diff --git a/.changeset/nimble-yaks-climb.md b/.changeset/nimble-yaks-climb.md
new file mode 100644
index 000000000..bf75a33b5
--- /dev/null
+++ b/.changeset/nimble-yaks-climb.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 2332
+---
+**Installing a non-Claude runtime no longer breaks Claude's model resolution in no-project sessions** — the installer writes `resolve_model_ids:"omit"` for non-alias runtimes into the machine-wide `~/.gsd/defaults.json`, which any runtime read back, so install order silently flipped Claude's adaptive tier aliases (executor→sonnet, planner→opus) to an empty model string. Resolution is now scoped to the runtime actually resolving, via a per-install `.gsd-runtime` marker: Claude ignores a global-defaults omit and keeps its tier aliases, non-alias runtimes still omit, and an explicit project-level `omit`/`true` is always honored. (#2297)
diff --git a/bin/install.js b/bin/install.js
index 41c0666c3..7180a9424 100755
--- a/bin/install.js
+++ b/bin/install.js
@@ -10880,6 +10880,22 @@ function install(isGlobal, runtime = DEFAULT_RUNTIME, options = {}) {
     failures.push('VERSION');
   }
 
+  // #2297: write a per-install runtime marker co-located with VERSION at
+  // <install>/gsd-core/.gsd-runtime. It gives resolveModelInternal a reliable
+  // "which runtime owns THIS install" signal in a no-project session (config.runtime
+  // is null and GSD_RUNTIME is not exported), so the shared ~/.gsd/defaults.json
+  // resolve_model_ids:"omit" policy (written below for non-alias runtimes only)
+  // applies ONLY when a non-alias runtime is actually resolving — a Claude session
+  // reads its own marker and keeps its tier aliases instead of inheriting another
+  // runtime's install-order-dependent "omit". See src/model-resolver.cts.
+  const runtimeMarkerDest = path.join(targetDir, 'gsd-core', '.gsd-runtime');
+  fs.writeFileSync(runtimeMarkerDest, `${runtime}\n`);
+  if (verifyFileInstalled(runtimeMarkerDest, '.gsd-runtime')) {
+    console.log(`  ${green}✓${reset} Wrote runtime marker (.gsd-runtime: ${runtime})`);
+  } else {
+    failures.push('.gsd-runtime');
+  }
+
   // Reusable: copy hooks/dist/ + hooks/lib/ into destRootDir, writing the
   // CommonJS package.json marker alongside them. Used below for the generic
   // configDir install path (guarded by hostBehaviors.skipSharedHooksInstall),
diff --git a/src/model-resolver.cts b/src/model-resolver.cts
index c475769f9..447a747be 100644
--- a/src/model-resolver.cts
+++ b/src/model-resolver.cts
@@ -10,7 +10,9 @@
  * epic #1267; callers import resolvers from model-resolver.cjs directly.
  *
  * Dependencies (leaf modules only):
- *   - node:fs / node:path (stdlib, not currently needed — included for future use)
+ *   - node:fs / node:path (read the per-install .gsd-runtime marker + project config for the #2297 omit gate)
+ *   - ./runtime-name-policy.cjs (resolveRuntimeNameFromCandidates — canonicalize the active runtime)
+ *   - ./planning-workspace.cjs  (planningDir — workstream/project-aware project-config path)
  *   - ./config-loader.cjs    (loadConfig)
  *   - ./configuration.cjs    (CONFIG_DEFAULTS as CANONICAL_CONFIG_DEFAULTS)
  *   - ./model-profiles.cjs   (MODEL_PROFILES, AGENT_TO_PHASE_TYPE, AGENT_DEFAULT_TIERS, VALID_AGENT_TIERS, nextTier)
@@ -30,6 +32,98 @@ const { MODEL_PROFILES, AGENT_TO_PHASE_TYPE, AGENT_DEFAULT_TIERS, VALID_AGENT_TI
 
 import { MODEL_ALIAS_MAP, RUNTIME_PROFILE_MAP, PROVIDER_PRESETS } from './model-catalog.cjs';
 
+import fs from 'node:fs';
+import path from 'node:path';
+import { resolveRuntimeNameFromCandidates } from './runtime-name-policy.cjs';
+// eslint-disable-next-line @typescript-eslint/no-require-imports
+import planningWorkspaceMod = require('./planning-workspace.cjs');
+const { planningDir } = planningWorkspaceMod;
+
+// ─── #2297: per-install runtime identity for the resolve_model_ids:"omit" gate ─
+//
+// The installer writes `resolve_model_ids:"omit"` into the SHARED
+// ~/.gsd/defaults.json for every runtime that lacks native model aliases (#1156).
+// Because that file is machine-wide, a non-Claude install would otherwise poison
+// a Claude no-project resolution into returning '' — silently defeating Claude's
+// adaptive tier aliases. The "omit" must therefore apply only when a runtime that
+// genuinely lacks native aliases is the one resolving.
+//
+// In a no-project session there is no `.planning/config.json` (so config.runtime
+// is null) and GSD_RUNTIME is not exported by gsd-core, so the only reliable
+// current-runtime signal is the per-install marker the installer co-locates next
+// to VERSION at <install>/gsd-core/.gsd-runtime (this file's dir is
+// <install>/gsd-core/bin/lib). Precedence for the gate: project config.runtime →
+// GSD_RUNTIME env (manual/CI override + test seam) → install marker → 'claude'.
+//
+// `claude` is currently the ONLY runtime with nativeModelAliases:true; a
+// registry-parity test guards this set so a future alias-capable runtime fails
+// loudly here instead of silently omitting.
+const RUNTIMES_WITH_NATIVE_ALIASES: ReadonlySet<string> = new Set(['claude']);
+
+let _installMarkerCache: string | null | undefined;
+function readInstallRuntimeMarker(): string | null {
+  if (_installMarkerCache !== undefined) return _installMarkerCache;
+  try {
+    const markerPath = path.join(__dirname, '..', '..', '.gsd-runtime');
+    const raw = fs.readFileSync(markerPath, 'utf8').trim();
+    _installMarkerCache = raw || null;
+  } catch {
+    // No marker: dev/source tree, or an install predating #2297. Fall through to
+    // the 'claude' default (keeps tier aliases — never worse than the bug).
