buildAntigravityAllowRules(root)) {
+    assert.ok(settings.permissions.allow.includes(rule));
+  }
+});
+
+// ---------------------------------------------------------------------------
+// UPGRADE 2: MCP companion config — live install (both scopes)
+// ---------------------------------------------------------------------------
+
+for (const scope of ['global', 'local']) {
+  test(`antigravity --${scope}: mcp_config.json registers the gsd MCP companion (UPGRADE 2)`, (t) => {
+    const { configDir, root } = runMinimalInstall({ runtime: 'antigravity', scope });
+    t.after(() => cleanup(root));
+
+    const mcpConfigPath = path.join(configDir, 'mcp_config.json');
+    assert.ok(fs.existsSync(mcpConfigPath), `${mcpConfigPath} must exist`);
+
+    const mcpConfig = JSON.parse(fs.readFileSync(mcpConfigPath, 'utf8'));
+    assert.ok(mcpConfig.mcpServers && mcpConfig.mcpServers.gsd, 'mcpServers.gsd must be present');
+    assert.equal(mcpConfig.mcpServers.gsd.command, 'npx');
+    assert.deepEqual(mcpConfig.mcpServers.gsd.args, ['-y', '-p', PACKAGE_NAME, 'gsd-mcp-server']);
+  });
+}
+
+test('configureAntigravityMcpConfig is idempotent — a second call does not clobber an existing gsd entry', (t) => {
+  const root = fs.mkdtempSync(path.join(require('node:os').tmpdir(), 'gsd-ag-mcp-idem-'));
+  t.after(() => cleanup(root));
+
+  configureAntigravityMcpConfig(true, root);
+  // Simulate a user hand-edit of the gsd entry after install.
+  const configPath = path.join(root, 'mcp_config.json');
+  const config = JSON.parse(fs.readFileSync(configPath, 'utf8'));
+  config.mcpServers.gsd.args.push('--custom-flag');
+  fs.writeFileSync(configPath, JSON.stringify(config, null, 2) + '\n');
+
+  configureAntigravityMcpConfig(true, root);
+
+  const after = JSON.parse(fs.readFileSync(configPath, 'utf8'));
+  assert.ok(after.mcpServers.gsd.args.includes('--custom-flag'), 'a user-owned gsd override is never clobbered (Hyrum\'s Law)');
+});
+
+test('configureAntigravityMcpConfig preserves a pre-existing unrelated mcpServers entry', (t) => {
+  const root = fs.mkdtempSync(path.join(require('node:os').tmpdir(), 'gsd-ag-mcp-preserve-'));
+  t.after(() => cleanup(root));
+
+  fs.writeFileSync(path.join(root, 'mcp_config.json'), JSON.stringify({
+    mcpServers: {
+      'my-own-server': { command: 'my-tool', args: ['--flag'] },
+    },
+  }, null, 2));
+
+  configureAntigravityMcpConfig(true, root);
+
+  const config = JSON.parse(fs.readFileSync(path.join(root, 'mcp_config.json'), 'utf8'));
+  assert.deepEqual(config.mcpServers['my-own-server'], { command: 'my-tool', args: ['--flag'] });
+  assert.ok(config.mcpServers.gsd);
+});
+
+// AC-style proof: the companion mcp_config.json points at (bin/gsd-mcp-server.js)
+// is actually reachable, not just documented. Mirrors tests/gsd-mcp-server-bin.test.cjs
+// exactly (same shim, same line-delimited JSON-RPC over stdio).
+test('UPGRADE 2: gsd-mcp-server companion is reachable — spawn, initialize, tools/list over stdio', () => {
+  const stdin = [
+    JSON.stringify({ jsonrpc: '2.0', id: 1, method: 'initialize' }),
+    JSON.stringify({ jsonrpc: '2.0', id: 2, method: 'tools/list' }),
+  ].join('\n') + '\n';
+
+  const res = spawnSync(process.execPath, [MCP_SERVER_BIN], {
+    input: stdin,
+    encoding: 'utf-8',
+    timeout: 15000,
+    env: { ...process.env, GSD_TEST_MODE: '1' },
+  });
+
+  assert.strictEqual(res.status, 0, `gsd-mcp-server must exit cleanly on stdin EOF; stderr: ${res.stderr}`);
+  const lines = res.stdout.trim().split('\n').map((l) => JSON.parse(l));
+  assert.strictEqual(lines.length, 2, 'one response per request');
+  assert.strictEqual(lines[0].result.protocolVersion, PROTOCOL_VERSION, 'initialize handshake succeeds');
+  const toolNames = lines[1].result.tools.map((t) => t.name).sort();
+  assert.deepStrictEqual(
+    toolNames,
+    ['gsd_invoke_command', 'gsd_read_state', 'gsd_write_state'],
+    'the companion the mcp_config.json entry connects to advertises the real GSD tool surface',
+  );
+});
+
+// ---------------------------------------------------------------------------
+// Uninstall — symmetric cleanup for both upgrades
+// ---------------------------------------------------------------------------
+
+test('antigravity --global uninstall removes only GSD-owned permissions.allow rules + mcpServers.gsd, preserving user data', (t) => {
+  const root = fs.mkdtempSync(path.join(require('node:os').tmpdir(), 'gsd-ag-uninstall-'));
+  t.after(() => cleanup(root));
+
+  const args = [INSTALL_SCRIPT, '--antigravity', '--global', '--config-dir', root];
+  const installResult = spawnSync(process.execPath, args, {
+    encoding: 'utf8',
+    env: installerEnv({ HOME: root, USERPROFILE: root }),
+  });
+  assert.strictEqual(installResult.status, 0, `install failed: ${installResult.stderr}`);
+
+  // Seed user-owned data alongside GSD's contributions, post-install.
+  const settingsPath = path.join(root, 'settings.json');
+  const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+  settings.permissions.allow.push('command(git)');
+  settings.permissions.deny = ['command(rm -rf)'];
+  fs.writeFileSync(settingsPath, JSON.stringify(settings, null, 2) + '\n');
+
+  const mcpConfigPath = path.join(root, 'mcp_config.json');
+  const mcpConfig = JSON.parse(fs.readFileSync(mcpConfigPath, 'utf8'));
+  mcpConfig.mcpServers['my-own-server'] = { command: 'my-tool', args: [] };
+  fs.writeFileSync(mcpConfigPath, JSON.stringify(mcpConfig, null, 2) + '\n');
+
+  const uninstallArgs = [INSTALL_SCRIPT, '--antigravity', '--global', '--config-dir', root, '--uninstall'];
+  const uninstallResult = spawnSync(process.execPath, uninstallArgs, {
+    encoding: 'utf8',
+    env: installerEnv({ HOME: root, USERPROFILE: root }),
+  });
+  assert.strictEqual(uninstallResult.status, 0, `uninstall failed: ${uninstallResult.stderr}`);
+
+  const settingsAfter = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+  assert.deepEqual(settingsAfter.permissions.allow, ['command(git)'], 'GSD allow rules removed, user rule preserved');
+  assert.deepEqual(settingsAfter.permissions.deny, ['command(rm -rf)'], 'user deny rule preserved');
+
+  const mcpConfigAfter = JSON.parse(fs.readFileSync(mcpConfigPath, 'utf8'));
+  assert.equal(mcpConfigAfter.mcpServers.gsd, undefined, 'gsd MCP entry removed');
+  assert.deepEqual(mcpConfigAfter.mcpServers['my-own-server'], { command: 'my-tool', args: [] }, 'user MCP server preserved');
+});

