test(tools/git): stop the fail-closed test escaping its sandbox; cover the API path

rev-974 (#1085 review 130) found three blockers. This closes the first two.

[1] SANDBOX ESCAPE. The test ran under `set -uo pipefail` with unchecked mkdir,
    calls-log redirect and `cd "$REPO_DIR"`, then prepended a possibly-nonexistent
    $MOCK_BIN to PATH -- while `git remote add origin` names the REAL repository.
    rev-974 forced setup failure with an unwritable AGENT_WORK_ROOT and the test
    continued past every error, ran `git init` in its CALLER's directory, added the
    real origin, and invoked its target:

        TARGET_REACHED args=-i 42 -c closing note

    With the committed target that is the real, provider-mutating issue-close.sh.
    ShellCheck flagged the unguarded cd as SC2164 independently.

    Now: `set -euo pipefail`, every setup step checked with a legible reason, and
    assert_mocked() proves BOTH `tea` and `curl` resolve inside $MOCK_BIN before any
    target invocation. Control: unwritable AGENT_WORK_ROOT -> rc=1 at mkdir, target
    never reached.

[2] THE API/no-login BRANCH HAD NO DISCRIMINATING COVERAGE. The mock always returned
    a tea login, so `gitea_issue_comment_api || fail-closed` was never executed.
    rev-974 replaced the whole fallback contract with an unconditional close --
    silently dropping the comment -- and the committed test still passed rc=0.

    Added three cases asserting the POSTCONDITION (which HTTP calls happened, in what
    order) rather than that a command ran: comment POST fails -> no PATCH and non-zero;
    comment succeeds -> strictly POST,PATCH; no comment requested -> PATCH only, never
    a POST. The curl mock now records method and URL. Control: replaying rev-974's
    contract destruction now fails with "API path: no comment POST attempted".

Two self-inflicted traps hit while adding `set -e`, both the same family as the #1086
defect be-coder-08 found, and both silent:
  - `grep -q X "$CALLS" && fail "..."` -- the ABSENT case (grep rc=1, the PASSING case
    for a must-not-appear assertion) is the last command of an && list and terminates
    the script with no message. All four converted to if-blocks.
  - `run_target ...; rc=$?` -- the function's non-zero RETURN trips set -e in the CALLER
    before rc is read; run_target's internal `set +e` protects the target, not the
    caller. All five call sites now `rc=0; run_target ... || rc=$?`.

Controls:
  unchanged main                  -> rc=1 "used 'tea issue comment'"
  fallback contract destroyed     -> rc=1 "API path: no comment POST attempted"
  unwritable AGENT_WORK_ROOT      -> rc=1 at setup, target never invoked
  fixed source                    -> rc=0

[3] remains open: with MOSAIC_GIT_IDENTITY=rev-974 the wrapper resolves
    GITEA_LOGIN_NAME=mosaicstack-mos, so one principal holds but the operation is
    attributed to Mos rather than the requested seat. That changes identity resolution
    shared by every wrapper in this directory and is not folded in here.

Reported-by: rev-974

.woodpecker/ci.yml

@@ -46,6 +46,10 @@ steps:
       # [0] of the pnpm chain, so severing that chain would silence it together
       # with everything it guards; this direct line keeps one instrument running.
       - bash packages/mosaic/framework/tools/quality/scripts/check-test-enumeration.sh
+      # Hermetic regression for issue-close.sh (#1081): mocks tea/curl onto PATH
+      # and sandboxes a throwaway git repo, so it resolves no real credentials and
+      # joins CI directly rather than the exclusions file.
+      - bash packages/mosaic/framework/tools/git/test-issue-close-fail-closed.sh
 
   # Blocking gate (#791): a framework upgrade must never write or delete an
   # operator-owned path. The HARD GATE proves an unanticipated operator sentinel

apps/gateway/src/federation/__tests__/enrollment.service.spec.ts

@@ -245,9 +245,21 @@ describe('EnrollmentService.createToken', () => {
     const after = Date.now();
 
     const expiresMs = new Date(result.expiresAt).getTime();
-    // Should be at most 900s from now
-    expect(expiresMs - before).toBeLessThanOrEqual(900_000 + 100);
+
+    // The property under test is CLAMPING: a 9999s request must come back as 900s.
+    // The gap between clamped and unclamped is 9_099_000 ms, so the tolerance below
+    // only has to exceed CI scheduling jitter — it does not need to be tight to keep
+    // the assertion discriminating. A 5s allowance consumes 0.05% of that margin and
+    // an unclamped result still misses by three orders of magnitude.
+    //
+    // It was 100ms and failed on a loaded agent at 900_106 — 6ms over (#1090). A
+    // wall-clock budget sized to a fast machine is a flake, not a tighter test.
+    const CI_JITTER_MS = 5_000;
+    expect(expiresMs - before).toBeLessThanOrEqual(900_000 + CI_JITTER_MS);
     expect(expiresMs - after).toBeGreaterThanOrEqual(0);
+    // Explicitly pin the clamp itself, independent of any timing allowance:
+    // unclamped (9999s) would exceed this by ~9_099_000 ms.
+    expect(expiresMs - before).toBeLessThan(1_000_000);
   });
 });
 