+    _installMarkerCache = null;
+  }
+  return _installMarkerCache;
+}
+
+// Test seams for the install-marker rung (the dev/source tree has no marker, so
+// the file read always bottoms out at 'claude' — these let tests exercise the
+// third precedence rung and reset the module-level cache between cases).
+function _setInstallRuntimeMarkerForTests(value: string | null): void {
+  _installMarkerCache = value;
+}
+function _resetInstallRuntimeMarkerCacheForTests(): void {
+  _installMarkerCache = undefined;
+}
+
+// The runtime whose install is actually resolving, canonicalized so an alias or
+// case variant (e.g. "claude-code"/"Claude") cannot defeat the native-alias
+// check below (#2297 review). Precedence mirrors resolveRuntime()
+// (runtime-slash.cts): GSD_RUNTIME env → project config.runtime → per-install
+// .gsd-runtime marker → 'claude'.
+function resolveActiveRuntime(config: Record<string, unknown>): string {
+  return resolveRuntimeNameFromCandidates(
+    process.env['GSD_RUNTIME'],
+    config['runtime'],
+    readInstallRuntimeMarker(),
+  ) || 'claude';
+}
+
+// Did the PROJECT's own config (root `.planning/config.json` or the active
+// workstream/project override) explicitly set resolve_model_ids to "omit"?
+// Project config takes precedence over the shared ~/.gsd/defaults.json (#2297
+// out-of-scope guard + #2517 finding #4): an explicit project "omit" is honored
+// regardless of runtime, whereas an "omit" that came only from the global
+// defaults is ignored by native-alias runtimes. Workstream/project-scope aware
+// via planningDir (mirrors loadConfig's precedence: workstream value wins over
+// root); a plain read avoids loadConfig's normalization side effects.
+function projectExplicitlySetsOmit(cwd: string): boolean {
+  const wsDir = planningDir(cwd);
+  const rootDir = path.join(cwd, '.planning');
+  const layers = wsDir === rootDir ? [rootDir] : [wsDir, rootDir]; // workstream > root
+  for (const dir of layers) {
+    try {
+      const parsed = JSON.parse(fs.readFileSync(path.join(dir, 'config.json'), 'utf8')) as Record<string, unknown>;
+      const value = parsed?.['resolve_model_ids'];
+      // First layer that sets the key wins (matches loadConfig's deep-merge
+      // precedence). A layer that omits the key falls through to the next.
+      if (value !== undefined) return value === 'omit';
+    } catch {
+      // Absent/unreadable layer — try the next.
+    }
+  }
+  return false;
+}
+
 // ─── Model alias resolution ───────────────────────────────────────────────────
 
 interface TierEntryResolved {
@@ -277,8 +371,18 @@ function resolveModelInternal(cwd: string, agentType: string): string {
     if (entry?.model) return entry.model;
   }
 
-  // 4. resolve_model_ids: "omit"
-  if (config['resolve_model_ids'] === 'omit') {
+  // 4. resolve_model_ids: "omit" — runtime-aware (#2297). Honor "omit" when the
+  // PROJECT explicitly set it (user intent — project config wins, #2517 finding
+  // #4) OR when the active runtime genuinely lacks native model aliases. Only a
+  // native-alias runtime (Claude) ignores an "omit" that came solely from the
+  // SHARED ~/.gsd/defaults.json — the #2297 poisoning fix — and falls through to
+  // its tier aliases below. Active runtime: GSD_RUNTIME → config.runtime → the
+  // per-install .gsd-runtime marker → 'claude' (canonicalized).
+  // NOTE: a non-Claude runtime that HAS a populated runtime-tier map already
+  // returned its own model id at step 3 above, before this gate — for those the
+  // explicit-project-omit honoring here is moot (step 3 wins, by #2517 design).
+  if (config['resolve_model_ids'] === 'omit'
+      && (projectExplicitlySetsOmit(cwd) || !RUNTIMES_WITH_NATIVE_ALIASES.has(resolveActiveRuntime(config)))) {
     return '';
   }
 
@@ -292,7 +396,11 @@ function resolveModelInternal(cwd: string, agentType: string): string {
   if (tier === 'inherit') return 'inherit';
   const alias = tier;
 
-  if (config['resolve_model_ids']) {
+  // Only the explicit `true` opt-in materializes full model IDs (#1569). Guard
+  // against the loose-truthy check catching a "omit" that a native-alias runtime
+  // ignored above (#2297): "omit" must fall through to the tier ALIAS here, not
+  // be materialized into a full ID Claude's Agent tool cannot spawn.
+  if (config['resolve_model_ids'] === true) {
     return (MODEL_ALIAS_MAP as Record<string, string>)[alias!] || alias!;
   }
 
@@ -578,6 +686,8 @@ export = {
   resolveModelInternal,
   _resetModelPolicyWarningCacheForTests,
   _resetModelOverrideWarningCacheForTests,
+  _setInstallRuntimeMarkerForTests,
+  _resetInstallRuntimeMarkerCacheForTests,
   VALID_GRANULARITIES,
   resolveGranularityInternal,
   assertValidGranularityOverride,
diff --git a/tests/fix-2297-resolve-model-ids-runtime-scoping.test.cjs b/tests/fix-2297-resolve-model-ids-runtime-scoping.test.cjs
new file mode 100644
index 000000000..b50fd6e5a
--- /dev/null
+++ b/tests/fix-2297-resolve-model-ids-runtime-scoping.test.cjs
@@ -0,0 +1,411 @@
+/**
+ * Bug #2297 — `resolve_model_ids:"omit"` must be scoped to the ACTIVE runtime,
+ * not applied blindly whenever it appears anywhere in the merged config.
+ *
+ * Root cause (pre-fix): the installer writes `resolve_model_ids:"omit"` into the
+ * SHARED `~/.gsd/defaults.json` for every runtime that lacks native model
+ * aliases (#1156). Because that file is machine-wide, installing a non-Claude
+ * runtime (e.g. codex) on a box that also runs Claude poisoned Claude's
+ * no-project resolution: Claude would see `resolve_model_ids:"omit"` in the
+ * merged global defaults and return `''` instead of its tier aliases
+ * (opus/sonnet/haiku), silently defeating Claude's adaptive tier distinction.