tests/augment-upgrades.test.cjs

@@ -0,0 +1,243 @@
+'use strict';
+
+/**
+ * Augment Code capability UPGRADES — ADR-1239 / #2097 (EoS/augment migration).
+ *
+ * Mirrors tests/antigravity-upgrades.test.cjs's structure. Augment already
+ * shipped as a declarative-CLI host prior to #2097 (nested-skill artifact
+ * layout, settings-json hook surface, Claude hook event dialect, dispatch
+ * namedDispatch/background/subagentToolkit:'full'), so UPGRADE 1 (dispatch)
+ * and UPGRADE 2 (hook-bus) below are REGRESSION locks on that pre-existing
+ * wiring, not new capabilities. UPGRADE 3 (MCP companion) IS new: #2097 adds
+ * `mergeGsdMcpServerIntoSettings`, registering the GSD companion MCP server
+ * inside Augment's own settings.json `mcpServers` block (Augment hosts MCP
+ * there, unlike Antigravity's standalone mcp_config.json) — non-destructively
+ * appending GSD's own entry while preserving any other user-configured
+ * `mcpServers` entries. Uninstall removes only the GSD-owned `gsd` entry.
+ */
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const os = require('node:os');
+const { spawnSync } = require('node:child_process');
+
+const { runMinimalInstall, installerEnv, INSTALL_SCRIPT } = require('./helpers/install-shared.cjs');
+const { cleanup } = require('./helpers.cjs');
+const {
+  mergeGsdMcpServerIntoSettings,
+} = require('../bin/install.js');
+const { negotiateHostCapabilities } = require('../gsd-core/bin/lib/host-integration.cjs');
+const { PACKAGE_NAME } = require('../gsd-core/bin/lib/package-identity.cjs');
+
+const AUGMENT_CAP = JSON.parse(
+  fs.readFileSync(path.join(__dirname, '..', 'capabilities', 'augment', 'capability.json'), 'utf8'),
+);
+
+// ---------------------------------------------------------------------------
+// UPGRADE 1: dispatch — descriptor + negotiation regression lock
+// ---------------------------------------------------------------------------
+
+test('capabilities/augment/capability.json declares dispatch.namedDispatch/background/subagentToolkit for full subagent support (UPGRADE 1)', () => {
+  const dispatch = AUGMENT_CAP.runtime.hostIntegration.dispatch;
+  assert.equal(dispatch.namedDispatch, true);
+  assert.equal(dispatch.background, true);
+  assert.equal(dispatch.subagentToolkit, 'full');
+});
+
+test('negotiateHostCapabilities does NOT flatten dispatch for augment — namedDispatch/background/subagentToolkit survive negotiation (UPGRADE 1)', () => {
+  const { effective } = negotiateHostCapabilities(AUGMENT_CAP.runtime.hostIntegration);
+  assert.equal(effective.dispatch.namedDispatch, true,
+    'documented namedDispatch:true must survive negotiation unflattened');
+  assert.equal(effective.dispatch.background, true,
+    'documented background:true must survive negotiation unflattened (not capped to false)');
+  assert.equal(effective.dispatch.subagentToolkit, 'full',
+    'documented subagentToolkit:full must survive negotiation unflattened');
+});
+
+// ---------------------------------------------------------------------------
+// UPGRADE 2: hook-bus — live install proves the settings.json hook surface
+// (SessionStart/PostToolUse/PreToolUse) is actually wired for augment.
+// ---------------------------------------------------------------------------
+
+for (const scope of ['global', 'local']) {
+  test(`augment --${scope}: settings.json contains GSD's managed hook entries (UPGRADE 2)`, (t) => {
+    const { configDir, root } = runMinimalInstall({ runtime: 'augment', scope });
+    t.after(() => cleanup(root));
+
+    const settingsPath = path.join(configDir, 'settings.json');
+    assert.ok(fs.existsSync(settingsPath), `${settingsPath} must exist`);
+
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+    assert.ok(settings.hooks && typeof settings.hooks === 'object', 'settings.hooks must be an object');
+
+    // Augment's hookEvents dialect is 'claude' (capabilities/augment/capability.json),
+    // so it gets the Claude-dialect event names (PostToolUse/PreToolUse), not
+    // antigravity's gemini-dialect (AfterTool/BeforeTool).
+    assert.ok(Array.isArray(settings.hooks.SessionStart) && settings.hooks.SessionStart.length > 0,
+      'settings.hooks.SessionStart must be registered');
+    assert.ok(Array.isArray(settings.hooks.PostToolUse) && settings.hooks.PostToolUse.length > 0,
+      'settings.hooks.PostToolUse must be registered');
+    assert.ok(Array.isArray(settings.hooks.PreToolUse) && settings.hooks.PreToolUse.length > 0,
+      'settings.hooks.PreToolUse must be registered');
+
+    const hasGsdCommand = (entries) => entries.some(
+      (entry) => entry && Array.isArray(entry.hooks) &&
+        entry.hooks.some((h) => h && typeof h.command === 'string' && h.command.includes('gsd-')),
+    );
+    assert.ok(hasGsdCommand(settings.hooks.SessionStart), 'SessionStart must reference a gsd- managed hook');
+    assert.ok(hasGsdCommand(settings.hooks.PostToolUse), 'PostToolUse must reference a gsd- managed hook');
+    assert.ok(hasGsdCommand(settings.hooks.PreToolUse), 'PreToolUse must reference a gsd- managed hook');
+  });
+}
+
+// ---------------------------------------------------------------------------
+// UPGRADE 3: MCP companion config — direct-unit idempotency + preservation
+// (mirrors antigravity's configureAntigravityMcpConfig unit tests exactly,
+// scoped to the in-memory settings object mergeGsdMcpServerIntoSettings mutates).
+// ---------------------------------------------------------------------------
+
+test('mergeGsdMcpServerIntoSettings adds mcpServers.gsd with command "npx" and args including gsd-mcp-server + PACKAGE_NAME', () => {
+  const settings = {};
+  mergeGsdMcpServerIntoSettings(settings);
+  assert.ok(settings.mcpServers && settings.mcpServers.gsd, 'mcpServers.gsd must be present');
+  assert.equal(settings.mcpServers.gsd.command, 'npx');
+  assert.deepEqual(settings.mcpServers.gsd.args, ['-y', '-p', PACKAGE_NAME, 'gsd-mcp-server']);
+});
+
+test('mergeGsdMcpServerIntoSettings is idempotent — a second call does not clobber an existing gsd entry', () => {
+  const settings = {};
+  mergeGsdMcpServerIntoSettings(settings);
+  // Simulate a user hand-edit of the gsd entry after install.
+  settings.mcpServers.gsd.args.push('--custom-flag');
+
+  mergeGsdMcpServerIntoSettings(settings);
+
+  assert.ok(settings.mcpServers.gsd.args.includes('--custom-flag'),
+    "a user-owned gsd override is never clobbered (Hyrum's Law)");
+  assert.equal(Object.keys(settings.mcpServers).length, 1, 'exactly one mcpServers entry (gsd)');