docs/scratchpads/1019-zero-timeout-harness.md

@@ -0,0 +1,71 @@
+# #1019 — Zero-timeout queue-guard harness race
+
+- **Issue:** #1019 (parent status remains `believed-fixed, pending jarvis validation`; do not close)
+- **Branch:** `fix/1019-ci-queue-timeout-harness`
+- **Owner:** `be-coder-08`
+- **Base:** `origin/main` at `5916aeefd6ed12bcac086c6834c7f6c4ae38e1bc`
+- **Charter:** `/home/hermes/agent-work/tl-mosaic/CHARTER-1019-HARNESS-FIX.md`
+
+## Objective
+
+Make `test-ci-queue-wait-tristate.sh` deterministic without changing any asserted outcome. Remove the indiscriminate zero-timeout race, require every status-classification case to prove the provider was observed, and prove the harness-controlled virtual clock is active.
+
+## Scope
+
+- In scope: `packages/mosaic/framework/tools/git/test-ci-queue-wait-tristate.sh` only, plus this evidence scratchpad.
+- Out of scope: guard parsers, D2/D3 behavior, installer/reseed staleness, PR #1060, and issue closure.
+
+## Acceptance criteria
+
+1. RED deterministically reproduces deadline pre-emption before the provider call.
+2. Every case that intends status classification positively proves provider observation.
+3. Pending observes `pending` before deterministic virtual-time expiration.
+4. The virtual clock has a positive interception control; a broken-clock mutant makes the suite red.
+5. The exact CI-base image passes the final harness repeatedly with zero failures.
+6. Baseline gates, independent code/security review, exact-head CI, and coordinator-authorized squash merge pass.
+
+## Plan
+
+1. Add deterministic RED instrumentation for the known merge/provider-unreachable pre-emption.
+2. Replace global `-t 0` with a nonzero timeout interpreted under an event-driven virtual clock; stub sleep without wall waiting.
+3. Add provider-observation and virtual-clock positive controls without changing outcome assertions.
+4. Run focused shell checks, repeat in exact CI-base image, baseline gates, and independent reviews.
+5. Commit with both identity layers, queue-guard plus direct Woodpecker terminal-state verification, push, self-post PR, verify poster/head/CI, obtain coordinator merge authorization, then squash merge without closing #1019.
+
+## Budget
+
+- No explicit token cap supplied. Keep scope to one harness file and one scratchpad; stop/report at the charter's 60% context gate.
+
+## Evidence
+
+- RED, deterministic pre-provider expiry: `evidence/1019-harness-fix/red-pre-provider-expiry.log` — rc 1; merge/provider-unreachable got rc 124 instead of 75, omitted CANNOT_ASSERT, did not observe the status provider, and wrote no additional audit record (four named failures).
+- GREEN host focused harness: `evidence/1019-harness-fix/green-host.log` — rc 0, all outcome classes passed.
+- Load-bearing clock negative control: a temporary same-directory mutant replaced the virtual `date` body with `/bin/date`; `evidence/1019-harness-fix/red-clock-not-intercepted.log` — rc 1 with named `virtual clock interception did not run` failures. The mutant file was removed after the run.
+- Exact CI-base repeat: `git.mosaicstack.dev/mosaicstack/stack/ci-base:latest`, repository mounted read-only, harness work under container `/tmp`; `evidence/1019-harness-fix/ci-image-repeat/summary.log` — **100 pass / 0 fail / 100 total**.
+- Synchronization design: provider-status observation creates the event marker; virtual time is 1000 before the event and 1002 afterward. Pending alone reaches the stubbed no-op sleep and a post-observation deadline check. `-t 1` is uniquely load-bearing because removing it restores the 900-second default deadline at virtual time 1900, which 1002 does not cross. The numeric timeout is subject semantics under virtual time, not a wall-clock synchronization duration.
+
+## Review remediation — semantic timeout vs. liveness bound
+
+Security review found that virtual time remained at 1000 forever before provider observation and stubbed sleep never waited. A regression looping before the status endpoint—or blocking in the first provider call—therefore could prevent `run_guard` from returning, so the post-return provider assertion could never fire.
+
+**General rule:** A timeout usually serves two purposes: semantics and liveness. Removing wall time from semantic synchronization can silently remove the only independent hang bound. Preserve deterministic virtual time for subject semantics, but provide a separately implemented real-clock liveness watchdog and prove that watchdog fires.
+
+Remediation:
+
+- Every guard subject invocation is launched by absolute `/usr/bin/python3` in a new session. Python's internal monotonic `wait(timeout=...)` provides real-clock liveness independently of PATH; expiry kills the entire isolated process group, so neither PATH-front shims nor a blocked provider descendant can retain the capture pipe.
+- Watchdog expiry returns distinct harness rc 90 plus `FAIL HANG watchdog`, separate from subject timeout rc 124.
+- A first attempt using absolute `/usr/bin/timeout -s KILL` passed on GNU coreutils but failed in the exact Alpine CI-base image: BusyBox killed the immediate wrapper while the guard/provider descendants survived and retained the command-substitution pipe. The process-group kill is therefore required behavior, not portability polish.
+- A committed positive control hangs the branch-provider stub before the status endpoint. It must terminate through the watchdog, emit the hang-specific diagnostic, return rc 90, and prove the status provider was never reached.
+- RED before remediation: a temporary ordinary-success mutant hung before provider observation; only an external control could kill the suite (rc 137), and there was no internal hang-specific diagnostic (`red-watchdog-absent.log`).
+- The watchdog mutant/control is load-bearing: removing the internal watchdog leaves the control unable to produce its required rc 90 and diagnostic.
+
+Post-review evidence:
+
+- Host focused harness with process-group watchdog: rc 0 (`green-watchdog-process-group-host.log`).
+- Exact Alpine CI-base focused harness with process-group watchdog: rc 0 (`green-watchdog-ci-image.log`).
+- Hanging ordinary-success mutant: suite rc 1; success returned rc 90, emitted `FAIL HANG watchdog`, and loudly reported that provider/clock observation did not occur (`red-watchdog-fires.log`).
+- Removed-`-t 1` mutant: suite rc 1; pending was terminated by the watchdog instead of producing `ASSERTED_NOT_READY`, proving the explicit timeout is load-bearing (`red-timeout-argument-removed.log`).
+
+## 60% context hold
+
+Stopped before baseline/review/commit as required by the charter. Remaining: inspect final diff, shell/static/baseline gates, independent code/security review, remediation if any, identity-bound commit/trailer verification, mandatory queue guard plus direct terminal Woodpecker `mosaic` enumeration, push, self-posted PR/provider poster read-back, exact-head terminal-green CI, coordinator merge authorization, squash merge, main CI verification, and leave #1019 unclosed as `believed-fixed, pending jarvis validation`.

