docs(sdk): document runtime bridge seam, strict mode, and fallback policy

docs/ARCHITECTURE.md

@@ -55,7 +55,7 @@ GSD is a **meta-prompting framework** that sits between the user and AI coding a
 ┌──────▼──────────────▼─────────────────▼──────────────┐
 │              CLI TOOLS LAYER                          │
 │   gsd-sdk query (sdk/src/query) + gsd-tools.cjs       │
-│   (State, config, phase, roadmap, verify, templates)  │
+│   SDK Runtime Bridge Module routes native vs fallback │
 └──────────────────────┬───────────────────────────────┘
                        │
 ┌──────────────────────▼───────────────────────────────┐
@@ -266,6 +266,17 @@ Runtime hooks that integrate with the host AI agent:
 
 See [`docs/INVENTORY.md`](INVENTORY.md#hooks-11-shipped) for the authoritative 11-hook roster.
 
+### SDK Runtime Bridge Module (`sdk/src/query-runtime-bridge.ts`)
+
+Programmatic SDK callers (`GSDTools`) route through one seam that owns query dispatch policy:
+
+- Native registry dispatch preference
+- Explicit subprocess fallback policy (`allowFallbackToSubprocess`)
+- Strict SDK mode (`strictSdk`) for fail-fast native-only enforcement
+- Structured dispatch observability (`onDispatchEvent`) with mode, reason, duration, and outcome
+
+This keeps callers thin adapters and centralizes transport decisions for SDK publishability.
+
 ### CLI Tools (`get-shit-done/bin/`)
 
 Node.js CLI utility (`gsd-tools.cjs`) with domain modules split across `get-shit-done/bin/lib/` (see [`docs/INVENTORY.md`](INVENTORY.md#cli-modules-33-shipped) for the authoritative roster):