+});
+
+test('mergeGsdMcpServerIntoSettings preserves a pre-existing unrelated mcpServers entry', () => {
+  const settings = {
+    mcpServers: {
+      'my-own-server': { command: 'my-tool', args: ['--flag'] },
+    },
+  };
+  mergeGsdMcpServerIntoSettings(settings);
+
+  assert.deepEqual(settings.mcpServers['my-own-server'], { command: 'my-tool', args: ['--flag'] });
+  assert.ok(settings.mcpServers.gsd);
+  assert.equal(Object.keys(settings.mcpServers).length, 2, 'both entries present');
+});
+
+test('mergeGsdMcpServerIntoSettings recovers a corrupted (non-object) mcpServers field', () => {
+  const settingsArrayCase = { mcpServers: ['not', 'an', 'object'] };
+  mergeGsdMcpServerIntoSettings(settingsArrayCase);
+  assert.ok(settingsArrayCase.mcpServers.gsd, 'array mcpServers must be recovered to an object with gsd set');
+
+  const settingsStringCase = { mcpServers: 'corrupted-string' };
+  mergeGsdMcpServerIntoSettings(settingsStringCase);
+  assert.ok(settingsStringCase.mcpServers.gsd, 'non-object mcpServers must be recovered to an object with gsd set');
+});
+
+// ---------------------------------------------------------------------------
+// UPGRADE 3: MCP companion config — live install (both scopes) proves the
+// end-to-end wiring through finishInstall, not just the unit function.
+// ---------------------------------------------------------------------------
+
+for (const scope of ['global', 'local']) {
+  test(`augment --${scope}: settings.json registers the gsd MCP companion (UPGRADE 3)`, (t) => {
+    const { configDir, root } = runMinimalInstall({ runtime: 'augment', scope });
+    t.after(() => cleanup(root));
+
+    const settingsPath = path.join(configDir, 'settings.json');
+    assert.ok(fs.existsSync(settingsPath), `${settingsPath} must exist`);
+
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+    assert.ok(settings.mcpServers && settings.mcpServers.gsd, 'mcpServers.gsd must be present');
+    assert.equal(settings.mcpServers.gsd.command, 'npx');
+    assert.deepEqual(settings.mcpServers.gsd.args, ['-y', '-p', PACKAGE_NAME, 'gsd-mcp-server']);
+  });
+}
+
+test('augment --global: reinstalling does not duplicate or clobber the gsd MCP companion entry (live-install idempotency)', (t) => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-augment-mcp-idem-'));
+  t.after(() => cleanup(root));
+
+  const args = [INSTALL_SCRIPT, '--augment', '--global', '--config-dir', root];
+  const env = installerEnv({ HOME: root, USERPROFILE: root });
+
+  const first = spawnSync(process.execPath, args, { encoding: 'utf8', env });
+  assert.strictEqual(first.status, 0, `first install failed: ${first.stderr}`);
+
+  const settingsPath = path.join(root, 'settings.json');
+  const afterFirst = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+  assert.ok(afterFirst.mcpServers.gsd);
+  // Simulate a user hand-edit of the gsd entry between installs.
+  afterFirst.mcpServers.gsd.args.push('--custom-flag');
+  fs.writeFileSync(settingsPath, JSON.stringify(afterFirst, null, 2) + '\n');
+
+  const second = spawnSync(process.execPath, args, { encoding: 'utf8', env });
+  assert.strictEqual(second.status, 0, `second install failed: ${second.stderr}`);
+
+  const afterSecond = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+  assert.equal(Object.keys(afterSecond.mcpServers).length, 1, 'reinstall must not duplicate the gsd entry');
+  assert.ok(afterSecond.mcpServers.gsd.args.includes('--custom-flag'),
+    "a user-owned gsd override is never clobbered across reinstall (Hyrum's Law)");
+});
+
+test('augment --global: installing preserves a pre-existing unrelated mcpServers entry (live-install preservation)', (t) => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-augment-mcp-preserve-'));
+  fs.mkdirSync(root, { recursive: true });
+  t.after(() => cleanup(root));
+
+  // Pre-seed settings.json with a user's own MCP server BEFORE install runs.
+  fs.writeFileSync(path.join(root, 'settings.json'), JSON.stringify({
+    mcpServers: {
+      other: { command: 'my-tool', args: ['--flag'] },
+    },
+  }, null, 2));
+
+  const args = [INSTALL_SCRIPT, '--augment', '--global', '--config-dir', root];
+  const result = spawnSync(process.execPath, args, {
+    encoding: 'utf8',
+    env: installerEnv({ HOME: root, USERPROFILE: root }),
+  });
+  assert.strictEqual(result.status, 0, `install failed: ${result.stderr}`);
+
+  const settings = JSON.parse(fs.readFileSync(path.join(root, 'settings.json'), 'utf8'));
+  assert.deepEqual(settings.mcpServers.other, { command: 'my-tool', args: ['--flag'] },
+    "the user's pre-existing mcpServers entry must be preserved");
+  assert.ok(settings.mcpServers.gsd, 'the gsd companion entry must also be present');
+});
+
+// ---------------------------------------------------------------------------
+// Uninstall — symmetric cleanup for the MCP companion entry.
+// ---------------------------------------------------------------------------
+
+test('augment --global uninstall removes only the GSD-owned mcpServers.gsd entry, preserving user data', (t) => {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-augment-uninstall-'));
+  t.after(() => cleanup(root));
+
+  const env = installerEnv({ HOME: root, USERPROFILE: root });
+  const installArgs = [INSTALL_SCRIPT, '--augment', '--global', '--config-dir', root];
+  const installResult = spawnSync(process.execPath, installArgs, { encoding: 'utf8', env });
+  assert.strictEqual(installResult.status, 0, `install failed: ${installResult.stderr}`);
+
+  // Seed user-owned data alongside GSD's contributions, post-install.
+  const settingsPath = path.join(root, 'settings.json');
+  const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+  settings.mcpServers['my-own-server'] = { command: 'my-tool', args: [] };
+  fs.writeFileSync(settingsPath, JSON.stringify(settings, null, 2) + '\n');
+
+  const uninstallArgs = [INSTALL_SCRIPT, '--augment', '--global', '--config-dir', root, '--uninstall'];
+  const uninstallResult = spawnSync(process.execPath, uninstallArgs, { encoding: 'utf8', env });
+  assert.strictEqual(uninstallResult.status, 0, `uninstall failed: ${uninstallResult.stderr}`);
+
+  const settingsAfter = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+  assert.equal(settingsAfter.mcpServers && settingsAfter.mcpServers.gsd, undefined, 'gsd MCP entry removed');
+  assert.deepEqual(settingsAfter.mcpServers['my-own-server'], { command: 'my-tool', args: [] },
+    'user MCP server preserved');
+});

