feat(#2093): migrate Kilo onto EoS imperative adapter + hook-bus/model/MCP/dispatch upgrades (ADR-1239)

Fold remaining isKilo logic branches into descriptor-driven reads:
finishPermissionWriter (uninstall cleanup), skipSharedHooksInstall (hooks
copy), and a skills converter-name registry (the artifactLayout.converter
field is now load-bearing, not decorative). frontmatterDialect stays the
documented dispatch key for frontmatter (no descriptor field for it). Dead
isKilo destructure bindings removed. Byte-identical golden parity for all 16
runtimes (opencode, which shares kilo's combined-family path, verified clean).

UPGRADE 1 (hook bus): install .kilo/plugins/gsd-core.js native plugin +
extensionEvents:"kilo" + EXTENSION_EVENT_SURFACES.kilo (OpenCode-fork bus).
UPGRADE 2 (active model): populate runtimeTierDefaults.kilo + thread
modelOverride through convertClaudeToKiloFrontmatter — model no longer stripped
from agents. UPGRADE 3 (MCP): document the gsd-core MCP companion under kilo's
mcp config key. UPGRADE 4 (named dispatch): agents/*.md mode:subagent roster is
the Task-tool dispatch surface (tested); subagentToolkit stays 'undocumented'
per AC so dispatch degrades to 'degraded' by design.

Model-catalog single-source edit ripples the shared model-catalog.json hash
into all 16 golden fixtures (expected). Inline defect fixes (no-defer): stale-
bake-guard resolveAgentDir 'agent'->'agents' (was a silent no-op for opencode/
codex), hardcoded 'Removed OpenCode plugin' uninstall log -> generic, and the
connect-gsd-mcp-server.md OpenCode mcpServers->mcp doc error.

Tests: kilo-imperative-reference (adapter/axes/fail-closed/degradation/
hostBehaviors + widened isKilo source-grep across 4 modules) + kilo-upgrades
(plugin parity+load, model-override converter, agents dispatch surface, MCP
doc). Matrix + how-to + config docs updated; changeset added.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/runtime-artifact-conversion.cts

@@ -1676,7 +1676,12 @@ function convertClaudeToOpencodeFrontmatter(content, { isAgent = false, modelOve
 }
 
 // Kilo CLI — same conversion logic as OpenCode, different config paths.
-function convertClaudeToKiloFrontmatter(content, { isAgent = false } = {}) {
+// DEFECT.GENERATIVE-FIX: this body is mirrored in bin/install.js's
+// convertClaudeToKiloFrontmatter (used by bin/install.js's own legacy install
+// path). Neither copy re-exports the other — mirror any behavior change into
+// both. Guarded by the output-parity test in tests/runtime-converters.test.cjs
+// (#2093).
+function convertClaudeToKiloFrontmatter(content, { isAgent = false, modelOverride = null } = {}) {
   // Replace tool name references in content (applies to all files)
   let convertedContent = content;
   convertedContent = convertedContent.replace(/\bAskUserQuestion\b/g, 'question');
@@ -1835,6 +1840,14 @@ function convertClaudeToKiloFrontmatter(content, { isAgent = false } = {}) {
   // For agents: add required Kilo agent fields
   if (isAgent) {
     newLines.push('mode: subagent');
+    // Embed model override from ~/.gsd/defaults.json so model_overrides is
+    // respected on Kilo (which uses static agent frontmatter, not inline
+    // Task() model parameters) — mirrors convertClaudeToOpencodeFrontmatter's
+    // model emission exactly (#2093 UPGRADE 2 / ADR-1239; Kilo is an OpenCode
+    // fork with the same static-frontmatter model constraint). See #2256.
+    if (modelOverride) {
+      newLines.push(['model:', modelOverride].join(' '));
+    }
     newLines.push(...buildKiloAgentPermissionBlock(agentTools));
   }