+ *
+ * Fix (`src/model-resolver.cts` `resolveModelInternal`): the `"omit"` branch
+ * now returns `''` ONLY when either
+ *   (a) the PROJECT's own `.planning/config.json` explicitly sets
+ *       `resolve_model_ids:"omit"` (user intent — #2517 finding #4, unchanged), OR
+ *   (b) the ACTIVE runtime genuinely lacks native model aliases.
+ * A native-alias runtime (currently only `claude`) IGNORES an `"omit"` that
+ * came solely from the shared global defaults and falls through to its tier
+ * aliases. Active-runtime precedence: `process.env.GSD_RUNTIME` -> `config.runtime`
+ * -> per-install `.gsd-runtime` marker (absent in this dev/test tree, so the
+ * chain always bottoms out at `'claude'`) -> `'claude'` (all canonicalized).
+ *
+ * IMPORTANT (empirically verified — see dispatch report): the global-defaults
+ * merge path in `config-loader.cjs` (branch D: "no .planning/ at all") is ONLY
+ * exercised when the project directory has NO `.planning/` directory whatsoever.
+ * The moment a `.planning/` directory exists — even with an empty or absent
+ * `config.json` inside it — the loader takes a different branch that does NOT
+ * merge `~/.gsd/defaults.json` for these fields at all. So Group A below
+ * (which specifically exercises the global-defaults poisoning fix) uses BARE
+ * `fs.mkdtempSync` project dirs with no `.planning/` subdirectory. Group A #4,
+ * Group B, and Group C all need a real per-project config, so those DO create
+ * `.planning/config.json`.
+ */
+
+'use strict';
+
+const { describe, test, beforeEach, afterEach } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+const {
+  resolveModelInternal,
+  _setInstallRuntimeMarkerForTests,
+  _resetInstallRuntimeMarkerCacheForTests,
+} = require('../gsd-core/bin/lib/model-resolver.cjs');
+
+// ─── HOME / GSD_HOME / GSD_RUNTIME isolation ────────────────────────────────
+// config-loader.cjs reads global defaults from
+// path.join(process.env.GSD_HOME || os.homedir(), '.gsd', 'defaults.json').
+// Isolate both HOME and GSD_HOME to a fresh tmpdir per test (so a developer's
+// real ~/.gsd/defaults.json never bleeds into assertions), and save/restore
+// GSD_RUNTIME since several tests set it directly to drive the active-runtime
+// chain (#2297's second precedence rung). Also save/restore GSD_WORKSTREAM and
+// GSD_PROJECT (#2297 correctness-review hermeticity gap): planningDir() reads
+// both directly from process.env when its ws/project params are omitted, so an
+// ambient GSD_WORKSTREAM/GSD_PROJECT in a developer's shell could silently
+// redirect projectExplicitlySetsOmit()'s config-file reads to the wrong layer.
+let _origHome;
+let _origUserProfile;
+let _origGsdHome;
+let _origGsdRuntime;
+let _origGsdWorkstream;
+let _origGsdProject;
+let _isolatedHome;
+
+function isolateHome() {
+  _origHome = process.env.HOME;
+  _origUserProfile = process.env.USERPROFILE;
+  _origGsdHome = process.env.GSD_HOME;
+  _origGsdRuntime = process.env.GSD_RUNTIME;
+  _origGsdWorkstream = process.env.GSD_WORKSTREAM;
+  _origGsdProject = process.env.GSD_PROJECT;
+  _isolatedHome = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-2297-home-'));
+  process.env.HOME = _isolatedHome;
+  // Windows resolves the home dir from USERPROFILE, not HOME — set both so the
+  // isolation holds cross-platform (local/require-userprofile-with-home).
+  process.env.USERPROFILE = _isolatedHome;
+  process.env.GSD_HOME = _isolatedHome;
+  delete process.env.GSD_RUNTIME;
+  delete process.env.GSD_WORKSTREAM;
+  delete process.env.GSD_PROJECT;
+}
+
+function restoreHome() {
+  if (_origHome === undefined) delete process.env.HOME; else process.env.HOME = _origHome;
+  if (_origUserProfile === undefined) delete process.env.USERPROFILE; else process.env.USERPROFILE = _origUserProfile;
+  if (_origGsdHome === undefined) delete process.env.GSD_HOME; else process.env.GSD_HOME = _origGsdHome;
+  if (_origGsdRuntime === undefined) delete process.env.GSD_RUNTIME; else process.env.GSD_RUNTIME = _origGsdRuntime;
+  if (_origGsdWorkstream === undefined) delete process.env.GSD_WORKSTREAM; else process.env.GSD_WORKSTREAM = _origGsdWorkstream;
+  if (_origGsdProject === undefined) delete process.env.GSD_PROJECT; else process.env.GSD_PROJECT = _origGsdProject;
+  rmDir(_isolatedHome);
+  _isolatedHome = null;
+}
+
+function rmDir(dir) {
+  if (typeof dir !== 'string' || dir.length === 0) return;
+  // eslint-disable-next-line local/no-raw-rmsync-in-tests -- carries the same maxRetries/retryDelay budget as helpers.cleanup; used for both the isolated-home and bare project temp dirs
+  fs.rmSync(dir, { recursive: true, force: true, maxRetries: 10, retryDelay: 50 });
+}
+
+function writeGlobalDefaults(obj) {
+  fs.mkdirSync(path.join(_isolatedHome, '.gsd'), { recursive: true });
+  fs.writeFileSync(path.join(_isolatedHome, '.gsd', 'defaults.json'), JSON.stringify(obj, null, 2));
+}
+
+// Bare project dir with NO .planning/ subdirectory — needed to exercise the
+// config-loader's global-defaults merge branch (see file header).
+function mkProjNoPlanning() {
+  return fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-2297-proj-noplan-'));
+}
+
+// Project dir WITH a .planning/config.json — the normal "inside a project" path.