tests/capability-registry.test.cjs

@@ -4453,11 +4453,12 @@ describe('ADR-857 phase 5f: cross-field consistency gate rejection tests (DEFECT
     }
   });
 
-  test('VALID_PERMISSION_WRITERS covers exactly {opencode, kilo}', () => {
+  test('VALID_PERMISSION_WRITERS covers exactly {opencode, kilo, antigravity}', () => {
     assert.ok(VALID_PERMISSION_WRITERS instanceof Set, 'Must be a Set');
-    assert.strictEqual(VALID_PERMISSION_WRITERS.size, 2, 'Must cover 2 permission writers');
+    assert.strictEqual(VALID_PERMISSION_WRITERS.size, 3, 'Must cover 3 permission writers');
     assert.ok(VALID_PERMISSION_WRITERS.has('opencode'), 'Must include opencode');
     assert.ok(VALID_PERMISSION_WRITERS.has('kilo'), 'Must include kilo');
+    assert.ok(VALID_PERMISSION_WRITERS.has('antigravity'), 'Must include antigravity (#2096)');
   });
 
   // Confirm the valid base fixture does NOT produce errors (sanity)

tests/codebuddy-upgrades.test.cjs

@@ -0,0 +1,128 @@
+'use strict';
+
+/**
+ * CodeBuddy capability UPGRADES — ADR-1239 / #2098 (EoS/codebuddy).
+ *
+ * Drives the user-reachable surface (spawned `bin/install.js` via
+ * `runMinimalInstall`) plus a direct negotiation-contract check to prove the
+ * two real upgrades CodeBuddy contributes as part of the EoS migration:
+ *
+ *   UPGRADE 1 — extended hook events: CodeBuddy's `extendedHookEvents` was
+ *   previously `[]` (none of the 4 extended events were wired). This PR
+ *   wires all four — `SubagentStop`/`Stop`/`PreCompact`/`SubagentStart` —
+ *   into `extendedHookEvents` (mirrors qwen #2092 / kimi exactly — same 4
+ *   events), so a live install registers all four as hooks in settings.json
+ *   routed through gsd-context-monitor.js, giving CodeBuddy the
+ *   subagent-lifecycle + stop/compact hooks it previously lacked.
+ *
+ *   UPGRADE 2 — dispatch.background: CodeBuddy's capability.json already
+ *   declares `dispatch.background: true`, which legitimately EXCEEDS the
+ *   `declarative-cli` profile baseline (`false`, per
+ *   `PROFILE_BASELINES['declarative-cli']` in src/host-integration.cts).
+ *   NO agent-file/frontmatter change is involved — the CodeBuddy CLI has no
+ *   background-dispatch frontmatter field (agentMode/enabledAutoRun are
+ *   IDE-only; verified via codebuddy.ai/docs/cli/sub-agents). This is
+ *   surfaced purely through the negotiated contract: a documented `true`
+ *   value must survive negotiation without a downgrade warning.
+ */
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const { runMinimalInstall } = require('./helpers/install-shared.cjs');
+const { cleanup } = require('./helpers.cjs');
+const {
+  profileOf,
+  negotiateHostCapabilities,
+  PROFILE_BASELINES,
+} = require('../gsd-core/bin/lib/host-integration.cjs');
+
+const CODEBUDDY_CAP = JSON.parse(
+  fs.readFileSync(path.join(__dirname, '..', 'capabilities', 'codebuddy', 'capability.json'), 'utf8'),
+);
+const CODEBUDDY_AXES = CODEBUDDY_CAP.runtime.hostIntegration;
+
+// ---------------------------------------------------------------------------
+// UPGRADE 1: extended hook events — all 4 newly-wired events' live-install coverage
+// ---------------------------------------------------------------------------
+
+test('capabilities/codebuddy/capability.json extendedHookEvents contains exactly the 4 documented events', () => {
+  const events = CODEBUDDY_CAP.runtime.extendedHookEvents;
+  assert.deepEqual(events, ['SubagentStop', 'Stop', 'PreCompact', 'SubagentStart']);
+  assert.equal(events.length, 4);
+});
+
+test('codebuddy --global: settings.json wires all 4 newly-added extended hook events to the GSD context-monitor hook (UPGRADE 1)', (t) => {
+  const { configDir, root } = runMinimalInstall({ runtime: 'codebuddy', scope: 'global' });
+  t.after(() => cleanup(root));
+
+  const settingsPath = path.join(configDir, 'settings.json');
+  assert.ok(fs.existsSync(settingsPath), `${settingsPath} must exist`);
+  const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+
+  // All 4 events were newly wired by this PR — codebuddy's extendedHookEvents
+  // was previously [], so none of these existed before #2098.
+  const NEWLY_WIRED_EXTENDED_EVENTS = ['SubagentStop', 'Stop', 'PreCompact', 'SubagentStart'];
+
+  const entries = NEWLY_WIRED_EXTENDED_EVENTS.map((eventName) => {
+    const eventHooks = settings.hooks && settings.hooks[eventName];
+    assert.ok(Array.isArray(eventHooks) && eventHooks.length > 0,
+      `settings.hooks.${eventName} must exist and be non-empty`);
+    const entry = eventHooks[0].hooks[0];
+    assert.ok(entry.command.includes('gsd-context-monitor'),
+      `${eventName} command must reference gsd-context-monitor.js, got: ${entry.command}`);
+    assert.equal(entry.timeout, 10, `${eventName} entry must have timeout 10`);
+    return entry;
+  });
+
+  const [stopEntry, ...restEntries] = entries;
+  for (const entry of restEntries) {
+    assert.equal(entry.command, stopEntry.command,
+      'all 4 newly-wired extended events must wire the same gsd-context-monitor command');
+  }
+});
+
+test('a runtime whose extendedHookEvents omits SubagentStart does NOT get one (descriptor-gated, not a global default)', (t) => {
+  const { configDir, root } = runMinimalInstall({ runtime: 'claude', scope: 'global' });
+  t.after(() => cleanup(root));
+
+  const settingsPath = path.join(configDir, 'settings.json');
+  const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+
+  assert.ok(
+    settings.hooks && Array.isArray(settings.hooks.SubagentStop) && settings.hooks.SubagentStop.length > 0,
+    'claude must have SubagentStop wired (sanity — proves hooks ARE configured)',
+  );
+  assert.ok(
+    !settings.hooks || settings.hooks.SubagentStart === undefined,
+    "claude must NOT have SubagentStart wired — it is not in claude's extendedHookEvents",
+  );
+});
+
+// ---------------------------------------------------------------------------
+// UPGRADE 2: dispatch.background negotiation — documented true survives,
+// exceeding the declarative-cli profile baseline. No agent-file/frontmatter
+// change; caller-side invocation param only (no code path emits it).
+// ---------------------------------------------------------------------------
+
+test("codebuddy classifies as the 'declarative-cli' profile, whose baseline dispatch.background is false", () => {
+  assert.equal(profileOf(CODEBUDDY_AXES), 'declarative-cli');
+  assert.equal(PROFILE_BASELINES['declarative-cli'].dispatch.background, false,
+    'sanity: the declarative-cli baseline is false — codebuddy legitimately exceeds it');
+});
+
+test('negotiateHostCapabilities surfaces codebuddy\'s documented dispatch.background:true with no downgrade warning (UPGRADE 2)', () => {
+  assert.equal(CODEBUDDY_AXES.dispatch.background, true,
+    'sanity: the descriptor declares dispatch.background: true (documented, not undocumented)');
+
+  const { effective, warnings } = negotiateHostCapabilities(CODEBUDDY_AXES);
+
+  assert.equal(effective.dispatch.background, true,
+    'a documented true value must survive negotiation, exceeding the declarative-cli baseline of false');
+  assert.ok(
+    !warnings.some((w) => w.includes('dispatch.background')),
+    `no warning may be raised for the documented dispatch.background axis, got: ${JSON.stringify(warnings)}`,
+  );
+});

tests/declarative-reference-antigravity.test.cjs

@@ -1,3 +1,4 @@
+// allow-test-rule: structural-regression-guard — AC2 requires asserting no `runtime === 'antigravity'` string-equality branch (nor an `isAntigravity` helper, nor a `canonical === 'antigravity'` branch) remains in bin/install.js, src/runtime-artifact-conversion.cts, src/shell-command-projection.cts, and src/runtime-name-policy.cts — the descriptor-migration contract is a property of the source text, so a source-grep is the only faithful check (#2096)
 'use strict';
 
 /**
@@ -15,6 +16,17 @@
  * profile via profileOf, (2) confirms the public adapter classifies it as
  * declarative, and (3) round-trips a real install proving a gsd command surface
  * is emitted through the same engine the adapter delegates to.
+ *
+ * #2096 (EoS/antigravity) additions: negotiation fails CLOSED on a corrupted
+ * descriptor, the 4 still-`undocumented` dispatch sub-axes (namedDispatch/
+ * nested/maxDepth/backgroundDispatch) degrade to the most-restrictive known
+ * value (never their optimistic value), the validator accepts the negotiated
+ * subagentToolkit:'full' + permissionWriter:'antigravity' upgrade, and the
+ * hardcoded `runtime === 'antigravity'` / `isAntigravity` / `canonical ===
+ * 'antigravity'` branches are retired from the folded modules (folded into
+ * descriptor-driven `runtime.hostBehaviors` + `runtime.hostIntegration`).
+ * UPGRADE 1 (permission-writer) + UPGRADE 2 (MCP companion) live-install
+ * coverage is in tests/antigravity-upgrades.test.cjs — not duplicated here.
  */
 
 const { test, before } = require('node:test');
@@ -23,12 +35,20 @@ const fs = require('node:fs');
 const path = require('node:path');
 const { execFileSync } = require('node:child_process');
 
-const { profileOf } = require('../gsd-core/bin/lib/host-integration.cjs');
+const {
+  profileOf,
+  negotiateHostCapabilities,
+  PROFILE_BASELINES,
+  UNDOCUMENTED,
+} = require('../gsd-core/bin/lib/host-integration.cjs');
+const { validateCapability } = require('../gsd-core/bin/lib/capability-validator.cjs');
 const { createDeclarativeAdapter } = require('../gsd-core/bin/lib/adapter-declarative.cjs');
 const { cleanup } = require('./helpers.cjs');
 const { walk, runMinimalInstall, BUILD_SCRIPT } = require('./helpers/install-shared.cjs');
 
 const DESC = path.join(__dirname, '..', 'capabilities', 'antigravity', 'capability.json');
+const ANTIGRAVITY_CAP = JSON.parse(fs.readFileSync(DESC, 'utf8'));
+const ANTIGRAVITY_AXES = ANTIGRAVITY_CAP.runtime.hostIntegration;
 
 // hooks/dist is gitignored and built (mirrors golden-install-parity harness).
 before(() => {
@@ -66,6 +86,130 @@ test('a real Antigravity install emits a gsd command/skill surface (invocable)',
   }
 });
 