docs/scratchpads/pr-merge-message-field.md

@@ -0,0 +1,99 @@
+# PR merge squash message field
+
+- **Charter:** `/home/hermes/agent-work/CHARTER-PRMERGE-MESSAGE-FIELD.md`
+- **Owner:** `be-coder-08`
+- **Branch:** `fix/pr-merge-message-field`
+- **Base:** remote `main` / local `origin/main` at `85d2108e4ed15c744ad3b87a5b629e7b2d39405a`
+- **Estate:** HOMELAB tooling shared by HOMELAB and USC
+
+## Objective
+
+Add an optional, identity-checked Gitea squash message to `pr-merge.sh` so genuine multi-author PRs retain non-poster branch authors without weakening hardcoded squash behavior.
+
+## Binding requirements
+
+1. `Do` remains hardcoded to `squash`; no provider/repository default may select merge style.
+2. A verified trailer uses a PR commit's linked `author.login` and that same commit's author email. No `/users/{login}` primary-email lookup occurs. Recorded rationale: this asks only what the provider can answer.
+3. A commit with `author.login` null blocks before merge, prints both the null provider fact and commit email fact, and names the escalation principal.
+4. The BLOCK arm must be observed firing; a normal canonical single-author API payload remains explicit squash plus its reviewed `head_commit_id`.
+5. Every provider mutation is read back from the provider; no real PR is merged during tests.
+
+## Derived interface decisions
+
+- Add `--co-author-trailers` rather than accepting arbitrary message text. The wrapper enumerates PR commits and constructs trailers, making an unchecked `Co-authored-by` line unexpressible.
+- Require `--escalate-to PRINCIPAL` with `--co-author-trailers`, so the BLOCK diagnostic always names a principal rather than a generic role.
+- Do not expose `MergeTitleField` separately. When trailers exist, set it from the provider PR title and set `MergeMessageField` only to construction-generated trailers. This preserves one provider source for the title and avoids an unrelated caller-controlled degree of freedom.
+- Preserve first-commit order and emit one trailer per distinct non-poster `author.login`, using that first linked commit's own email.
+
+## Canonical delivery plan
+
+1. Port the capability into the installed source of truth, `packages/mosaic/framework/tools/git/pr-merge.sh`; do not retain `infra/fleet/tools/git` as a second copy.
+2. Preserve canonical `--expect-head`, exact head branch/repository/SHA queue inspection, Gitea atomic head pinning, GitHub `--match-head-commit`, and delete-after-merge semantics.
+3. Do not port the deployed-only `--skip-queue-guard` bypass. Add the focused harness to the canonical framework-shell suite and re-establish RED/GREEN on the packaged baseline.
+4. Deliver through a reviewed package release followed by `mosaic update` with its default framework reseed. The installer snapshots, manifest-syncs framework-owned `tools/**`, and rolls back on failure.
+5. Before either estate relies on the change, require installed/package hash equality, `MergeMessageField` presence, and a green focused harness. Release/reseed ownership is currently unassigned and blocks activation after source merge.
+
+## Evidence
+
+- RED against the byte-identical deployed baseline (`sha256 08a65e8584c5…`): rc 1 with eight named failures. The wrapper rejected `--co-author-trailers`; the null-login path emitted none of the required BLOCK facts/principal; and both verified/ordinary API paths failed the stdin-config credential assertion (ordinary path exposed the fixture token through curl argv). Log: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-message-field-red.log`.
+- GREEN on the deployed-baseline candidate: verified linked multi-author payload, null-login BLOCK, required named principal, explicit squash, stdin-config token transport, and absence of `/users` lookup all passed. Log: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-message-field-green.log`.
+- RED against canonical packaged baseline `c581ef48…`: rc 1 with 32 assertions. It rejects the new option, and the first harness version did not satisfy canonical head branch/repository/SHA metadata. Log: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-packaged-baseline-red.log`. The port adapts the fixture rather than weakening canonical head controls.
+- Provider capability probe against `git.mosaicstack.dev`: authenticated `be-coder-08` POST to deliberately nonexistent PR `2147483647` with both message fields returned JSON HTTP 404; the unauthenticated same request returned JSON HTTP 401 (not the charter's predicted 403). The authenticated-vs-unauthenticated differential proves write authorization resolved while no mergeable subject existed. `tl-mosaic` ruled the literal non-load-bearing: preserve the observed 404/401 pair and do not manufacture a 403 case. No cause was inferred and no real PR was targeted.
+- Provider-generated trailer behavior is not treated as exclusive or absent. The wrapper's VERIFIED/BLOCK decision binds each requested non-poster trailer to commit `author.login` plus that commit's email; it does not assume `MergeMessageField` is the squash's only trailer source. The poster is omitted from the constructed list because the resulting squash author already records the poster; any additional provider-generated trailer is outside this change's unmeasured mechanism.
+- An early candidate SHA-256 `5de32876990e4f26920448cb3220cc7f1146d558b4dd2bc1ee1a2abee2f2cbe6` passed the initial harness, then author-side review found credential-fallback and argv-exposure defects. The live deployed wrapper was atomically restored to baseline SHA-256 `08a65e8584c52c6d41ea1c686f8b95585c21e4b37320a2447eba09359a0e02c1`; the remediated candidate remains only in the worktree.
+
+## Remediation and current review state
+
+1. Token and Basic Auth now use stdin curl configuration, not argv. PR title, contributor email, and the JSON payload also remain out of child argv.
+2. Each credential attempt binds commit inspection and merge. A token failure during either inspection or mutation causes Basic fallback to repeat inspection before mutation; the payload pins the inspected `head_commit_id`.
+3. Focused tests cover token-resolution fail-closed behavior, both HTTP-401 fallback seams, metadata/credential argv absence, null-login BLOCK, explicit squash, canonical reviewed-head binding, unchanged ordinary payload, and retained log-safe provider diagnostics. Token-resolution RED: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-token-resolution-red.log`.
+4. Codex review rounds 3–5 requested retained provider error text, log-safe provider diagnostics, fail-closed credential fallback, stable value-option parsing, and PR-title trailer-injection prevention. These are remediated with regression assertions. A post-remediation independent review is still required.
+5. **Accepted linkage limitation:** `author.login` resolution proves that the commit address maps to a registered provider account. It does not prove that the named principal authored the commit because Git author metadata is self-asserted. This gate checks attribution linkage, not authorship; commit signing is out of scope and currently unadopted. Coordinators explicitly ruled that this does not add a third state.
+6. Codex's sandbox could not execute the harness because its checkout was read-only; that environmental limitation is recorded separately from host-side test results.
+
+## Disposable provider fixture acceptance
+
+- Use a retained scratch repository only, with two branch authors and `author != committer` on at least one commit.
+- Arm A supplies a message-field trailer for one non-poster; record whether that value lands without forcing the partial-pair result into under-specified `APPENDS`/`REPLACES` labels. Demonstrate an absence control.
+- Arm B includes a registered trailer for a different non-poster on a branch commit; record whether it survives or drops. Verify identity through an existing commit whose `author.login` resolves and demonstrate an absence control.
+- Parse landed trailers key-agnostically with `^[A-Za-z-]+-[Bb]y:` and record generated poster pair presence/absence plus resulting poster attribution.
+- Record `/users/<login>` status and raw email only as non-gating estate telemetry. Never read `active`, `visibility`, or any profile field as an identity gate.
+- Use distinct principals: poster `be-coder-08`, merger `Mos`, Arm A `be-coder-07`, and Arm B `be-coder-06`. Capture every trailer-shaped line verbatim and in order. Zero trailer lines means the generator did not fire and the run is `VOID`, not evidence that either arm dropped.
+- Report the same read-back evidence to `mos-claude` on socket `default` and `tl-mosaic` on socket `mosaic-fleet`. Report values rather than mechanism inferences and stop on any poster-attribution regression.
+
+## Fixture preflight
+
+- Retained public repository: `mosaicstack/prmerge-trailer-fixture`; PR `#1`, posted by `be-coder-08` and reserved for merge by `Mos`.
+- Existing `mosaicstack/stack` commits resolve `be-coder-07` and `be-coder-06` through `author.login`; exact addresses are `[email protected]` and `[email protected]`.
+- Non-gating HOMELAB telemetry for authenticated reader `be-coder-08`: `/api/v1/users/be-coder-06` returned HTTP 200 with raw `email` value `[email protected]`.
+- Provider preflight showed PR commit enumeration is newest-first. A new RED test proved that deriving `head_commit_id` from the final array element selected the wrong commit. The candidate now reads `.head.sha` from the authenticated PR endpoint before enumeration, verifies it appears in the commit set, and atomically pins that SHA in the explicit squash payload. RED: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-head-order-red.log`.
+- Fixture PR head `f6ba6e5105031fa21f5ff7bd8e4379d99c16e1de` has `author.login=be-coder-07`, `committer.login=be-coder-08`, and branch-message trailer `Co-authored-by: be-coder-06 <[email protected]>`.
+
+## Fixture result
+
+- `Mos` merged retained fixture PR `#1` through staged candidate SHA-256 `60e779a85fd13b729d859ea7c986d1e9b1641b97991611329226c1b3113ffb6e`; resulting squash commit: `3f550715d9bc716426fd355a65fe997b3a90fa7d` with one parent.
+- Provider read-back: poster/commit author `be-coder-08`, committer/merger `Mos`. The run is non-void.
+- Trailer-shaped lines, verbatim and in order:
+  1. `Co-authored-by: be-coder-07 <[email protected]>`
+  2. `Co-authored-by: be-coder-08 <[email protected]>`
+- Arm A supplied field value (`be-coder-07`) landed. Arm B branch trailer (`be-coder-06`) dropped. Both fabricated absence controls remained absent. No `Co-committed-by:` line landed.
+- The candidate payload construction explicitly excludes the poster and supplied only the Arm A `be-coder-07` line. Therefore the landed poster line was provider-generated, not candidate-composed. The raw result supports `FIELD LANDS`, `BRANCH DROPS`, and `POSTER GENERATED`; it does not support a claim that candidate code supplied the poster. Evidence: `/home/hermes/agent-work/be-coder-08/evidence/prmerge-fixture-readback.log` and the retained provider object.
+- Retained fixture PR `#2` measured the N=2 shape needed by `#1030`: supplied `be-coder-07` then `be-coder-06`; both landed in that order, followed by the provider-generated poster line. No truncation or dedup occurred at N=2. Resulting squash: `39db9d13aed0…`.
+
+## Current hold point
+
+PR `mosaicstack/stack#1066` is open. Its first frozen head `f4b162fa…` was terminal-green in Woodpecker `mosaic` pipeline `#2225`, but that evidence becomes stale when the canonical port moves the head. The deployed wrapper remains baseline `08a65e85…`; no manual copy will occur. Canonical port tests, commit amendment, rebase, one guarded force-with-lease, exact-head CI, and new independent review remain. Even after source merge, activation remains blocked on an assigned package-release/reseed owner and installed-byte read-back.
+
+## Security review 96 remediation
+
+Exact reviewed predecessor head: `1ceb11058f64dd7f4a817ceb2124f980a1c4dd23`.
+
+RED-first focused harness produced 10 named failures: all curl calls lacked size/time/connect bounds; raw ESC email reached mutation; oversized and stalled curl failures were discarded and reached mutation; nonempty Basic output with resolver rc 91 authorized mutation.
+
+Security remediation:
+
+- Removed the cross-principal HTTP-401 Basic fallback. Both inspection-401 and merge-401 paths now refuse without Basic resolution or mutation; `get_gitea_basic_auth` references in the merge subject are 0.
+- Applied `--max-filesize`, `--max-time`, and `--connect-timeout` to all 3/3 provider curl sites and fail closed on curl transport rc at all 3/3 sites.
+- Required linked email bytes to be ASCII and printable before constructing `MergeMessageField`; guarded construction sites 1/1.
+
+GREEN: message-field, exact-head, empty-UID/API, queue branch/repository/SHA, bash syntax, ShellCheck, and diff check pass. R7 total-removal mutants went RED: email guard 3 rows; bound switches 1 row; transport-rc guards 4 rows; HTTP-401 refusal 3 rows. R7 bound: mutants prove total removal only; explicit denominators above prove site coverage.