+function mkProjWithConfig(obj) {
+  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-2297-proj-'));
+  fs.mkdirSync(path.join(dir, '.planning'), { recursive: true });
+  fs.writeFileSync(path.join(dir, '.planning', 'config.json'), JSON.stringify(obj, null, 2));
+  return dir;
+}
+
+// ─── Group A: GLOBAL-defaults "omit" is runtime-scoped (the #2297 fix) ─────
+describe('#2297: global-defaults resolve_model_ids:"omit" is scoped to the active runtime', () => {
+  let projDir;
+  beforeEach(() => { isolateHome(); projDir = null; });
+  afterEach(() => { rmDir(projDir); restoreHome(); });
+
+  test('no runtime signal defaults to claude: executor and planner get distinct non-empty tier aliases (acceptance #3)', () => {
+    // Global defaults poison the shared file with "omit" (simulating a
+    // non-Claude runtime having been installed on this machine). With no
+    // .planning/config.json (no project) and no GSD_RUNTIME, the active
+    // runtime falls back to 'claude', which has native aliases and must
+    // ignore the poisoned global "omit" — the adaptive tier distinction
+    // between executor (sonnet) and planner (opus) must survive.
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+
+    const executor = resolveModelInternal(projDir, 'gsd-executor');
+    const planner = resolveModelInternal(projDir, 'gsd-planner');
+
+    assert.strictEqual(executor, 'sonnet');
+    assert.strictEqual(planner, 'opus');
+    assert.notStrictEqual(executor, '');
+    assert.notStrictEqual(planner, '');
+    assert.notStrictEqual(executor, planner);
+  });
+
+  test('GSD_RUNTIME="claude" explicitly: executor still resolves to "sonnet" (claude ignores global omit)', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    process.env.GSD_RUNTIME = 'claude';
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), 'sonnet');
+  });
+
+  test('GSD_RUNTIME="codex": a non-alias runtime still honors the global omit (acceptance #4)', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    process.env.GSD_RUNTIME = 'codex';
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), '');
+  });
+
+  // #2297 correctness-review BLOCKER: resolveActiveRuntime() must canonicalize
+  // its candidates via resolveRuntimeNameFromCandidates before checking
+  // RUNTIMES_WITH_NATIVE_ALIASES, or an alias/case variant of "claude" would
+  // fail the Set('claude').has() check and wrongly fall through to honoring the
+  // poisoned global omit. These would FAIL against a non-canonicalizing resolver.
+  test('GSD_RUNTIME="claude-code" (alias, not canonical "claude"): executor and planner still ignore the global omit', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    process.env.GSD_RUNTIME = 'claude-code';
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), 'sonnet');
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-planner'), 'opus');
+  });
+
+  test('GSD_RUNTIME="Claude" (case variant): executor still resolves to "sonnet" (canonicalization is case-insensitive)', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    process.env.GSD_RUNTIME = 'Claude';
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), 'sonnet');
+  });
+
+  test('project config.runtime="codex" (no resolve_model_ids in project) takes precedence over GSD_RUNTIME/marker in the active-runtime chain', () => {
+    // config.runtime is checked before GSD_RUNTIME / the install marker. This
+    // scenario uses a REAL project (.planning/config.json present), so the
+    // config-loader does NOT merge ~/.gsd/defaults.json for resolve_model_ids
+    // at all here (see file header) — resolution instead reaches the #2517
+    // runtime-tier path (step 3 in resolveModelInternal, which fires before
+    // the omit gate) and returns codex's native sonnet-tier model id directly,
+    // rather than the omit gate's ''. Verified empirically: the built resolver
+    // returns 'gpt-5.6-terra', not ''. Assert it is non-empty and NOT a claude
+    // alias, which is the property this test actually needs to guarantee
+    // (config.runtime, not GSD_RUNTIME/env, drove the resolution).
+    projDir = mkProjWithConfig({ runtime: 'codex' });
+    writeGlobalDefaults({ resolve_model_ids: 'omit' }); // irrelevant: not merged when .planning/ exists
+
+    const result = resolveModelInternal(projDir, 'gsd-executor');
+    assert.notStrictEqual(result, '');
+    assert.ok(
+      !['sonnet', 'opus', 'haiku'].includes(result),
+      `expected a non-claude-alias result for config.runtime="codex", got ${JSON.stringify(result)}`
+    );
+  });
+
+  test('install-order independence (acceptance #1/#2): a global omit poisoned by a prior non-Claude install does not affect Claude resolution, and Claude retains its adaptive tier distinction', () => {
+    // Resolution depends on the RESOLVING runtime (active runtime at call
+    // time), not on install order — installing codex (or any non-alias
+    // runtime) before/after Claude must never change what Claude itself
+    // resolves to. Global omit present, no project, no runtime signal ->
+    // default 'claude' -> tier aliases survive. Distinct from the first Group A
+    // test above: this asserts install-order independence AND, specifically,
+    // that executor/planner remain DIFFERENT tiers under the poisoned global
+    // omit — i.e. install order never collapses Claude's adaptive tier
+    // distinction into a single omitted value.
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+
+    const executor = resolveModelInternal(projDir, 'gsd-executor');
+    const planner = resolveModelInternal(projDir, 'gsd-planner');
+
+    assert.strictEqual(executor, 'sonnet');
+    assert.strictEqual(planner, 'opus');
+    assert.notStrictEqual(executor, planner, 'install-order poisoning must not collapse the adaptive tier distinction');
+  });
+});
+
+// ─── Group B: explicit PROJECT "omit" is still honored for EVERY runtime ───
+// (#2517 finding #4 — preserved, NOT changed by #2297.)
+describe('#2297: explicit project-level resolve_model_ids:"omit" is honored regardless of runtime', () => {
+  let projDir;
+  beforeEach(() => { isolateHome(); projDir = null; });
+  afterEach(() => { rmDir(projDir); restoreHome(); });
+
+  test('no runtime set, explicit project omit -> "" even though the default runtime is claude', () => {
+    projDir = mkProjWithConfig({ resolve_model_ids: 'omit' });
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-planner'), '');
+  });
+
+  test('runtime:"claude" + explicit project omit -> "" (mirrors #2517 finding #4)', () => {
+    projDir = mkProjWithConfig({ runtime: 'claude', resolve_model_ids: 'omit' });
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-planner'), '');
+  });
+});
+
+// ─── Group B2: projectExplicitlySetsOmit is workstream-scope aware (#2297) ──
+// The root .planning/config.json does NOT set resolve_model_ids, but the
+// ACTIVE workstream's own config.json does — projectExplicitlySetsOmit()
+// resolves via planningDir(cwd) (workstream layer wins over root, mirroring
+// loadConfig's precedence), so the workstream's explicit "omit" must still be
+// honored even though no global default and the default runtime (claude) would
+// otherwise have returned a tier alias.