+// ---------------------------------------------------------------------------
+// #2096 EoS/antigravity — AC3/AC5: fail-closed negotiation + validator
+// acceptance + the folded descriptor (mirrors kimi/codex reference tests).
+// ---------------------------------------------------------------------------
+
+// -- AC5: negotiation fails CLOSED on a corrupted descriptor ------------------
+
+test('negotiateHostCapabilities never throws for antigravity, even fully corrupted', () => {
+  assert.doesNotThrow(() => negotiateHostCapabilities({}));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...ANTIGRAVITY_AXES, embeddingMode: UNDOCUMENTED }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...ANTIGRAVITY_AXES, embeddingMode: 'future-unknown' }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...ANTIGRAVITY_AXES, dispatch: 'corrupted-not-an-object' }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...ANTIGRAVITY_AXES, dispatch: { ...ANTIGRAVITY_AXES.dispatch, maxDepth: 'not-a-number' } }));
+});
+
+test('a partial/empty antigravity descriptor degrades to the safe floor, not the declarative-cli baseline', () => {
+  const result = negotiateHostCapabilities({});
+  assert.equal(result.effective.embeddingMode, 'declarative', 'omitted embeddingMode degrades closed');
+  assert.equal(result.effective.hookBus, 'none');
+  assert.notDeepEqual(result.effective, PROFILE_BASELINES['declarative-cli']);
+  assert.ok(result.warnings.length > 0);
+});
+
+// AC-specific: the 4 still-undocumented dispatch sub-axes must degrade to the
+// most-restrictive KNOWN value, not their optimistic value. Real values below
+// were confirmed via:
+//   node -e "const {negotiateHostCapabilities}=require('./gsd-core/bin/lib/host-integration.cjs');
+//            const cap=require('./capabilities/antigravity/capability.json');
+//            console.log(negotiateHostCapabilities(cap.runtime.hostIntegration).effective.dispatch)"
+// -> { namedDispatch:false, nested:false, maxDepth:0, background:false, subagentToolkit:'full', backgroundDispatch:false }
+test("antigravity's 4 still-undocumented dispatch sub-axes (namedDispatch/nested/maxDepth/backgroundDispatch) degrade to the most-restrictive known value, not their optimistic value", () => {
+  // Sanity: the descriptor itself still declares these 4 as the undocumented
+  // sentinel. subagentToolkit is the ONE dispatch axis Context7 confirmed as
+  // 'full' (antigravity.google/docs/cli/features) — it is deliberately NOT
+  // part of this still-undocumented set.
+  assert.equal(ANTIGRAVITY_AXES.dispatch.namedDispatch, 'undocumented');
+  assert.equal(ANTIGRAVITY_AXES.dispatch.nested, 'undocumented');
+  assert.equal(ANTIGRAVITY_AXES.dispatch.maxDepth, 'undocumented');
+  assert.equal(ANTIGRAVITY_AXES.dispatch.backgroundDispatch, 'undocumented');
+  assert.equal(ANTIGRAVITY_AXES.dispatch.subagentToolkit, 'full', 'sanity: subagentToolkit is documented, not part of the undocumented set');
+
+  const { effective, warnings } = negotiateHostCapabilities(ANTIGRAVITY_AXES);
+
+  assert.equal(effective.dispatch.namedDispatch, false, 'undocumented namedDispatch must degrade to false, never true');
+  assert.equal(effective.dispatch.nested, false, 'undocumented nested must degrade to false, never true');
+  assert.equal(effective.dispatch.maxDepth, 0, 'undocumented maxDepth must degrade to 0, never -1/unbounded');
+  assert.equal(effective.dispatch.backgroundDispatch, false, 'undocumented backgroundDispatch must degrade to false, never true');
+
+  // subagentToolkit is documented 'full' (not undocumented) — it is trusted
+  // and survives negotiation, in contrast to the 4 sub-axes above.
+  assert.equal(effective.dispatch.subagentToolkit, 'full', "documented 'full' subagentToolkit is trusted, unlike the undocumented sub-axes");
+
+  // background is declared `true` (documented, not undocumented) but the
+  // struct-consistency cap in negotiateHostCapabilities still zeroes it
+  // because its sibling namedDispatch degraded to false — a host-declared
+  // `true` never overrides the fail-closed floor forced by a degraded axis.
+  assert.equal(effective.dispatch.background, false, 'background is capped to false once namedDispatch degrades closed');
+
+  for (const axis of ['namedDispatch', 'nested', 'backgroundDispatch']) {
+    assert.ok(
+      warnings.some((w) => w.includes(`dispatch.${axis}`) && w.includes('undocumented')),
+      `a warning must be raised for the undocumented dispatch.${axis} axis`,
+    );
+  }
+  assert.ok(
+    warnings.some((w) => w.includes('dispatch.maxDepth')),
+    'a warning must be raised for the undocumented dispatch.maxDepth axis (reported as missing/non-number)',
+  );
+});
+
+// -- AC3: the validator accepts the negotiated/folded descriptor values ------
+
+test('capabilities/antigravity/capability.json validates — subagentToolkit "full" + permissionWriter "antigravity" are accepted', () => {
+  const errors = validateCapability(ANTIGRAVITY_CAP, 'antigravity');
+  assert.deepEqual(errors, [], `validateCapability must return no errors, got: ${JSON.stringify(errors)}`);
+  assert.equal(ANTIGRAVITY_AXES.dispatch.subagentToolkit, 'full');
+  assert.equal(ANTIGRAVITY_CAP.runtime.permissionWriter, 'antigravity');
+});
+
+// -- AC2: the folded-in hostBehaviors + subagentToolkit upgrade --------------
+
+test('antigravity descriptor declares runtime.hostBehaviors (the folded-in behaviors) + the subagentToolkit upgrade', () => {
+  const hb = ANTIGRAVITY_CAP.runtime.hostBehaviors;
+  assert.ok(hb && typeof hb === 'object');
+  assert.equal(hb.reviewerCli, true);
+  assert.equal(hb.projectInstructionFile, 'GEMINI.md');
+  assert.equal(hb.noPathRewrite, true);
+  assert.equal(hb.hookPathStyle, 'raw');
+  assert.equal(ANTIGRAVITY_AXES.dispatch.subagentToolkit, 'full',
+    'subagentToolkit flipped undocumented -> full (antigravity.google/docs/cli/features)');
+});
+
+// -- AC2: the hardcoded branches are retired across all folded modules -------
+
+test('no `runtime === "antigravity"` string-equality branch (nor `isAntigravity` / `canonical === "antigravity"`) remains in the descriptor-migrated modules (AC2)', () => {
+  const strip = (src) => src
+    .replace(/\/\*[\s\S]*?\*\//g, '')
+    .replace(/\/\/[^\r\n]*/g, '')
+    .replace(/`[^`]*`/g, '');
+  const repoRoot = path.join(__dirname, '..');
+  const files = [
+    path.join(repoRoot, 'bin', 'install.js'),
+    path.join(repoRoot, 'src', 'runtime-artifact-conversion.cts'),
+    path.join(repoRoot, 'src', 'shell-command-projection.cts'),
+    path.join(repoRoot, 'src', 'runtime-name-policy.cts'),
+  ];
+  for (const file of files) {
+    const src = fs.readFileSync(file, 'utf8');
+    const stripped = strip(src);
+
+    const eqOffenders = stripped.match(/runtime\s*[!=]==\s*'antigravity'/g) || [];
+    assert.deepEqual(eqOffenders, [],
+      `AC2: no hardcoded runtime==='antigravity' branch may remain in ${path.relative(repoRoot, file)}; found: ${eqOffenders.join(', ')}`);
+
+    const isAntigravityHits = stripped.match(/\bisAntigravity\b/g) || [];
+    assert.deepEqual(isAntigravityHits, [],
+      `AC2: no isAntigravity helper may remain in ${path.relative(repoRoot, file)}; found ${isAntigravityHits.length} occurrence(s)`);
+
+    const canonicalOffenders = stripped.match(/canonical\s*===\s*'antigravity'/g) || [];
+    assert.deepEqual(canonicalOffenders, [],
+      `AC2: no canonical==='antigravity' branch may remain in ${path.relative(repoRoot, file)}; found: ${canonicalOffenders.join(', ')}`);
+  }
+});
+
 
