feat(#903): generate Loop Host Contract from workflow markers (ADR-857 phase 3a-impl-2) (#906)

Replace the inline LOOP_HOST_CONTRACT constant in the Capability Registry
generator with a generated-from-workflows contract (ADR-894 §3). The contract
is now derived from inert `<!-- gsd:loop-host ... -->` marker blocks in the five
step workflows, emitted as the committed gsd-core/bin/lib/loop-host-contract.cjs,
and required by gen-capability-registry.cjs — one source of truth, no drift.

Drift guards in gen-loop-host-contract.cjs: per-step point ownership (each step
must declare exactly its canonical loop points), multiple-block + duplicate-key
hard errors, and a word-boundary agent-role cross-check. Contract content is
byte-identical to the former constant; registry-only, nothing wired into the
live loop.

Closes #903

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

docs/ARCHITECTURE.md

@@ -369,6 +369,7 @@ Node.js CLI utility (`gsd-tools.cjs`) with domain modules split across `gsd-core
 | `schema-detect.cjs`    | Schema-drift detection for ORM patterns (Prisma, Drizzle, etc.)                                     |
 | `profile-pipeline.cjs` | User behavioral profiling data pipeline, session file scanning                                      |
 | `profile-output.cjs`       | Profile rendering, USER-PROFILE.md and dev-preferences.md generation                                |
+| `loop-host-contract.cjs`   | Generated Loop Host Contract — 12 loop points, per-step agent roles, and core artifacts; emitted by `scripts/gen-loop-host-contract.cjs` from workflow markers (ADR-894 §3); consumed by `gen-capability-registry.cjs` |
 | `capability-registry.cjs`  | Generated central Capability Registry — role-partitioned index of all co-located capability declarations; emitted by `scripts/gen-capability-registry.cjs` (ADR-894 §5) |
 
 

docs/INVENTORY-MANIFEST.json

@@ -1,5 +1,5 @@
 {
-  "generated": "2026-06-08",
+  "generated": "2026-06-09",
   "families": {
     "agents": [
       "gsd-advisor-researcher",
@@ -307,6 +307,7 @@
       "io.cjs",
       "learnings.cjs",
       "legacy-cleanup.cjs",
+      "loop-host-contract.cjs",
       "milestone.cjs",
       "model-catalog.cjs",
       "model-profiles.cjs",

docs/INVENTORY.md

@@ -370,7 +370,7 @@ The `gsd-planner` agent is decomposed into a core agent plus reference modules t
 
 ---
 
-## CLI Modules (98 shipped)
+## CLI Modules (99 shipped)
 
 Full listing: `gsd-core/bin/lib/*.cjs`.
 
@@ -418,6 +418,7 @@ Full listing: `gsd-core/bin/lib/*.cjs`.
 | `io.cjs` | CLI I/O primitives — `output`/`error` emission, JSON-error mode, and large-payload temp-file spillover (extracted from `core.cjs`, ADR-857) |
 | `learnings.cjs` | Cross-phase learnings extraction for `/gsd-extract-learnings` |
 | `legacy-cleanup.cjs` | Detect and remove leftover get-shit-done-cc artifacts; exports `planLegacyCleanup` (pure scan) and `applyLegacyCleanup` (thin IO applier) that root out stale files from the old package across every GSD-managed runtime config directory (#607) |
+| `loop-host-contract.cjs` | Generated Loop Host Contract — 12 loop points, per-step agent roles, and core artifacts for the five-step pipeline (discuss/plan/execute/verify/ship); emitted by `scripts/gen-loop-host-contract.cjs --write` (ADR-894 §3); consumed by `gen-capability-registry.cjs` |
 | `milestone.cjs` | Milestone archival, requirements marking |
 | `model-catalog.cjs` | CJS adapter over the shared model catalog JSON; exports canonical runtime tier defaults, agent profile maps, alias maps, and routing metadata for all CLI consumers |
 | `model-profiles.cjs` | Backward-compatible profile helpers derived from `model-catalog.cjs`; no longer owns its own model table |