packages/mosaic/framework/tools/git/detect-platform.sh

@@ -5,7 +5,10 @@
 
 detect_platform() {
     local remote_url
-    remote_url=$(git remote get-url origin 2>/dev/null)
+    # `|| true` is load-bearing under `set -e`: outside a git repo this returns 128 and
+    # kills the CALLER before the -z check below can run, so the error message that is
+    # already written here was unreachable. Same idiom as get_gitea_repo_args() below.
+    remote_url=$(git remote get-url origin 2>/dev/null) || true
 
     if [[ -z "$remote_url" ]]; then
         echo "error: not a git repository or no origin remote" >&2
@@ -39,7 +42,10 @@ detect_platform() {
 
 get_repo_info() {
     local remote_url
-    remote_url=$(git remote get-url origin 2>/dev/null)
+    # `|| true` is load-bearing under `set -e`: outside a git repo this returns 128 and
+    # kills the CALLER before the -z check below can run, so the error message that is
+    # already written here was unreachable. Same idiom as get_gitea_repo_args() below.
+    remote_url=$(git remote get-url origin 2>/dev/null) || true
 
     if [[ -z "$remote_url" ]]; then
         echo "error: not a git repository or no origin remote" >&2
@@ -240,6 +246,21 @@ PY
     } >&2
 }
 
+# Explain tea's most misleading failure. `user does not exist [uid: 0, name: ]` reads
+# as a missing account; it almost always means a REVOKED OR STALE TOKEN. `tea login`
+# keeps its OWN COPY of the token, so rotating the credential store does not update it.
+# Diagnostic only -- stderr, no control flow, no exit.
+explain_tea_user_does_not_exist() {
+    cat >&2 <<'MSG'
+NOTE: `user does not exist [uid: 0, name: ]` from tea usually means a REVOKED OR STALE TOKEN,
+      not a missing account. A `tea login` stores its OWN COPY of the token; rotating the
+      credential store does NOT update it.
+      CHECK: the login's cached copy (`tea login list` -- read the FULL table, never `| head`),
+             then re-register that login against the current token.
+      DO NOT probe capability with a mutating request; a POST is the action, not a check.
+MSG
+}
+
 get_gitea_login_for_host() {
     local host="${1:-}"
     local login

packages/mosaic/framework/tools/git/issue-close.sh

@@ -91,13 +91,32 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
     GITEA_LOGIN_NAME=$(get_gitea_login || true)
     if [[ -n "$GITEA_LOGIN_NAME" ]]; then
         if [[ -n "$COMMENT" ]]; then
-            tea issue comment "$ISSUE_NUMBER" "$COMMENT" --repo "$OWNER/$REPO" --login "$GITEA_LOGIN_NAME"
+            # `tea issue comment` is NOT a subcommand -- tea 0.11.x lists only
+            # list/create/edit/reopen/close under `tea issue`. Comments are the
+            # TOP-LEVEL `tea comment`, which takes the same --repo/--login flags.
+            # The old call therefore always failed, was unchecked, and the script
+            # closed the issue anyway, losing the record of WHY.
+            #
+            # Use `tea comment` rather than the API helper so the comment and the
+            # close are made by the SAME principal ($GITEA_LOGIN_NAME). Routing the
+            # comment through the token-authenticated helper here would attribute the
+            # comment to the token holder and the close to the tea login -- two
+            # principals for one operation.
+            tea comment "$ISSUE_NUMBER" "$COMMENT" --repo "$OWNER/$REPO" --login "$GITEA_LOGIN_NAME" || {
+                echo "Error: failed to post comment on #$ISSUE_NUMBER -- NOT closing (fail closed)." >&2
+                exit 1
+            }
         fi
         tea issue close "$ISSUE_NUMBER" --repo "$OWNER/$REPO" --login "$GITEA_LOGIN_NAME"
     else
         echo "No tea login configured for $(get_remote_host); using authenticated Gitea API fallback." >&2
         if [[ -n "$COMMENT" ]]; then
-            gitea_issue_comment_api
+            # Fail closed here too: an unchecked comment lets the issue close without its
+            # audit trail, which is the same defect as the tea path above.
+            gitea_issue_comment_api || {
+                echo "Error: failed to post comment on #$ISSUE_NUMBER -- NOT closing (fail closed)." >&2
+                exit 1
+            }
         fi
         gitea_issue_close_api
     fi

packages/mosaic/framework/tools/git/issue-create.sh

@@ -156,6 +156,7 @@ case "$PLATFORM" in
                 exit 0
             fi
             echo "Warning: tea issue create failed, trying Gitea API fallback..." >&2
+            { declare -F explain_tea_user_does_not_exist >/dev/null && explain_tea_user_does_not_exist; } || true
         fi
         gitea_issue_create_api
         ;;