 // ────────────────────────────────────────────────────────────────────────
 // Folded from tests/bug-3608-antigravity-update-runtime-classification.test.cjs — consolidation epic #1969 (B3 #1972)

tests/declarative-reference-augment.test.cjs

@@ -0,0 +1,202 @@
+// allow-test-rule: structural-regression-guard — the descriptor-migration contract (no `runtime === 'augment'` / `isAugment`-as-conversion-branch dispatch logic left in the folded modules) is a property of the source text itself, so a source-grep is the only faithful check (#2097, mirrors tests/declarative-reference-antigravity.test.cjs #2096 AC2 guard).
+'use strict';
+
+/**
+ * Declarative reference host coverage — Augment Code (ADR-1239 / #2097
+ * EoS/augment migration).
+ *
+ * Augment is already a declarative-CLI host (nested-skill artifact layout,
+ * settings-json hook surface, Claude hook event dialect). #2097 folds its two
+ * remaining runtime-literal branches in src/runtime-artifact-conversion.cts
+ * onto descriptor-driven dispatch (runtime.hostBehaviors.commandBodyConverter)
+ * and deletes 2 dead-code sites in bin/install.js — mirroring the Antigravity
+ * migration (#2096) structure without duplicating its Antigravity-specific
+ * (GEMINI.md / reviewerCli / noPathRewrite) assertions.
+ *
+ * UPGRADE 3 (MCP companion, settings.json-hosted) live-install coverage is in
+ * tests/augment-upgrades.test.cjs — not duplicated here.
+ */
+
+const { test, before } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const { execFileSync } = require('node:child_process');
+
+const {
+  profileOf,
+  negotiateHostCapabilities,
+  UNDOCUMENTED,
+} = require('../gsd-core/bin/lib/host-integration.cjs');
+const { createDeclarativeAdapter } = require('../gsd-core/bin/lib/adapter-declarative.cjs');
+const { cleanup } = require('./helpers.cjs');
+const { walk, runMinimalInstall, BUILD_SCRIPT } = require('./helpers/install-shared.cjs');
+
+const DESC = path.join(__dirname, '..', 'capabilities', 'augment', 'capability.json');
+const AUGMENT_CAP = JSON.parse(fs.readFileSync(DESC, 'utf8'));
+const AUGMENT_AXES = AUGMENT_CAP.runtime.hostIntegration;
+
+// hooks/dist is gitignored and built (mirrors golden-install-parity harness).
+before(() => {
+  execFileSync(process.execPath, [BUILD_SCRIPT], { encoding: 'utf-8', stdio: 'pipe' });
+});
+
+test('Augment classifies as the declarative-cli profile (profileOf)', () => {
+  const desc = JSON.parse(fs.readFileSync(DESC, 'utf8'));
+  const axes = desc.runtime.hostIntegration;
+  assert.ok(axes && axes.embeddingMode, 'augment descriptor declares hostIntegration axes');
+  assert.equal(profileOf(axes), 'declarative-cli', 'Augment is a declarative-CLI host');
+});
+
+test('the public declarative adapter classifies Augment as a declarative host', () => {
+  const adapter = createDeclarativeAdapter({ runtime: 'augment' });
+  assert.equal(adapter.kind, 'declarative');
+  assert.equal(adapter.runtime, 'augment');
+  assert.equal(typeof adapter.install, 'function');
+  assert.equal(typeof adapter.uninstall, 'function');
+});
+
+test('a real Augment install emits a gsd command/skill surface (invocable)', () => {
+  const { configDir, root } = runMinimalInstall({ runtime: 'augment', scope: 'global' });
+  try {
+    const files = walk(configDir);
+    assert.ok(files.length > 0, 'install must emit artifacts');
+    const gsdSurface = files.filter((f) => /gsd/i.test(path.relative(configDir, f)));
+    assert.ok(gsdSurface.length > 0,
+      'install must emit a gsd command/skill surface (declarative reference)');
+  } finally {
+    cleanup(root);
+  }
+});
+
+// ---------------------------------------------------------------------------
+// #2097 EoS/augment — fail-closed negotiation + folded dispatch sub-axes
+// (mirrors the antigravity/kimi reference tests).
+// ---------------------------------------------------------------------------
+
+test('negotiateHostCapabilities never throws for augment, even fully corrupted', () => {
+  assert.doesNotThrow(() => negotiateHostCapabilities({}));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...AUGMENT_AXES, embeddingMode: UNDOCUMENTED }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...AUGMENT_AXES, embeddingMode: 'future-unknown' }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...AUGMENT_AXES, dispatch: 'corrupted-not-an-object' }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...AUGMENT_AXES, dispatch: { ...AUGMENT_AXES.dispatch, maxDepth: 'not-a-number' } }));
+});
+
+// AC-style proof: the 3 still-`undocumented` dispatch sub-axes (nested/
+// maxDepth/backgroundDispatch) must degrade to the most-restrictive KNOWN
+// value, never their optimistic value — mirrors antigravity's equivalent
+// test, but Augment documents namedDispatch/background (unlike antigravity),
+// so only 3 sub-axes are undocumented here, not 4. Real values confirmed via:
+//   node -e "const {negotiateHostCapabilities}=require('./gsd-core/bin/lib/host-integration.cjs');
+//            const cap=require('./capabilities/augment/capability.json');
+//            console.log(negotiateHostCapabilities(cap.runtime.hostIntegration).effective.dispatch)"
+// -> { namedDispatch:true, nested:false, maxDepth:0, background:true, subagentToolkit:'full', backgroundDispatch:false }
+test("augment's 3 still-undocumented dispatch sub-axes (nested/maxDepth/backgroundDispatch) degrade to the most-restrictive known value, not their optimistic value", () => {
+  // Sanity: the descriptor itself still declares these 3 as the undocumented
+  // sentinel, while namedDispatch/background/subagentToolkit are documented.
+  assert.equal(AUGMENT_AXES.dispatch.nested, 'undocumented');
+  assert.equal(AUGMENT_AXES.dispatch.maxDepth, 'undocumented');
+  assert.equal(AUGMENT_AXES.dispatch.backgroundDispatch, 'undocumented');
+  assert.equal(AUGMENT_AXES.dispatch.namedDispatch, true, 'sanity: namedDispatch is documented, not part of the undocumented set');
+  assert.equal(AUGMENT_AXES.dispatch.background, true, 'sanity: background is documented, not part of the undocumented set');
+  assert.equal(AUGMENT_AXES.dispatch.subagentToolkit, 'full', 'sanity: subagentToolkit is documented, not part of the undocumented set');
+
+  const { effective, warnings } = negotiateHostCapabilities(AUGMENT_AXES);
+
+  assert.equal(effective.dispatch.nested, false, 'undocumented nested must degrade to false, never true');
+  assert.equal(effective.dispatch.maxDepth, 0, 'undocumented maxDepth must degrade to 0, never -1/unbounded');
+  assert.equal(effective.dispatch.backgroundDispatch, false, 'undocumented backgroundDispatch must degrade to false, never true');
+
+  // namedDispatch/background/subagentToolkit are documented — they are
+  // trusted and survive negotiation unchanged, in contrast to the 3
+  // undocumented sub-axes above. Augment's negotiation must NOT flatten
+  // dispatch the way a fully-undocumented descriptor (e.g. antigravity's
+  // namedDispatch) would.
+  assert.equal(effective.dispatch.namedDispatch, true, "documented 'true' namedDispatch is trusted, unlike the undocumented sub-axes");
+  assert.equal(effective.dispatch.background, true, "documented 'true' background is trusted — not capped to false, since namedDispatch did not degrade closed");
+  assert.equal(effective.dispatch.subagentToolkit, 'full', "documented 'full' subagentToolkit is trusted, unlike the undocumented sub-axes");
+
+  for (const axis of ['nested', 'backgroundDispatch']) {
+    assert.ok(
+      warnings.some((w) => w.includes(`dispatch.${axis}`) && w.includes('undocumented')),
+      `a warning must be raised for the undocumented dispatch.${axis} axis`,
+    );
+  }
+  assert.ok(
+    warnings.some((w) => w.includes('dispatch.maxDepth')),
+    'a warning must be raised for the undocumented dispatch.maxDepth axis (reported as missing/non-number)',
+  );
+});
+
+// ---------------------------------------------------------------------------
+// #2097 AC2-equivalent — the hardcoded conversion-dispatch branches folded by
+// this migration are retired from the folded modules.
+//
+// Unlike antigravity (#2096), where `isAntigravity` was eliminated from
+// bin/install.js entirely, Augment's `isAugment` flag legitimately remains
+// (destructured from runtimeFlags() and used for non-conversion verification
+// logic — e.g. counting installed commands/ files). So this guard does NOT
+// assert zero `isAugment` occurrences (that would be a false failure); it
+// asserts no `isAugment` occurrence gates a call to an Augment *converter*
+// function (the exact shape of the dead branch this migration deleted:
+// `else if (isAugment) { content = convertClaudeAgentToAugmentAgent(content); }`).
+// The switch `case 'augment':` label in _applyRuntimeRewrites is intentionally
+// NOT flagged — it does plain dirName-derived path-prefix rewriting (same as
+// the still-`case`-labeled trae/codebuddy/cursor/windsurf branches), not
+// conversion-function dispatch, and antigravity's own guard tolerates its
+// `case 'antigravity':` label for the identical reason (its regex only
+// matches `runtime === 'x'`, never a `case` label).
+// ---------------------------------------------------------------------------
+
+test('no `runtime === "augment"` string-equality branch remains in the descriptor-migrated modules', () => {
+  const strip = (src) => src
+    .replace(/\/\*[\s\S]*?\*\//g, '')
+    .replace(/\/\/[^\r\n]*/g, '')
+    .replace(/`[^`]*`/g, '');
+  const repoRoot = path.join(__dirname, '..');
+  const files = [
+    path.join(repoRoot, 'bin', 'install.js'),
+    path.join(repoRoot, 'src', 'runtime-artifact-conversion.cts'),
+  ];
+  for (const file of files) {
+    const src = fs.readFileSync(file, 'utf8');
+    const stripped = strip(src);
+    const eqOffenders = stripped.match(/runtime\s*[!=]==\s*'augment'/g) || [];
+    assert.deepEqual(eqOffenders, [],
+      `no hardcoded runtime==='augment' branch may remain in ${path.relative(repoRoot, file)}; found: ${eqOffenders.join(', ')}`);
+  }
+});
+
+test('no `isAugment` occurrence gates a call to an Augment converter function (the deleted dead-code shape)', () => {
+  const converterNames = [
+    'convertClaudeAgentToAugmentAgent',
+    'convertClaudeToAugmentMarkdown',
+    'convertClaudeCommandToAugmentSkill',
+    'convertSlashCommandsToAugmentSkillMentions',
+  ];
+  const converterCallPattern = new RegExp(`(${converterNames.join('|')})\\s*\\(`);
+
+  const file = path.join(__dirname, '..', 'bin', 'install.js');
+  const lines = fs.readFileSync(file, 'utf8').split(/\r?\n/);
+  const offenders = [];
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i];
+    // Only condition-position occurrences count (`if (isAugment)` / `else if
+    // (isAugment)`), not the runtimeFlags() destructure or unrelated reads.
+    if (!/(?:if|else if)\s*\(\s*isAugment\s*\)/.test(line)) continue;
+    const window = lines.slice(i, i + 4).join('\n');
+    if (converterCallPattern.test(window)) {
+      offenders.push(`line ${i + 1}: ${line.trim()}`);
+    }
+  }
+  assert.deepEqual(offenders, [],
+    `no isAugment-gated call to an Augment converter may remain in bin/install.js; found: ${offenders.join(' | ')}`);
+});
+
+test('legitimate isAugment destructure/enumeration sites survive (not eliminated, unlike isAntigravity)', () => {
+  const file = path.join(__dirname, '..', 'bin', 'install.js');
+  const src = fs.readFileSync(file, 'utf8');
+  assert.ok(/isAugment/.test(src), 'isAugment must still be destructured from runtimeFlags() for non-conversion uses');
+  assert.ok(/_DESCRIPTOR_AGENTS_RUNTIMES\s*=\s*new Set\(\[[^\]]*'augment'/.test(src),
+    'augment must remain in _DESCRIPTOR_AGENTS_RUNTIMES (descriptor-driven agent layout)');
+});

