Complete Phase 18 operational hardening

docs/rewrite-notes.md

@@ -31,7 +31,7 @@ The Go rewrite is complete when both of the following are true:
 
 ## Current implementation status
 
-The Go rewrite is currently in a deterministic foundation stage.
+The Go rewrite now has feature-complete runtime behavior for the module pipeline plus Phase 18 operational hardening coverage.
 
 Implemented:
 - CLI command surface for `audita process`.
@@ -97,9 +97,8 @@ Implemented:
   - validation override behavior when validation fields are set.
 - Generic JSON diagnostics primitives for LLM interactions (request metadata, request payload, response payload, optional error payload) with secret redaction.
 
-Not yet implemented in runtime pipeline:
-- Operational hardening beyond current Phase 16 runtime/reporting/diagnostics scope.
-- Rollout/Python retirement work.
+Not yet implemented:
+- Phase 19 rollout and Python retirement/documentation transition work.
 
 ## Completed phases
 
@@ -237,7 +236,7 @@ Not implemented in Phase 8 (by design):
 
 ## Remaining work plan
 
-Next recommended phase: **Phase 18 (operational hardening and subprocess integration)**.
+Next recommended phase: **Phase 19 (documentation, rollout, and Python retirement)**.
 
 ## Phase 9: Structured LLM client and scheduler infrastructure
 
@@ -628,6 +627,38 @@ The Go binary should be safe to call from other Go applications and should not r
 - Operational docs are accurate.
 - `go test ./...` passes.
 
+### Phase 18 completion status
+
+Completed.
+
+Implemented:
+- Expanded subprocess integration coverage in `cmd/audita/main_integration_test.go` for:
+  - successful default full-pipeline runs with `--output` and without `--output`;
+  - successful `--report-json` writes;
+  - large-transcript subprocess behavior;
+  - missing/unreadable transcript and missing/malformed glossary failures (portable handling where required);
+  - unwritable output and unwritable report-json failure behavior (portable handling where required);
+  - malformed structured LLM response failure behavior;
+  - synthetic backend LLM failure behavior;
+  - timeout/cancellation behavior with deterministic context cancellation hooks;
+  - mid-pipeline failure with partial module progress preserved in reports.
+- Hardened subprocess failure stderr output to include diagnostics path when available.
+- Added deterministic test-only subprocess LLM/runtime hooks used only in helper-process tests:
+  - backend failure mode;
+  - malformed structured-output mode;
+  - block-until-cancel mode;
+  - mid-pipeline fail mode.
+- Added regression coverage for secret redaction across subprocess stdout/stderr/report/diagnostics artifacts.
+- Confirmed existing LLM adapter and scheduler tests continue to cover:
+  - timeout and context cancellation propagation;
+  - retry behavior;
+  - malformed output safety;
+  - permit release on error/cancellation.
+- Added focused subprocess-caller operational guidance in `docs/subprocess-operations.md`.
+
+Intentionally deferred:
+- Phase 19 documentation/rollout/Python-retirement transitions.
+
 ## Phase 19: Documentation, rollout, and Python retirement
 
 ### Purpose