+describe('#2297: explicit project-level "omit" is honored at the active-workstream config layer', () => {
+  let projDir;
+  let _origGsdWorkstreamForBlock;
+  beforeEach(() => {
+    isolateHome(); // clears GSD_WORKSTREAM/GSD_PROJECT as part of hermeticity
+    projDir = null;
+    _origGsdWorkstreamForBlock = process.env.GSD_WORKSTREAM;
+  });
+  afterEach(() => {
+    if (_origGsdWorkstreamForBlock === undefined) delete process.env.GSD_WORKSTREAM;
+    else process.env.GSD_WORKSTREAM = _origGsdWorkstreamForBlock;
+    rmDir(projDir);
+    restoreHome();
+  });
+
+  test('root config has no resolve_model_ids, but the active workstream config sets "omit" -> "" despite default runtime claude', () => {
+    const ws = 'ws-alpha';
+    projDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-2297-proj-ws-'));
+    fs.mkdirSync(path.join(projDir, '.planning'), { recursive: true });
+    // Root config exists but does NOT set resolve_model_ids at all.
+    fs.writeFileSync(
+      path.join(projDir, '.planning', 'config.json'),
+      JSON.stringify({ model_profile: 'balanced' }, null, 2)
+    );
+    // The active workstream's own config explicitly sets "omit".
+    const wsConfigDir = path.join(projDir, '.planning', 'workstreams', ws);
+    fs.mkdirSync(wsConfigDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(wsConfigDir, 'config.json'),
+      JSON.stringify({ resolve_model_ids: 'omit' }, null, 2)
+    );
+    process.env.GSD_WORKSTREAM = ws;
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-planner'), '');
+  });
+});
+
+// ─── Group C: explicit `true` still materializes full model ids (acceptance #5) ──
+describe('#2297: resolve_model_ids:true still materializes full Claude model ids', () => {
+  let projDir;
+  beforeEach(() => { isolateHome(); projDir = null; });
+  afterEach(() => { rmDir(projDir); restoreHome(); });
+
+  test('resolve_model_ids:true + balanced profile -> full materialized claude-opus-4-8 id', () => {
+    projDir = mkProjWithConfig({ resolve_model_ids: true, model_profile: 'balanced' });
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-planner'), 'claude-opus-4-8');
+  });
+});
+
+// ─── Group D: registry parity guard ─────────────────────────────────────────
+describe('#2297: capability-registry nativeModelAliases parity guard', () => {
+  test('exactly the runtimes with hostBehaviors.nativeModelAliases:true match RUNTIMES_WITH_NATIVE_ALIASES ([\'claude\'])', () => {
+    // The model-resolver hardcodes RUNTIMES_WITH_NATIVE_ALIASES = new Set(['claude'])
+    // rather than reading the registry at runtime. This test keeps that
+    // hardcoded set honest against the generated registry's actual contract:
+    // registry.runtimes[id].runtime.hostBehaviors.nativeModelAliases.
+    // If a future runtime gains nativeModelAliases:true, this fails loudly so
+    // RUNTIMES_WITH_NATIVE_ALIASES in model-resolver.cts is updated in lockstep.
+    const registry = require('../gsd-core/bin/lib/capability-registry.cjs');
+
+    const nativeAliasRuntimes = Object.keys(registry.runtimes)
+      .filter((id) => registry.runtimes[id]?.runtime?.hostBehaviors?.nativeModelAliases === true)
+      .sort();
+
+    assert.deepStrictEqual(nativeAliasRuntimes, ['claude']);
+  });
+});
+
+// ─── Group E: installer writes the per-install .gsd-runtime marker ─────────
+describe('#2297: installer emits the gsd-core/.gsd-runtime marker (fixture parity)', () => {
+  test('claude and codex install-tree fixtures both list gsd-core/.gsd-runtime', () => {
+    // These fixtures are flat JSON arrays of install-relative paths, generated
+    // by running the real installer (tests/fixtures/install-tree/*.json). Their
+    // presence here proves the installer actually emits the per-install marker
+    // that resolveActiveRuntime()'s precedence chain falls back to.
+    const claudeFixturePath = path.join(__dirname, 'fixtures', 'install-tree', 'claude.json');
+    const codexFixturePath = path.join(__dirname, 'fixtures', 'install-tree', 'codex.json');
+
+    const claudeFixture = JSON.parse(fs.readFileSync(claudeFixturePath, 'utf8'));
+    const codexFixture = JSON.parse(fs.readFileSync(codexFixturePath, 'utf8'));
+
+    assert.ok(Array.isArray(claudeFixture), 'expected claude.json fixture to be a flat array of paths');
+    assert.ok(Array.isArray(codexFixture), 'expected codex.json fixture to be a flat array of paths');
+
+    assert.ok(
+      claudeFixture.includes('gsd-core/.gsd-runtime'),
+      'expected claude.json install-tree fixture to include gsd-core/.gsd-runtime'
+    );
+    assert.ok(
+      codexFixture.includes('gsd-core/.gsd-runtime'),
+      'expected codex.json install-tree fixture to include gsd-core/.gsd-runtime'
+    );
+  });
+});
+
+// ─── Group F: the install-marker precedence rung, driven directly (#2297) ──
+// Previously untested: with no GSD_RUNTIME and no project config.runtime, the
+// active runtime falls all the way through to the per-install .gsd-runtime
+// marker (third precedence rung). The dev/source tree has no real marker file,
+// so these tests drive that rung directly via the _setInstallRuntimeMarkerForTests
+// / _resetInstallRuntimeMarkerCacheForTests seams exported specifically for this
+// purpose (#2297 correctness-review gap).
+describe('#2297: install-marker precedence rung (GSD_RUNTIME and config.runtime both absent)', () => {
+  let projDir;
+  beforeEach(() => {
+    isolateHome(); // also deletes GSD_RUNTIME
+    projDir = null;
+    // Belt-and-suspenders: the marker rung is only reached when GSD_RUNTIME and
+    // config.runtime are both absent; isolateHome() already deletes GSD_RUNTIME.
