fix(installer): fail closed on test enumeration errors

docs/scratchpads/1050-install-state-machine-red-fixture.md

@@ -52,6 +52,7 @@ Implement C1 from the canonical greenfield-install PRD v2: a transactional P0–
 - [x] Debian/glibc checkout fixture now packages the complete current checkout, verifies its digest in-container, and reaches the expected attributable RED without host inheritance. CI compares its exact final phase map/reasons to `tools/fixtures/greenfield-expected-red.tsv`; the fixture remains red while the detector job is green only on an exact match.
 - [ ] Reviews complete. Reviews 80 (`rev-security-02`) and 81 (`rev-974`) requested changes at `3934e03f`; their eight non-overlapping detector findings are being remediated red-first. Current remediation adds canonical-image portability, absolute P3 CLI propagation, exact expected-RED schema/cardinality, passwd-HOME binding, created-path owner/mode policy, real-action P2–P8 fault injection, verified non-empty remote installer execution, and seeded secret-canary/redacted diagnostics. Both old verdicts become void when the remediation head moves and require fresh independent review.
 - [x] Successor remediation for review 90 is RED-first and recorded in `docs/reports/verification/1050-successor-remediation/`: the manifest now binds the complete supported final P0 reason; P4 rejects an incomplete created-path walk instead of discarding `find` failure; and the TERM no-exit control is independent of filesystem enumeration order while retaining a proven RED mutation. Pipeline 2224's 32/2 result was a path-order-sensitive control, not evidence that the resume bug's premise became stale. The enumeration-class sweep additionally replaced order-dependent `find | head -1` source-root selection with a checked complete inventory requiring exactly one extracted root.
+- [x] C1 fix round for reviews 92/93: Blocker B was completed first. RED was reproduced before implementation: a planted `{"status":"in-progress"}` record makes the complete real walk fail the suite at P2, while the same planted defect beneath a target-owned mode-0100 directory makes real `find` fail and the frozen suite falsely exit 0 with `installer next lane tests passed`. One shared helper now captures and checks the complete NUL-delimited population before testing absence across the primary and copied harness sites; grep no-match is distinct from read failure. The same attack child drives the full suite RED with a named enumeration error, while ordinary native and root/container runs pass. Blocker A then regenerated the exact installer sidecar; provider-fetch validation remains the required post-push bar. Working estimate: 16K tokens; no external hard cap; 60% context is the stop/report gate.
 
 ## Risks / blockers
 
@@ -82,3 +83,6 @@ Implement C1 from the canonical greenfield-install PRD v2: a transactional P0–
 - Comparator controls pass for verdict drift, unexpected exit, manifest shrink, missing phases, duplicate rows, unknown cases, and unknown kinds. Verified-fetch controls pass for successful execution and failed/empty/digest-mismatch rejection.
 - `bash tools/e2e-install-test.sh --lane next --source checkout --git present` returns the required expected RED in clean Debian/glibc as uid 1001: installer P0/P1/P2/P3/P7 PASS; P4/P5/P6/P8 and P9 blocking; no `Done.` claim; checkout archive digest pinned and current framework installer exercised. `tools/verify-greenfield-expected-red.sh` converts that expected detector result into a green CI assertion and fails on any unreviewed verdict drift.
 - Earlier repository gates passed: `pnpm typecheck`, `pnpm lint`, `pnpm format:check`, upgrade manifest/rollback/durable-snapshot/migration suites, and focused `@mosaicstack/mosaic` tests with an isolated npm prefix. Full exact-remediation rerun is required before push.
+- Review-93 RED evidence at frozen `378bc1a`: isolated positive-control full-suite exit `1` with `P2 left an in-progress transaction`; isolated permission-failure attack full-suite exit `0` with final `installer next lane tests passed`. No binary shadowing or PATH interception was used; the failure came from a real target-owned mode-0100 directory.
+- Fix-round GREEN: `pnpm test:installer`, native next-lane, root/`ci-base:latest` next-lane, state-machine, verified-fetch, Bash syntax, ShellCheck, `pnpm typecheck`, `pnpm lint`, `pnpm format:check`, and `git diff --check` pass. The direct attack child exits 1 and names `P2 fault-state enumeration failed`. All 81 Mosaic Vitest files / 1508 tests pass under an isolated npm prefix; the wider framework-shell chain reaches the pre-existing #973 Bash-line-number gate and exits 97, matching the known host-specific condition rather than this delta. Codex code review approved at 0.93 confidence with zero findings; Codex security review reported no risk at 0.96 confidence with zero findings.
+- Sidecar GREEN locally: `sha256sum -c tools/install.sh.sha256` and the workflow's expected/actual comparison both resolve `e59cb441a2f37ae9150f8eae470238e9d858a1816df93343d9784a6796676096`. This is not substituted for the required immutable provider-fetch arm at the pushed head.