tests/declarative-reference-codebuddy.test.cjs

@@ -0,0 +1,155 @@
+// allow-test-rule: structural-regression-guard — AC2: assert no `runtime === 'codebuddy'` string-equality branch, no `isCodebuddy` conversion helper, no `canonical === 'codebuddy'` branch remains in bin/install.js, src/runtime-artifact-conversion.cts, src/shell-command-projection.cts, src/runtime-name-policy.cts — a source-text property, so source-grep is the faithful check (#2098)
+'use strict';
+
+/**
+ * Declarative reference host — CodeBuddy (#2098 / ADR-1239 EoS).
+ *
+ * CodeBuddy already installs through the descriptor-driven artifactLayout
+ * (commands/skills/agents, each with a named `converter`), and its
+ * capability.json already declares `hostIntegration` + `dispatch` axes.
+ * Unlike antigravity/qwen (#2096/#2092), CodeBuddy was NOT migrated off a
+ * legacy runtime-keyed branch chain wholesale — issue #2098 found it was
+ * already descriptor-driven except for two residual `isCodebuddy` branches
+ * in bin/install.js:
+ *   1. a duplicate `commands/` slash-command output report (byte-identical
+ *      to the generic `hostBehaviors.reportCommandsDir` block already used
+ *      by Cursor) — folded onto `hostBehaviors.reportCommandsDir` and deleted.
+ *   2. a dead legacy agent-converter dispatch arm in the inline agent-copy
+ *      loop, unreachable because codebuddy is a member of
+ *      `_DESCRIPTOR_AGENTS_RUNTIMES` (installRuntimeArtifacts already wrote
+ *      the agents before that loop runs) — deleted outright.
+ *
+ * This test is the reference-host dogfood mirroring
+ * tests/declarative-reference-antigravity.test.cjs: it (1) classifies
+ * CodeBuddy's profile via profileOf, (2) confirms the public declarative
+ * adapter classifies it as declarative, (3) round-trips a real install
+ * proving a gsd command surface is emitted, (4) proves negotiation fails
+ * CLOSED on a corrupted descriptor, (5) proves the validator accepts the
+ * descriptor, and (6) source-greps the folded modules for the retired
+ * `isCodebuddy` branches (AC2).
+ *
+ * UPGRADE 1 (extended hook events) + UPGRADE 2 (dispatch.background
+ * negotiation) live-install coverage is in tests/codebuddy-upgrades.test.cjs
+ * — not duplicated here.
+ */
+
+const { test, before } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const { execFileSync } = require('node:child_process');
+
+const {
+  profileOf,
+  negotiateHostCapabilities,
+  PROFILE_BASELINES,
+  UNDOCUMENTED,
+} = require('../gsd-core/bin/lib/host-integration.cjs');
+const { validateCapability } = require('../gsd-core/bin/lib/capability-validator.cjs');
+const { createDeclarativeAdapter } = require('../gsd-core/bin/lib/adapter-declarative.cjs');
+const { cleanup } = require('./helpers.cjs');
+const { walk, runMinimalInstall, BUILD_SCRIPT } = require('./helpers/install-shared.cjs');
+
+const DESC = path.join(__dirname, '..', 'capabilities', 'codebuddy', 'capability.json');
+const CODEBUDDY_CAP = JSON.parse(fs.readFileSync(DESC, 'utf8'));
+const CODEBUDDY_AXES = CODEBUDDY_CAP.runtime.hostIntegration;
+
+// hooks/dist is gitignored and built (mirrors golden-install-parity harness).
+before(() => {
+  execFileSync(process.execPath, [BUILD_SCRIPT], { encoding: 'utf-8', stdio: 'pipe' });
+});
+
+test('CodeBuddy classifies as the declarative-cli reference profile (profileOf)', () => {
+  const desc = JSON.parse(fs.readFileSync(DESC, 'utf8'));
+  const axes = desc.runtime.hostIntegration;
+  assert.ok(axes && axes.embeddingMode, 'codebuddy descriptor declares hostIntegration axes');
+  assert.equal(profileOf(axes), 'declarative-cli',
+    'CodeBuddy is a Declarative-CLI host');
+});
+
+test('the public declarative adapter classifies CodeBuddy as a declarative host', () => {
+  const adapter = createDeclarativeAdapter({ runtime: 'codebuddy' });
+  assert.equal(adapter.kind, 'declarative');
+  assert.equal(adapter.runtime, 'codebuddy');
+  assert.equal(typeof adapter.install, 'function');
+  assert.equal(typeof adapter.uninstall, 'function');
+});
+
+test('a real CodeBuddy install emits a gsd command/skill surface (invocable)', () => {
+  const { configDir, root } = runMinimalInstall({ runtime: 'codebuddy', scope: 'global' });
+  try {
+    const files = walk(configDir);
+    assert.ok(files.length > 0, 'install must emit artifacts');
+    // CodeBuddy uses a flat commands/gsd-*.md slash-command surface
+    // (CONTEXT.md installer module; capabilities/codebuddy/capability.json
+    // artifactLayout `kind: "commands"`).
+    const gsdSurface = files.filter((f) => /gsd/i.test(path.relative(configDir, f)));
+    assert.ok(gsdSurface.length > 0,
+      'install must emit a gsd command/skill surface (declarative reference)');
+    const commandsDir = path.join(configDir, 'commands');
+    assert.ok(fs.existsSync(commandsDir), 'commands/ directory must exist');
+    const cmdFiles = fs.readdirSync(commandsDir)
+      .filter((f) => f.startsWith('gsd-') && f.endsWith('.md'));
+    assert.ok(cmdFiles.length > 0, 'commands/ must contain gsd-*.md slash commands');
+  } finally {
+    cleanup(root);
+  }
+});
+
+// ---------------------------------------------------------------------------
+// #2098 EoS/codebuddy — fail-closed negotiation + validator acceptance +
+// the folded descriptor (mirrors antigravity/qwen reference tests).
+// ---------------------------------------------------------------------------
+
+test('negotiateHostCapabilities never throws for codebuddy, even fully corrupted', () => {
+  assert.doesNotThrow(() => negotiateHostCapabilities({}));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...CODEBUDDY_AXES, embeddingMode: UNDOCUMENTED }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...CODEBUDDY_AXES, embeddingMode: 'future-unknown' }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...CODEBUDDY_AXES, dispatch: 'corrupted-not-an-object' }));
+  assert.doesNotThrow(() => negotiateHostCapabilities({ ...CODEBUDDY_AXES, dispatch: { ...CODEBUDDY_AXES.dispatch, maxDepth: 'not-a-number' } }));
+});
+
+test('a partial/empty codebuddy descriptor degrades to the safe floor, not the declarative-cli baseline', () => {
+  const result = negotiateHostCapabilities({});
+  assert.equal(result.effective.embeddingMode, 'declarative', 'omitted embeddingMode degrades closed');
+  assert.equal(result.effective.hookBus, 'none');
+  assert.notDeepEqual(result.effective, PROFILE_BASELINES['declarative-cli']);
+  assert.ok(result.warnings.length > 0);
+});
+
+test('capabilities/codebuddy/capability.json validates — no errors', () => {
+  const errors = validateCapability(CODEBUDDY_CAP, 'codebuddy');
+  assert.deepEqual(errors, [], `validateCapability must return no errors, got: ${JSON.stringify(errors)}`);
+});
+
+// -- AC2: the hardcoded branches are retired across all folded modules -------
+
+test('no `runtime === "codebuddy"` string-equality branch (nor `isCodebuddy` conversion helper / `canonical === "codebuddy"`) remains in the descriptor-migrated modules (AC2)', () => {
+  const strip = (src) => src
+    .replace(/\/\*[\s\S]*?\*\//g, '')
+    .replace(/\/\/[^\r\n]*/g, '')
+    .replace(/`[^`]*`/g, '');
+  const repoRoot = path.join(__dirname, '..');
+  const files = [
+    path.join(repoRoot, 'bin', 'install.js'),
+    path.join(repoRoot, 'src', 'runtime-artifact-conversion.cts'),
+    path.join(repoRoot, 'src', 'shell-command-projection.cts'),
+    path.join(repoRoot, 'src', 'runtime-name-policy.cts'),
+  ];
+  for (const file of files) {
+    const src = fs.readFileSync(file, 'utf8');
+    const stripped = strip(src);
+
+    const eqOffenders = stripped.match(/runtime\s*[!=]==\s*'codebuddy'/g) || [];
+    assert.deepEqual(eqOffenders, [],
+      `AC2: no hardcoded runtime==='codebuddy' branch may remain in ${path.relative(repoRoot, file)}; found: ${eqOffenders.join(', ')}`);
+
+    const isCodebuddyHits = stripped.match(/\bisCodebuddy\b/g) || [];
+    assert.deepEqual(isCodebuddyHits, [],
+      `AC2: no live isCodebuddy read may remain in ${path.relative(repoRoot, file)}; found ${isCodebuddyHits.length} occurrence(s)`);
+
+    const canonicalOffenders = stripped.match(/canonical\s*===\s*'codebuddy'/g) || [];
+    assert.deepEqual(canonicalOffenders, [],
+      `AC2: no canonical==='codebuddy' branch may remain in ${path.relative(repoRoot, file)}; found: ${canonicalOffenders.join(', ')}`);
+  }
+});