+    delete process.env.GSD_RUNTIME;
+  });
+  afterEach(() => {
+    rmDir(projDir);
+    restoreHome();
+    // CRITICAL: reset the module-level marker cache after every case in this
+    // block so a set value never leaks into a later case here, or into any
+    // OTHER describe block in this file (readInstallRuntimeMarker() otherwise
+    // memoizes the first value it sees for the lifetime of the process).
+    _resetInstallRuntimeMarkerCacheForTests();
+  });
+
+  test('marker="codex" (non-alias runtime): honors the poisoned global omit -> ""', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    _setInstallRuntimeMarkerForTests('codex');
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), '');
+  });
+
+  test('marker="claude": ignores the poisoned global omit -> "sonnet"', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    _setInstallRuntimeMarkerForTests('claude');
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), 'sonnet');
+  });
+
+  test('marker="claude-code" (alias): canonicalized to "claude" and still ignores the poisoned global omit -> "sonnet"', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    _setInstallRuntimeMarkerForTests('claude-code');
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), 'sonnet');
+  });
+
+  test('marker unset (null): falls through to the "claude" default and ignores the poisoned global omit -> "sonnet"', () => {
+    writeGlobalDefaults({ resolve_model_ids: 'omit' });
+    projDir = mkProjNoPlanning();
+    _setInstallRuntimeMarkerForTests(null);
+
+    assert.strictEqual(resolveModelInternal(projDir, 'gsd-executor'), 'sonnet');
+  });
+});
diff --git a/tests/fixtures/golden-install-parity/antigravity.json b/tests/fixtures/golden-install-parity/antigravity.json
index 9d437f1b6..f2794785a 100644
--- a/tests/fixtures/golden-install-parity/antigravity.json
+++ b/tests/fixtures/golden-install-parity/antigravity.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md": "5f86de1decbd16d2",
   "agents/gsd-user-profiler.md": "25d65f6458454764",
   "agents/gsd-verifier.md": "224e8df2d8fd1d95",
+  "gsd-core/.gsd-runtime": "54e851f5dd76ba94",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "ea841e2865248e74",
diff --git a/tests/fixtures/golden-install-parity/augment.json b/tests/fixtures/golden-install-parity/augment.json
index fb72f7679..518579938 100644
--- a/tests/fixtures/golden-install-parity/augment.json
+++ b/tests/fixtures/golden-install-parity/augment.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md": "1cb62ea69b117acb",
   "commands/gsd-workspace.md": "dd1bc09d2b768e0b",
   "commands/gsd-workstreams.md": "52ab9c585d3a00f3",
+  "gsd-core/.gsd-runtime": "ba737a9959aad238",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/claude-local.json b/tests/fixtures/golden-install-parity/claude-local.json
index e38d67e4e..f275ccd65 100644
--- a/tests/fixtures/golden-install-parity/claude-local.json
+++ b/tests/fixtures/golden-install-parity/claude-local.json
@@ -105,6 +105,7 @@
   "commands/gsd-verify-work.md": "246ac304c4dfde48",
   "commands/gsd-workspace.md": "5928e93b8ab475ac",
   "commands/gsd-workstreams.md": "52ab9c585d3a00f3",
+  "gsd-core/.gsd-runtime": "98038b25280788a4",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/claude.json b/tests/fixtures/golden-install-parity/claude.json
index 9c3e777ca..191d27c58 100644
--- a/tests/fixtures/golden-install-parity/claude.json
+++ b/tests/fixtures/golden-install-parity/claude.json
@@ -34,6 +34,7 @@
   "agents/gsd-ui-researcher.md": "9e3ac030767167e0",
   "agents/gsd-user-profiler.md": "003276f85792cfda",
   "agents/gsd-verifier.md": "2271174b5aa20e31",
+  "gsd-core/.gsd-runtime": "98038b25280788a4",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/cline.json b/tests/fixtures/golden-install-parity/cline.json
index 3ae2ffca5..76b57bc6c 100644
--- a/tests/fixtures/golden-install-parity/cline.json
+++ b/tests/fixtures/golden-install-parity/cline.json
@@ -38,6 +38,7 @@
   "agents/gsd-ui-researcher.md": "1bb303f3a3c4dfc9",
   "agents/gsd-user-profiler.md": "622220df0654b6bf",
   "agents/gsd-verifier.md": "75912e9cadd83eb3",
+  "gsd-core/.gsd-runtime": "98d4891544955482",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "476aa24e8c4f03cf",
diff --git a/tests/fixtures/golden-install-parity/codebuddy.json b/tests/fixtures/golden-install-parity/codebuddy.json
index be00b5ba3..ea9b0e9fd 100644
--- a/tests/fixtures/golden-install-parity/codebuddy.json
+++ b/tests/fixtures/golden-install-parity/codebuddy.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md": "6edbbb82a1f2aea7",
   "commands/gsd-workspace.md": "d765ff60cde657a6",
   "commands/gsd-workstreams.md": "884b6c8d648422c7",
+  "gsd-core/.gsd-runtime": "04e9f0f6433d6d58",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/codex.json b/tests/fixtures/golden-install-parity/codex.json
index 2283faaf7..fa2feb266 100644
--- a/tests/fixtures/golden-install-parity/codex.json
+++ b/tests/fixtures/golden-install-parity/codex.json
@@ -141,6 +141,7 @@
   "agents/gsd-verifier.md": "4ac4b860e2504374",
   "agents/gsd-verifier.toml": "8ed9fb961409e894",
   "config.toml": "b5f627b42f060910",
+  "gsd-core/.gsd-runtime": "243b0dc9b847e66c",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/copilot.json b/tests/fixtures/golden-install-parity/copilot.json
index 6b55d69de..0fea999d6 100644
--- a/tests/fixtures/golden-install-parity/copilot.json
+++ b/tests/fixtures/golden-install-parity/copilot.json
@@ -36,6 +36,7 @@
   "agents/gsd-user-profiler.agent.md": "ae16a248e18dd42b",
   "agents/gsd-verifier.agent.md": "87a8e3238e838a39",