packages/mosaic/framework/tools/git/issue-view.sh

@@ -71,6 +71,7 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
             exit 0
         fi
         echo "Warning: tea issue view failed, trying Gitea API fallback..." >&2
+        { declare -F explain_tea_user_does_not_exist >/dev/null && explain_tea_user_does_not_exist; } || true
     fi
     gitea_issue_view_api
 else

packages/mosaic/framework/tools/git/pr-create.sh

@@ -219,6 +219,7 @@ case "$PLATFORM" in
             exit 0
         fi
         echo "Warning: tea pr create failed, trying Gitea API fallback..." >&2
+        { declare -F explain_tea_user_does_not_exist >/dev/null && explain_tea_user_does_not_exist; } || true
         gitea_pr_create_api
         ;;
     *)

packages/mosaic/framework/tools/git/pr-merge.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 # pr-merge.sh - Merge pull requests on Gitea or GitHub
-# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d]
+# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d] [--expect-head SHA] [--co-author-trailers --escalate-to PRINCIPAL]
 
 set -euo pipefail
 
@@ -14,6 +14,8 @@ MERGE_METHOD="squash"
 DELETE_BRANCH=false
 DRY_RUN=false
 EXPECT_HEAD=""
+CO_AUTHOR_TRAILERS=false
+ESCALATE_TO=""
 
 usage() {
     cat <<EOF
@@ -27,12 +29,16 @@ Options:
     -d, --delete-branch     Delete the head branch after merge
         --dry-run           Run metadata/login preflight without merging
         --expect-head SHA   Refuse unless the PR head matches this full commit SHA
+        --co-author-trailers Build verified trailers from linked PR commit authors
+        --escalate-to NAME  Named principal for an unresolved-author BLOCK
     -h, --help              Show this help message
 
 Examples:
     $(basename "$0") -n 42                    # Merge PR #42
     $(basename "$0") -n 42 -m squash          # Squash merge
     $(basename "$0") -n 42 -d                 # Squash merge and delete branch
+    $(basename "$0") -n 42 --expect-head 0123456789abcdef0123456789abcdef01234567
+    $(basename "$0") -n 42 --co-author-trailers --escalate-to tl-mosaic
 EOF
     exit "${1:-1}"
 }
@@ -57,9 +63,25 @@ while [[ $# -gt 0 ]]; do
             shift
             ;;
         --expect-head)
+            if [[ $# -lt 2 ]]; then
+                echo "Error: --expect-head requires one full commit SHA." >&2
+                exit 1
+            fi
             EXPECT_HEAD="$2"
             shift 2
             ;;
+        --co-author-trailers)
+            CO_AUTHOR_TRAILERS=true
+            shift
+            ;;
+        --escalate-to)
+            if [[ $# -lt 2 ]]; then
+                echo "Error: --escalate-to requires one principal name." >&2
+                exit 1
+            fi
+            ESCALATE_TO="$2"
+            shift 2
+            ;;
         -h|--help)
             usage 0
             ;;
@@ -88,17 +110,30 @@ if [[ -n "$EXPECT_HEAD" && ! "$EXPECT_HEAD" =~ ^[0-9a-fA-F]{40}$ ]]; then
     echo "Error: --expect-head must be a full 40-character hexadecimal commit SHA." >&2
     exit 1
 fi
+if [[ "$CO_AUTHOR_TRAILERS" == true && -z "$ESCALATE_TO" ]]; then
+    echo "Error: --co-author-trailers requires --escalate-to with a named principal." >&2
+    exit 1
+fi
+if [[ -n "$ESCALATE_TO" && ! "$ESCALATE_TO" =~ ^[A-Za-z0-9_.-]+$ ]]; then
+    echo "Error: --escalate-to must be one exact principal name." >&2
+    exit 1
+fi
+if [[ "$CO_AUTHOR_TRAILERS" != true && -n "$ESCALATE_TO" ]]; then
+    echo "Error: --escalate-to is valid only with --co-author-trailers." >&2
+    exit 1
+fi
 
 PR_METADATA="$("$SCRIPT_DIR/pr-metadata.sh" -n "$PR_NUMBER")"
 BASE_BRANCH="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("baseRefName") or "").strip())')"
 HEAD_BRANCH="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("headRefName") or "").strip())')"
 HEAD_SHA="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("headRefOid") or "").strip())')"
 HEAD_REPO="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; value=json.load(sys.stdin).get("headRepository") or ""; print((value.get("nameWithOwner") or value.get("full_name") or "") if isinstance(value, dict) else str(value).strip())')"
+PR_TITLE="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; print((json.load(sys.stdin).get("title") or "").strip())')"
+PR_AUTHOR="$(printf '%s' "$PR_METADATA" | python3 -c 'import json, sys; value=json.load(sys.stdin).get("author") or ""; print((value.get("login") or "").strip() if isinstance(value, dict) else str(value).strip())')"
 if [[ "$BASE_BRANCH" != "main" ]]; then
     echo "Error: Mosaic policy allows merges only for PRs targeting 'main' (found '$BASE_BRANCH')." >&2
     exit 1
 fi
-
 if [[ -z "$HEAD_BRANCH" || -z "$HEAD_REPO" || ! "$HEAD_SHA" =~ ^[0-9a-fA-F]{40}$ ]]; then
     echo "Error: Could not resolve the PR head branch, repository, and full commit SHA for queue inspection." >&2
     exit 1
@@ -122,70 +157,442 @@ PLATFORM=$(detect_platform)
 OWNER=$(get_repo_owner)
 REPO=$(get_repo_name)
 
-merge_gitea_with_api() {
-    local host="$1" api_url token basic_auth body_file raw_code payload
-    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/merge"
-    mkdir -p "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
-    body_file=$(mktemp "${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}/pr-merge-api-response.XXXXXX")
-    payload=$(python3 - "$HEAD_SHA" "$DELETE_BRANCH" <<'PY'
+write_curl_auth_config() {
+    local mode="$1" credential="$2"
+    printf '%s' "$credential" | python3 -c '
+import sys
+mode = sys.argv[1]
+credential = sys.stdin.read()
+if not credential or any(char in credential for char in "\r\n"):
+    raise SystemExit(1)
+escaped = credential.replace("\\", "\\\\").replace("\"", "\\\"")
+if mode == "token":
+    print(f"header = \"Authorization: token {escaped}\"")
+elif mode == "basic":
+    print(f"user = \"{escaped}\"")
+else:
+    raise SystemExit(1)
+' "$mode"
+}
+
+LAST_GITEA_HTTP_CODE="000"
+LAST_GITEA_ERROR=""
+MERGE_TEMP_DIRS=()
+GITEA_CURL_MAX_BYTES="${MOSAIC_GITEA_CURL_MAX_BYTES:-1048576}"
+GITEA_CURL_MAX_TIME="${MOSAIC_GITEA_CURL_MAX_TIME_SEC:-30}"
+GITEA_CURL_CONNECT_TIMEOUT="${MOSAIC_GITEA_CURL_CONNECT_TIMEOUT_SEC:-10}"
+for bound in "$GITEA_CURL_MAX_BYTES" "$GITEA_CURL_MAX_TIME" "$GITEA_CURL_CONNECT_TIMEOUT"; do
+    if [[ ! "$bound" =~ ^[1-9][0-9]*$ ]]; then
+        echo "Error: Gitea curl bounds must be positive integers; refusing request." >&2
+        exit 1
+    fi
+done
+GITEA_CURL_BOUNDS=(
+    --max-filesize "$GITEA_CURL_MAX_BYTES"
+    --max-time "$GITEA_CURL_MAX_TIME"
+    --connect-timeout "$GITEA_CURL_CONNECT_TIMEOUT"
+)
+
+format_gitea_error_response() {
+    local response_file="$1"
+    python3 - "$response_file" <<'PY'
 import json
 import sys
 
