refactor(hosts): defineHost() factory — 10 copy-paste host files become declarations

hosts/*.ts were ten copies of one file: runtimeRoot byte-identical in 9/10,
pathRewrites mechanically derivable from the host name for 7/10, the 11-entry
toolRewrites map byte-identical between openclaw and gbrain, and every asset
change a 10-file edit (cursor and slate had already fallen out of three other
hand-maintained lists). defineHost() owns the defaults; each host file now
declares only what makes it different (slate/cursor: 8 lines each). Shared
constants: CROSS_MODEL_RESOLVERS, GBRAIN_RESOLVERS, EXEC_STYLE_TOOL_REWRITES.
Genuinely-different things stayed explicit: codex/factory $GSTACK_ROOT
rewrites, hermes's tool vocabulary, claude's denylist+prefixable install,
opencode's wider runtimeRoot.

Proof: JSON.stringify(ALL_HOST_CONFIGS) dump-diff before/after EMPTY (and a
runtime walk confirmed no function-valued or undefined-keyed fields, so the
JSON diff is complete); gen:skill-docs --host all zero-diff; host-config +
gen-skill-docs + idempotency suites 485/485. Host files 595 -> 285 lines.
docs/ADDING_A_HOST.md teaches the factory pattern.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hosts/gbrain.ts

@@ -1,20 +1,13 @@
-import type { HostConfig } from '../scripts/host-config';
+import { defineHost, CROSS_MODEL_RESOLVERS, EXEC_STYLE_TOOL_REWRITES } from './define-host';
 
 /**
  * GBrain host config.
  * Compatible with GBrain >= v0.10.0 (doctor --fast --json, search CLI, entity enrichment).
  * When updating, check INSTALL_FOR_AGENTS.md in the GBrain repo for breaking changes.
  */
-const gbrain: HostConfig = {
+const gbrain = defineHost({
   name: 'gbrain',
   displayName: 'GBrain',
-  cliCommand: 'gbrain',
-  cliAliases: [],
-
-  globalRoot: '.gbrain/skills/gstack',
-  localSkillRoot: '.gbrain/skills/gstack',
-  hostSubdir: '.gbrain',
-  usesEnvVars: true,
 
   frontmatter: {
     mode: 'allowlist',
@@ -28,51 +21,19 @@ const gbrain: HostConfig = {
     includeSkills: [],
   },
 
-  pathRewrites: [
-    { from: '~/.claude/skills/gstack', to: '~/.gbrain/skills/gstack' },
-    { from: '.claude/skills/gstack', to: '.gbrain/skills/gstack' },
-    { from: '.claude/skills', to: '.gbrain/skills' },
+  extraPathRewrites: [
     { from: 'CLAUDE.md', to: 'AGENTS.md' },
   ],
-  toolRewrites: {
-    'use the Bash tool': 'use the exec tool',
-    'use the Write tool': 'use the write tool',
-    'use the Read tool': 'use the read tool',
-    'use the Edit tool': 'use the edit tool',
-    'use the Agent tool': 'use sessions_spawn',
-    'use the Grep tool': 'search for',
-    'use the Glob tool': 'find files matching',
-    'the Bash tool': 'the exec tool',
-    'the Read tool': 'the read tool',
-    'the Write tool': 'the write tool',
-    'the Edit tool': 'the edit tool',
-  },
+  toolRewrites: { ...EXEC_STYLE_TOOL_REWRITES },
 
   // GBrain gets brain-aware resolvers. All other hosts suppress these.
   suppressedResolvers: [
-    'DESIGN_OUTSIDE_VOICES',
-    'ADVERSARIAL_STEP',
-    'CODEX_SECOND_OPINION',
-    'CODEX_PLAN_REVIEW',
-    'REVIEW_ARMY',
+    ...CROSS_MODEL_RESOLVERS,
     // NOTE: GBRAIN_CONTEXT_LOAD and GBRAIN_SAVE_RESULTS are NOT suppressed here.
     // GBrain is the only host that gets brain-first lookup and save-to-brain behavior.
   ],
 
-  runtimeRoot: {
-    globalSymlinks: ['bin', 'browse/dist', 'browse/bin', 'gstack-upgrade', 'ETHOS.md'],
-    globalFiles: {
-      'review': ['checklist.md', 'TODOS-format.md'],
-    },
-  },
-
-  install: {
-    prefixable: false,
-    linkingStrategy: 'symlink-generated',
-  },
-
   coAuthorTrailer: 'Co-Authored-By: GBrain Agent <agent@gbrain.dev>',
-  learningsMode: 'basic',
-};
+});
 
 export default gbrain;