   "copilot-instructions.md": "1fb04111759f1645",
+  "gsd-core/.gsd-runtime": "d0bcfb0a7f01f8c9",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "ea841e2865248e74",
diff --git a/tests/fixtures/golden-install-parity/cursor.json b/tests/fixtures/golden-install-parity/cursor.json
index c325b7048..ce2d2bafe 100644
--- a/tests/fixtures/golden-install-parity/cursor.json
+++ b/tests/fixtures/golden-install-parity/cursor.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md": "86a42f859bc26dd6",
   "commands/gsd-workspace.md": "5c40114e6af87e3d",
   "commands/gsd-workstreams.md": "112660ceb663c750",
+  "gsd-core/.gsd-runtime": "0e49decc490cf91d",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "2525f1ae8b086828",
diff --git a/tests/fixtures/golden-install-parity/hermes.json b/tests/fixtures/golden-install-parity/hermes.json
index bfb688fae..6ecc73d01 100644
--- a/tests/fixtures/golden-install-parity/hermes.json
+++ b/tests/fixtures/golden-install-parity/hermes.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md": "8799b6013e06ae49",
   "agents/gsd-user-profiler.md": "ca3bf75581f211a0",
   "agents/gsd-verifier.md": "82d3e9015ed04017",
+  "gsd-core/.gsd-runtime": "d53ba9ce30ffd743",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "3a3409215044af9f",
diff --git a/tests/fixtures/golden-install-parity/kilo.json b/tests/fixtures/golden-install-parity/kilo.json
index f6cf859d8..4718f00c2 100644
--- a/tests/fixtures/golden-install-parity/kilo.json
+++ b/tests/fixtures/golden-install-parity/kilo.json
@@ -106,6 +106,7 @@
   "command/gsd-verify-work.md": "d07409c940a6ff00",
   "command/gsd-workspace.md": "9048133312f47fdc",
   "command/gsd-workstreams.md": "5e57eed1881c3891",
+  "gsd-core/.gsd-runtime": "687db6a1b110b149",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/kimi.json b/tests/fixtures/golden-install-parity/kimi.json
index b6bfa0e76..33062fbf3 100644
--- a/tests/fixtures/golden-install-parity/kimi.json
+++ b/tests/fixtures/golden-install-parity/kimi.json
@@ -99,6 +99,7 @@
   "agents/subagents/gsd-user-profiler.yaml": "645826a29d079159",
   "agents/subagents/gsd-verifier.md": "699f62763424ac68",
   "agents/subagents/gsd-verifier.yaml": "2d2bd6b37626f382",
+  "gsd-core/.gsd-runtime": "cb556f5d5cee2779",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/opencode.json b/tests/fixtures/golden-install-parity/opencode.json
index 18c8e6ac7..def43406a 100644
--- a/tests/fixtures/golden-install-parity/opencode.json
+++ b/tests/fixtures/golden-install-parity/opencode.json
@@ -106,6 +106,7 @@
   "command/gsd-verify-work.md": "f23fff8e6d71f704",
   "command/gsd-workspace.md": "1e581bdb33bc8f55",
   "command/gsd-workstreams.md": "5e57eed1881c3891",
+  "gsd-core/.gsd-runtime": "0d74cc0a7af2a416",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/pi.json b/tests/fixtures/golden-install-parity/pi.json
index 5d466b6d3..f6f5f6a24 100644
--- a/tests/fixtures/golden-install-parity/pi.json
+++ b/tests/fixtures/golden-install-parity/pi.json
@@ -2,6 +2,7 @@
   ".gsd-profile": "0e716a5fef4e6dc1",
   ".gsd/defaults.json": "560664b045e645cb",
   "extensions/gsd.cjs": "619cec0af9cfdadf",
+  "gsd-core/.gsd-runtime": "94e95f0bb38f8e0f",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/golden-install-parity/qwen.json b/tests/fixtures/golden-install-parity/qwen.json
index bc9d18d04..7442dbc44 100644
--- a/tests/fixtures/golden-install-parity/qwen.json
+++ b/tests/fixtures/golden-install-parity/qwen.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md": "e3768304c1c77753",
   "agents/gsd-user-profiler.md": "13388a80dc302a66",
   "agents/gsd-verifier.md": "113d8dcff860b595",
+  "gsd-core/.gsd-runtime": "2b626670f713516a",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "6e98d76e955e35a2",
diff --git a/tests/fixtures/golden-install-parity/trae.json b/tests/fixtures/golden-install-parity/trae.json
index 03ebaca70..b8df3cf02 100644
--- a/tests/fixtures/golden-install-parity/trae.json
+++ b/tests/fixtures/golden-install-parity/trae.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md": "9e1a84a55a4cac99",
   "agents/gsd-user-profiler.md": "622220df0654b6bf",
   "agents/gsd-verifier.md": "99e95e235aacffbf",
+  "gsd-core/.gsd-runtime": "c96852d55ce78a68",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "de4627dff103d527",
diff --git a/tests/fixtures/golden-install-parity/windsurf.json b/tests/fixtures/golden-install-parity/windsurf.json
index 6e44a10e3..cd049cdc3 100644
--- a/tests/fixtures/golden-install-parity/windsurf.json
+++ b/tests/fixtures/golden-install-parity/windsurf.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md": "c348aa3ff8412ecb",
   "agents/gsd-user-profiler.md": "622220df0654b6bf",
   "agents/gsd-verifier.md": "a07b00b9c5b7b338",
+  "gsd-core/.gsd-runtime": "fe100af8906532d6",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "5636ca0b726871b2",
diff --git a/tests/fixtures/golden-install-parity/zcode.json b/tests/fixtures/golden-install-parity/zcode.json
index 36c85cee3..4b6b848b1 100644
--- a/tests/fixtures/golden-install-parity/zcode.json
+++ b/tests/fixtures/golden-install-parity/zcode.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md": "71aad09ecfd3f844",
   "commands/gsd-workspace.md": "611002e4941d5654",
   "commands/gsd-workstreams.md": "57a8ef0af8c085d7",
+  "gsd-core/.gsd-runtime": "d0f601b915afd6bf",
   "gsd-core/VERSION": "ef0deccd81a6723c",
   "gsd-core/bin/check-latest-version.cjs": "e4a224058c8f4d74",
   "gsd-core/bin/ensure-runtime-build.cjs": "51bc64467ab30f62",
diff --git a/tests/fixtures/install-tree/antigravity.json b/tests/fixtures/install-tree/antigravity.json