tests/fixtures/golden-install-parity/antigravity.json

@@ -336,6 +336,7 @@
   "hooks/lib/git-cmd.js": "268ba15992ca0b23",
   "hooks/lib/gsd-graphify-rebuild.sh": "66af89601074d2a9",
   "hooks/managed-hooks-registry.cjs": "721d696556b7509f",
+  "mcp_config.json": "9956d6a6e88a49e1",
   "package.json": "dbf8353f77358bc1",
   "scripts/changeset/README.md": "86ff89331dfd94b2",
   "scripts/changeset/cli.cjs": "68f92a344b199271",

tests/shell-command-projection-dispatch.test.cjs

@@ -343,9 +343,14 @@ describe('bug #1906: local hook commands use $CLAUDE_PROJECT_DIR', () => {
  * dir as cwd. Claude Code and others still use "$CLAUDE_PROJECT_DIR"/ (#1906).
  *
  * #1928: Google sunset Gemini CLI (2026-06-18) and the `gemini` runtime was
- * removed from GSD entirely. `projectLocalHookPrefix` now special-cases only
- * `antigravity` — an unrecognized runtime string like the former `'gemini'`
- * falls through to the default $CLAUDE_PROJECT_DIR-anchored prefix.
+ * removed from GSD entirely.
+ *
+ * #2096: `projectLocalHookPrefix` no longer special-cases `antigravity` by
+ * name — it branches on the caller-supplied `hookPathStyle` (sourced from
+ * the runtime's `hostBehaviors.hookPathStyle` descriptor field). An
+ * unrecognized runtime string like the former `'gemini'`, or any runtime
+ * that doesn't declare `hookPathStyle: 'raw'`, falls through to the default
+ * $CLAUDE_PROJECT_DIR-anchored prefix.
  */
 
 const { describe, test } = require('node:test');
@@ -357,7 +362,13 @@ const { projectLocalHookPrefix, projectShellCommandText } = projection;
 
 describe('bug #2557: Antigravity local hooks use relative paths (not $CLAUDE_PROJECT_DIR); gemini runtime removed (#1928)', () => {
   test('Antigravity local prefix is bare dirName', () => {
-    assert.equal(projectLocalHookPrefix({ runtime: 'antigravity', dirName: '.agents' }), '.agents');
+    // #2096: hookPathStyle is now the caller-supplied descriptor value
+    // (bin/install.js resolves it from hostBehaviors.hookPathStyle); the
+    // function itself no longer knows the runtime name 'antigravity'.
+    assert.equal(
+      projectLocalHookPrefix({ runtime: 'antigravity', dirName: '.agents', hookPathStyle: 'raw' }),
+      '.agents',
+    );
   });
 
   test('non-Antigravity local prefix remains $CLAUDE_PROJECT_DIR anchored', () => {
@@ -512,7 +523,13 @@ describe('bug #3439: shell projection module owns managed-hook policy and legacy
   });
 
   test('projectLocalHookPrefix centralizes runtime-specific project-dir interpolation policy', () => {
-    assert.equal(projectLocalHookPrefix({ runtime: 'antigravity', dirName: '.agents' }), '.agents');
+    // #2096: 'raw' hookPathStyle (descriptor-driven) is what produces the
+    // bare-dirName behavior now — the function no longer branches on the
+    // 'antigravity' runtime name itself.
+    assert.equal(
+      projectLocalHookPrefix({ runtime: 'antigravity', dirName: '.agents', hookPathStyle: 'raw' }),
+      '.agents',
+    );
     assert.equal(
       projectLocalHookPrefix({ runtime: 'claude', dirName: '.claude' }),
       '"$CLAUDE_PROJECT_DIR"/.claude',