-head_sha, delete_branch = sys.argv[1:]
+with open(sys.argv[1], "rb") as handle:
+    raw = handle.read(65536)
+try:
+    response = json.loads(raw.decode("utf-8", errors="replace"))
+except (UnicodeDecodeError, json.JSONDecodeError):
+    message = "non-JSON response omitted"
+else:
+    if isinstance(response, dict):
+        message = response.get("message") or response.get("error")
+        if not message and response.get("errors") is not None:
+            message = json.dumps(response["errors"], separators=(",", ":"))
+    else:
+        message = None
+    if not message:
+        message = "JSON response contained no error message"
+message = str(message)
+if len(message) > 500:
+    message = message[:500] + "..."
+print(ascii(message))
+PY
+}
+
+cleanup_merge_temp_dirs() {
+    local path
+    for path in "${MERGE_TEMP_DIRS[@]}"; do
+        [[ -n "$path" ]] && rm -rf -- "$path"
+    done
+}
+trap cleanup_merge_temp_dirs EXIT
+trap 'exit 130' INT
+trap 'exit 143' TERM
+
+fetch_gitea_pr_head() {
+    local host="$1" auth_mode="$2" credential="$3" work_root="$4"
+    local response_file raw_code api_url auth_config curl_rc
+    response_file=$(mktemp "$work_root/pr-merge-pr.XXXXXX")
+    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}"
+    if ! auth_config=$(write_curl_auth_config "$auth_mode" "$credential"); then
+        echo "Error: Could not construct Gitea authentication config; refusing request." >&2
+        rm -f "$response_file"
+        return 1
+    fi
+    raw_code=$(curl -sS -K - "${GITEA_CURL_BOUNDS[@]}" -w '%{http_code}' -o "$response_file" \
+        -H "User-Agent: curl/8" "$api_url" <<<"$auth_config")
+    curl_rc=$?
+    LAST_GITEA_HTTP_CODE="${raw_code:-000}"
+    if [[ "$curl_rc" -ne 0 ]]; then
+        LAST_GITEA_ERROR="curl transport failed (rc=$curl_rc)"
+        rm -f "$response_file"
+        return 1
+    fi
+    if [[ ! "$raw_code" =~ ^2 ]]; then
+        LAST_GITEA_ERROR=$(format_gitea_error_response "$response_file")
+        rm -f "$response_file"
+        return 1
+    fi
+    if ! python3 - "$response_file" <<'PY'
+import json
+import re
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    pull = json.load(handle)
+head = pull.get("head") if isinstance(pull, dict) else None
+sha = str(head.get("sha") or "") if isinstance(head, dict) else ""
+if not re.fullmatch(r"[0-9a-fA-F]{40}", sha):
+    raise SystemExit(1)
+print(sha)
+PY
+    then
+        echo "Error: Gitea PR response has no valid head SHA; refusing merge." >&2
+        rm -f "$response_file"
+        return 1
+    fi
+    rm -f "$response_file"
+}
+
+fetch_gitea_pr_commits() {
+    local host="$1" auth_mode="$2" credential="$3" work_root="$4"
+    local page page_file combined_file merged_file raw_code page_count api_url auth_config curl_rc
+    mkdir -p "$work_root"
+    if ! auth_config=$(write_curl_auth_config "$auth_mode" "$credential"); then
+        echo "Error: Could not construct Gitea authentication config; refusing request." >&2
+        return 1
+    fi
+    combined_file=$(mktemp "$work_root/pr-merge-commits.XXXXXX")
+    printf '[]' > "$combined_file"
+
+    page=1
+    while true; do
+        page_file=$(mktemp "$work_root/pr-merge-commits-page.XXXXXX")
+        api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/commits?limit=50&page=${page}"
+        raw_code=$(curl -sS -K - "${GITEA_CURL_BOUNDS[@]}" -w '%{http_code}' -o "$page_file" \
+            -H "User-Agent: curl/8" "$api_url" <<<"$auth_config")
+        curl_rc=$?
+        LAST_GITEA_HTTP_CODE="${raw_code:-000}"
+        if [[ "$curl_rc" -ne 0 ]]; then
+            LAST_GITEA_ERROR="curl transport failed (rc=$curl_rc)"
+            rm -f "$page_file" "$combined_file"
+            return 1
+        fi
+        if [[ ! "$raw_code" =~ ^2 ]]; then
+            LAST_GITEA_ERROR=$(format_gitea_error_response "$page_file")
+            rm -f "$page_file" "$combined_file"
+            return 1
+        fi
+
+        if ! page_count=$(python3 - "$page_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    page = json.load(handle)
+if not isinstance(page, list):
+    raise SystemExit(1)
+print(len(page))
+PY
+        ); then
+            echo "Error: Gitea PR commits response is not a JSON array; refusing merge." >&2
+            rm -f "$page_file" "$combined_file"
+            return 1
+        fi
+
+        merged_file=$(mktemp "$work_root/pr-merge-commits-merged.XXXXXX")
+        if ! python3 - "$combined_file" "$page_file" > "$merged_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    combined = json.load(handle)
+with open(sys.argv[2], encoding="utf-8") as handle:
+    page = json.load(handle)
+json.dump(combined + page, sys.stdout, separators=(",", ":"))
+PY
+        then
+            echo "Error: Could not combine paginated PR commit metadata; refusing merge." >&2
+            rm -f "$page_file" "$combined_file" "$merged_file"
+            return 1
+        fi
+        mv "$merged_file" "$combined_file"
+        rm -f "$page_file"
+
+        if [[ "$page_count" -lt 50 ]]; then
+            break
+        fi
+        page=$((page + 1))
+        if [[ "$page" -gt 1000 ]]; then
+            echo "Error: PR commit pagination exceeded 1000 pages; refusing merge." >&2
+            rm -f "$combined_file"
+            return 1
+        fi
+    done
+
+    cat "$combined_file"
+    rm -f "$combined_file"
+}
+
+# LIMITATION: author.login resolution proves the commit address maps to a registered account.
+# It does NOT prove the named principal authored the commit — git author metadata is self-asserted.
+# This gate checks ATTRIBUTION LINKAGE, not AUTHORSHIP. Commit signing is out of scope and unadopted.
+build_coauthor_message_fields() {
+    local commits_file="$1" context_file="$2" head_file="$3"
+    python3 - "$commits_file" "$context_file" "$head_file" <<'PY'
+import json
+import re
+import sys
+
+commits_path, context_path, head_path = sys.argv[1:]
+with open(commits_path, encoding="utf-8") as handle:
+    commits = json.load(handle)
+head_sha = open(head_path, encoding="utf-8").read().strip()
+context_parts = open(context_path, "rb").read().split(b"\0")
+if len(context_parts) != 4 or context_parts[-1] != b"":
+    raise SystemExit(1)
+poster, title, principal = (part.decode("utf-8") for part in context_parts[:3])
+
+if not isinstance(commits, list) or not commits:
+    print(
+        f"BLOCK: provider returned no PR commits; author identity is unmeasurable. "
+        f"Refusing merge; escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+if not poster:
+    print(
+        f"BLOCK: PR poster login is empty; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+
+if not re.fullmatch(r"[0-9a-fA-F]{40}", head_sha):
+    print(
+        f"BLOCK: inspected PR head SHA is invalid; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+
+seen = set()
+trailers = []
+head_seen = False
+for item in commits:
+    if not isinstance(item, dict):
+        print(f"BLOCK: malformed PR commit metadata; escalate to named principal '{principal}'.", file=sys.stderr)
+        raise SystemExit(75)
+    sha = str(item.get("sha") or "<unknown>")
+    if sha == head_sha:
+        head_seen = True
+    commit = item.get("commit") if isinstance(item.get("commit"), dict) else {}
+    commit_author = commit.get("author") if isinstance(commit.get("author"), dict) else {}
+    email = str(commit_author.get("email") or "").strip()
+    provider_author = item.get("author") if isinstance(item.get("author"), dict) else {}
+    login = str(provider_author.get("login") or "").strip()
+
+    if not login:
+        diagnostic_email = email or "<missing>"
+        print(
+            f"BLOCK: commit {sha!r} has author.login=NULL while "
+            f"commit.author.email={diagnostic_email!r}; refusing merge; "
+            f"escalate to named principal '{principal}'.",
+            file=sys.stderr,
+        )
+        raise SystemExit(75)
+    if (
+        not email.isascii()
+        or not email.isprintable()
+        or not re.fullmatch(r"[A-Za-z0-9_.-]+", login)
+        or not re.fullmatch(r"[^<>\s]+@[^<>\s]+", email)
+    ):
+        print(
+            f"BLOCK: commit {sha!r} has unusable linked identity "
+            f"author.login={login!r}, commit.author.email={email!r}; refusing merge; "
+            f"escalate to named principal '{principal}'.",
+            file=sys.stderr,
+        )
+        raise SystemExit(75)
+    if login == poster or login in seen:
+        continue
+    seen.add(login)
+    trailers.append(f"Co-authored-by: {login} <{email}>")
+
+if not head_seen:
+    print(
+        f"BLOCK: inspected PR head is absent from commit enumeration; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+if not trailers:
+    print("{}")
+    raise SystemExit(0)
+if not title:
+    print(
+        f"BLOCK: PR title is empty; refusing merge; escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+if not title.isprintable() or re.match(r"^[A-Za-z-]+-[Bb]y:", title):
+    print(
+        f"BLOCK: PR title is not one printable, non-trailer line; refusing merge; "
+        f"escalate to named principal '{principal}'.",
+        file=sys.stderr,
+    )
+    raise SystemExit(75)
+
+print(json.dumps({
+    "MergeTitleField": title,
+    "MergeMessageField": "\n".join(trailers),
+}, separators=(",", ":")))
+PY
+}
+
+merge_gitea_api_attempt() {
+    local host="$1" auth_mode="$2" credential="$3"
+    local api_url attempt_dir body_file raw_code commits_file fields_file context_file head_file payload_file work_root attempt_rc auth_config curl_rc
+    LAST_GITEA_HTTP_CODE="000"
+    LAST_GITEA_ERROR=""
+    api_url="https://${host}/api/v1/repos/${OWNER}/${REPO}/pulls/${PR_NUMBER}/merge"
+    work_root="${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
+    mkdir -p "$work_root"
+    attempt_dir=$(mktemp -d "$work_root/pr-merge-attempt.XXXXXX")
+    chmod 0700 "$attempt_dir"
+    MERGE_TEMP_DIRS+=("$attempt_dir")
+    body_file=$(mktemp "$attempt_dir/api-response.XXXXXX")
+    fields_file=$(mktemp "$attempt_dir/message-fields.XXXXXX")
+    payload_file=$(mktemp "$attempt_dir/payload.XXXXXX")
+    printf '{}' > "$fields_file"
+
+    if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
+        commits_file=$(mktemp "$attempt_dir/pr-merge-commits-input.XXXXXX")
+        context_file=$(mktemp "$attempt_dir/pr-merge-message-context.XXXXXX")
+        head_file=$(mktemp "$attempt_dir/pr-merge-head-input.XXXXXX")
+        printf '%s\0%s\0%s\0' "$PR_AUTHOR" "$PR_TITLE" "$ESCALATE_TO" > "$context_file"
+        if fetch_gitea_pr_head "$host" "$auth_mode" "$credential" "$attempt_dir" > "$head_file"; then
+            :
+        else
+            attempt_rc=$?
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return "$attempt_rc"
+        fi
+        if [[ "$(<"$head_file")" != "$HEAD_SHA" ]]; then
+            echo "BLOCK: authenticated PR head moved from reviewed $HEAD_SHA to $(<"$head_file"); refusing merge; escalate to named principal '$ESCALATE_TO'." >&2
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return 75
+        fi
+        if fetch_gitea_pr_commits "$host" "$auth_mode" "$credential" "$attempt_dir" > "$commits_file"; then
+            :
+        else
+            attempt_rc=$?
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return "$attempt_rc"
+        fi
+        if build_coauthor_message_fields "$commits_file" "$context_file" "$head_file" > "$fields_file"; then
+            :
+        else
+            attempt_rc=$?
+            rm -f "$body_file" "$fields_file" "$payload_file" "$commits_file" "$context_file" "$head_file"
+            return "$attempt_rc"
+        fi
+        rm -f "$commits_file" "$context_file" "$head_file"
+    fi
+
+    if ! python3 - "$fields_file" "$HEAD_SHA" "$DELETE_BRANCH" > "$payload_file" <<'PY'
+import json
+import sys
+
+with open(sys.argv[1], encoding="utf-8") as handle:
+    fields = json.load(handle)
+head_sha, delete_branch = sys.argv[2:]
 payload = {"Do": "squash", "head_commit_id": head_sha}
 if delete_branch == "true":
     payload["delete_branch_after_merge"] = True
+payload.update(fields)
+allowed = {"Do", "head_commit_id", "delete_branch_after_merge", "MergeTitleField", "MergeMessageField"}
+if payload.get("Do") != "squash" or set(payload) - allowed:
+    raise SystemExit(1)
 print(json.dumps(payload, separators=(",", ":")))
 PY
-)
-
-    token=$(get_gitea_token "$host" || true)
-    if [[ -n "$token" ]]; then
-        raw_code=$(curl -sS -w '%{http_code}' -o "$body_file" \
-            -X POST \
-            -H "User-Agent: curl/8" \
-            -H "Authorization: token $token" \
-            -H 'Content-Type: application/json' \
-            -d "$payload" \
-            "$api_url" || true)
-        if [[ "$raw_code" =~ ^2 ]]; then
-            rm -f "$body_file"
-            return 0
-        fi
+    then
+        rm -f "$body_file" "$fields_file" "$payload_file"
+        return 1
     fi
+    rm -f "$fields_file"
 
