fix(ri-050): forge fails closed without providers; explicit typed simulation (#1275) (#1278)

packages/forge/PLAN.md

@@ -539,3 +539,43 @@ Not every brief needs full Board of Directors review. The classification system
 ### Backward compatibility
 
 Existing briefs without a `class` field are auto-classified. The default (no matching keywords) is `strategic`, so all existing runs get the full pipeline unless keywords trigger `technical`.
+
+---
+
+## Fail-Closed Execution & Explicit Simulation (SDLC-D-035)
+
+**Added:** 2026-08-17
+
+Forge fails closed when a required capability is missing. It never runs a
+pipeline with a stub executor and reports success.
+
+### Normal mode (default)
+
+- No task executor wired → the CLI exits nonzero with the typed capability
+  error `FORGE_NO_EXECUTOR`. No run is created.
+- A stage whose gate is approval-based (board approval, planning approvals,
+  remediation re-review, discovery/analysis attestations) records a typed
+  `waiting-for-authority` stage result and raises `FORGE_AUTHORITY_REQUIRED`.
+  It never passes vacuously.
+- A stage whose gate requires an unwired provider (AI reviewer, CI pipeline)
+  records a typed `blocked` stage result and raises `FORGE_NO_REVIEWER` /
+  `FORGE_NO_CI_PIPELINE`. The synthetic echo-review approval in `06-review`
+  and all vacuous `true` gates were removed.
+
+### Explicit simulation (`--simulate`)
+
+Opts into stub/synthetic execution. Every stage result, every gate result, and
+the run manifest carry the distinct typed status `simulated` (manifest also
+records `mode: "simulated"`). `simulated` is a non-satisfying outcome:
+`isSatisfyingOutcome()` and all completion/gate consumers treat only `passed`
+as satisfying. The CLI exits 0 for a simulated run only because the caller
+explicitly passed `--simulate`, and prints a loud SIMULATED banner.
+
+### Typed outcome model
+
+Every gate/task outcome is one of the closed set
+`passed | failed | blocked | error | waiting-for-authority | simulated |
+not-applicable`, with the reason recorded on the stage status and each gate
+result in `manifest.json`. Missing implementations, missing gate evidence,
+unknown stages, process errors, and timeouts map to fail-closed members —
+never to `passed`.