index 129debac2..3c57eb48e 100644
--- a/tests/fixtures/install-tree/antigravity.json
+++ b/tests/fixtures/install-tree/antigravity.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/augment.json b/tests/fixtures/install-tree/augment.json
index 1c5977a7c..8aa824a21 100644
--- a/tests/fixtures/install-tree/augment.json
+++ b/tests/fixtures/install-tree/augment.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md",
   "commands/gsd-workspace.md",
   "commands/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/claude-local.json b/tests/fixtures/install-tree/claude-local.json
index 46d4776ea..03c23b7b2 100644
--- a/tests/fixtures/install-tree/claude-local.json
+++ b/tests/fixtures/install-tree/claude-local.json
@@ -105,6 +105,7 @@
   "commands/gsd-verify-work.md",
   "commands/gsd-workspace.md",
   "commands/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/claude.json b/tests/fixtures/install-tree/claude.json
index 656bf934b..5e75abf38 100644
--- a/tests/fixtures/install-tree/claude.json
+++ b/tests/fixtures/install-tree/claude.json
@@ -34,6 +34,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/cline.json b/tests/fixtures/install-tree/cline.json
index 668e59098..cc3b39e3b 100644
--- a/tests/fixtures/install-tree/cline.json
+++ b/tests/fixtures/install-tree/cline.json
@@ -38,6 +38,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/codebuddy.json b/tests/fixtures/install-tree/codebuddy.json
index dcc5e54bc..1b9122fe1 100644
--- a/tests/fixtures/install-tree/codebuddy.json
+++ b/tests/fixtures/install-tree/codebuddy.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md",
   "commands/gsd-workspace.md",
   "commands/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/codex.json b/tests/fixtures/install-tree/codex.json
index a5db2f467..38f06021b 100644
--- a/tests/fixtures/install-tree/codex.json
+++ b/tests/fixtures/install-tree/codex.json
@@ -141,6 +141,7 @@
   "agents/gsd-verifier.md",
   "agents/gsd-verifier.toml",
   "config.toml",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/copilot.json b/tests/fixtures/install-tree/copilot.json
index bf257edbf..1f091658e 100644
--- a/tests/fixtures/install-tree/copilot.json
+++ b/tests/fixtures/install-tree/copilot.json
@@ -36,6 +36,7 @@
   "agents/gsd-user-profiler.agent.md",
   "agents/gsd-verifier.agent.md",
   "copilot-instructions.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/cursor.json b/tests/fixtures/install-tree/cursor.json
index 373692429..ab33184c9 100644
--- a/tests/fixtures/install-tree/cursor.json
+++ b/tests/fixtures/install-tree/cursor.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md",
   "commands/gsd-workspace.md",
   "commands/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/hermes.json b/tests/fixtures/install-tree/hermes.json
index cb82f8eb8..3e24cc634 100644
--- a/tests/fixtures/install-tree/hermes.json
+++ b/tests/fixtures/install-tree/hermes.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/kilo.json b/tests/fixtures/install-tree/kilo.json
index 93ff07f73..13fd26098 100644
--- a/tests/fixtures/install-tree/kilo.json
+++ b/tests/fixtures/install-tree/kilo.json
@@ -106,6 +106,7 @@
   "command/gsd-verify-work.md",
   "command/gsd-workspace.md",
   "command/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/kimi.json b/tests/fixtures/install-tree/kimi.json
index 03d9428da..e2cd1609b 100644
--- a/tests/fixtures/install-tree/kimi.json
+++ b/tests/fixtures/install-tree/kimi.json
@@ -99,6 +99,7 @@
   "agents/subagents/gsd-user-profiler.yaml",
   "agents/subagents/gsd-verifier.md",
   "agents/subagents/gsd-verifier.yaml",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/opencode.json b/tests/fixtures/install-tree/opencode.json
index 0ac467bf3..bceedbaae 100644
--- a/tests/fixtures/install-tree/opencode.json
+++ b/tests/fixtures/install-tree/opencode.json
@@ -106,6 +106,7 @@
   "command/gsd-verify-work.md",
   "command/gsd-workspace.md",
   "command/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/pi.json b/tests/fixtures/install-tree/pi.json
index 31f35703b..de7490c51 100644
--- a/tests/fixtures/install-tree/pi.json
+++ b/tests/fixtures/install-tree/pi.json
@@ -2,6 +2,7 @@
   ".gsd-profile",
   ".gsd/defaults.json",
   "extensions/gsd.cjs",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/qwen.json b/tests/fixtures/install-tree/qwen.json
index d1d1e8dc9..c6b6456b0 100644
--- a/tests/fixtures/install-tree/qwen.json
+++ b/tests/fixtures/install-tree/qwen.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/trae.json b/tests/fixtures/install-tree/trae.json
index 401b9fa55..786427c7c 100644
--- a/tests/fixtures/install-tree/trae.json
+++ b/tests/fixtures/install-tree/trae.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/windsurf.json b/tests/fixtures/install-tree/windsurf.json
index eca97635e..7451e92e1 100644
--- a/tests/fixtures/install-tree/windsurf.json
+++ b/tests/fixtures/install-tree/windsurf.json
@@ -35,6 +35,7 @@
   "agents/gsd-ui-researcher.md",
   "agents/gsd-user-profiler.md",
   "agents/gsd-verifier.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",
diff --git a/tests/fixtures/install-tree/zcode.json b/tests/fixtures/install-tree/zcode.json
index fc10b6b55..ea0653367 100644
--- a/tests/fixtures/install-tree/zcode.json
+++ b/tests/fixtures/install-tree/zcode.json
@@ -106,6 +106,7 @@
   "commands/gsd-verify-work.md",
   "commands/gsd-workspace.md",
   "commands/gsd-workstreams.md",
+  "gsd-core/.gsd-runtime",
   "gsd-core/VERSION",
   "gsd-core/bin/check-latest-version.cjs",
   "gsd-core/bin/ensure-runtime-build.cjs",