-    basic_auth=$(get_gitea_basic_auth "$host" || true)
-    if [[ -n "$basic_auth" ]]; then
-        raw_code=$(curl -sS -w '%{http_code}' -o "$body_file" \
-            -X POST \
-            -u "$basic_auth" \
-            -H "User-Agent: curl/8" \
-            -H 'Content-Type: application/json' \
-            -d "$payload" \
-            "$api_url" || true)
-        if [[ "$raw_code" =~ ^2 ]]; then
-            rm -f "$body_file"
-            return 0
-        fi
+    if ! auth_config=$(write_curl_auth_config "$auth_mode" "$credential"); then
+        echo "Error: Could not construct Gitea authentication config; refusing request." >&2
+        rm -f "$body_file" "$payload_file"
+        return 1
     fi
+    raw_code=$(curl -sS -K - "${GITEA_CURL_BOUNDS[@]}" -w '%{http_code}' -o "$body_file" \
+        -X POST -H "User-Agent: curl/8" \
+        -H 'Content-Type: application/json' \
+        --data-binary "@$payload_file" "$api_url" <<<"$auth_config")
+    curl_rc=$?
+    LAST_GITEA_HTTP_CODE="${raw_code:-000}"
+    if [[ "$curl_rc" -ne 0 ]]; then
+        LAST_GITEA_ERROR="curl transport failed (rc=$curl_rc)"
+        rm -f "$body_file" "$payload_file"
+        rm -rf -- "$attempt_dir"
+        return 1
+    fi
+    if [[ ! "$raw_code" =~ ^2 ]]; then
+        LAST_GITEA_ERROR=$(format_gitea_error_response "$body_file")
+    fi
+    rm -f "$body_file" "$payload_file"
+    rm -rf -- "$attempt_dir"
+    [[ "$raw_code" =~ ^2 ]]
+}
 
-    python3 - "${raw_code:-000}" "$body_file" <<'PY' >&2
-import json
-import sys
-code, path = sys.argv[1], sys.argv[2]
-try:
-    with open(path, encoding="utf-8", errors="replace") as handle:
-        raw = handle.read(500)
-    data = json.loads(raw) if raw else {}
-    message = data.get("message") or data.get("error") or raw or "empty response"
-except Exception:
-    try:
-        message = open(path, encoding="utf-8", errors="replace").read(500) or "empty response"
-    except Exception:
-        message = "unreadable response"
-print(f"Error: Gitea API merge failed with HTTP {code}: {message}")
-PY
-    rm -f "$body_file"
+merge_gitea_with_api() {
+    local host="$1" token attempt_rc
+
+    if ! token=$(get_gitea_token "$host"); then
+        echo "Error: Could not resolve the required Gitea token; refusing merge without changing principals." >&2
+        return 1
+    fi
+    if [[ -z "$token" ]]; then
+        echo "Error: Required Gitea token resolved empty; refusing merge without changing principals." >&2
+        return 1
+    fi
+    if merge_gitea_api_attempt "$host" token "$token"; then
+        return 0
+    else
+        attempt_rc=$?
+    fi
+    if [[ "$attempt_rc" -eq 75 ]]; then
+        return 75
+    fi
+    if [[ "$LAST_GITEA_HTTP_CODE" != "401" ]]; then
+        echo "Error: Gitea API merge failed with the identity-bound token (HTTP ${LAST_GITEA_HTTP_CODE:-000}).${LAST_GITEA_ERROR:+ Provider response: $LAST_GITEA_ERROR}" >&2
+        return 1
+    fi
+    echo "Error: Gitea API rejected the identity-bound token with HTTP 401; refusing cross-principal credential fallback." >&2
     return 1
 }
 
@@ -195,11 +602,10 @@ if [[ "$DRY_RUN" == true ]]; then
             echo "Error: Cannot determine host from origin remote URL" >&2
             exit 1
         }
-        TEA_LOGIN="$(get_gitea_login_for_host "$HOST" || true)"
-        if [[ -n "$TEA_LOGIN" ]]; then
-            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with tea login '$TEA_LOGIN' (base=$BASE_BRANCH, method=squash)."
+        if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
+            echo "Dry run: would verify PR commit authors and merge PR #$PR_NUMBER on $HOST with authenticated Gitea API message fields (base=$BASE_BRANCH, method=squash)."
         else
-            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with authenticated Gitea API fallback (base=$BASE_BRANCH, method=squash)."
+            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with the authenticated exact-head Gitea API path (base=$BASE_BRANCH, method=squash)."
         fi
     else
         echo "Dry run: would merge PR #$PR_NUMBER on $PLATFORM (base=$BASE_BRANCH, method=squash)."
@@ -209,6 +615,10 @@ fi
 
 case "$PLATFORM" in
     github)
+        if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
+            echo "Error: --co-author-trailers currently requires the Gitea REST message-field contract." >&2
+            exit 1
+        fi
         cmd=(gh pr merge "$PR_NUMBER" --squash --match-head-commit "$HEAD_SHA")
         [[ "$DELETE_BRANCH" == true ]] && cmd+=(--delete-branch)
         "${cmd[@]}"
@@ -219,7 +629,7 @@ case "$PLATFORM" in
             exit 1
         }
         # Gitea's API head_commit_id is an atomic compare-and-merge precondition.
-        # tea cannot express it, so exact-head merges use the authenticated API path.
+        # tea cannot express it, so every Gitea merge uses the authenticated API path.
         merge_gitea_with_api "$HOST"
         ;;
     *)

packages/mosaic/framework/tools/git/test-ci-queue-wait-tristate.sh

@@ -9,10 +9,51 @@ WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/ci-queue-wait-tristate}
 REPO_DIR="$WORK_DIR/repo"
 STUB_DIR="$WORK_DIR/stubs"
 AUDIT_LOG="$WORK_DIR/audit/ci-queue-wait.jsonl"
+STATUS_OBSERVED="$WORK_DIR/status-observed"
+CLOCK_LOG="$WORK_DIR/clock.log"
+WATCHDOG_PYTHON="/usr/bin/python3"
+WATCHDOG_SCRIPT="$WORK_DIR/real-clock-watchdog.py"
+WATCHDOG_TIMEOUT_SEC=5
+WATCHDOG_EXIT=90
 FEATURE_BRANCH="fix/rm-03-fixture"
 
+if [[ ! -x "$WATCHDOG_PYTHON" ]]; then
+    echo "FAIL setup: required real-clock watchdog runtime is unavailable at $WATCHDOG_PYTHON" >&2
+    exit 1
+fi
+
 rm -rf "$WORK_DIR"
 mkdir -p "$REPO_DIR" "$STUB_DIR"
+cat > "$WATCHDOG_SCRIPT" <<'PY'
+import os
+import signal
+import subprocess
+import sys
+
+if len(sys.argv) < 3:
+    raise SystemExit(2)
+
+timeout_seconds = float(sys.argv[1])
+process = subprocess.Popen(sys.argv[2:], start_new_session=True)
+try:
+    return_code = process.wait(timeout=timeout_seconds)
+except subprocess.TimeoutExpired:
+    try:
+        os.killpg(process.pid, signal.SIGKILL)
+    except ProcessLookupError:
+        pass
+    process.wait()
+    print(
+        f"FAIL HANG watchdog: subject exceeded {timeout_seconds:g}s "
+        "before completing its intended path",
+        file=sys.stderr,
+    )
+    raise SystemExit(90)
+
+if return_code < 0:
+    raise SystemExit(128 - return_code)
+raise SystemExit(return_code)
+PY
 git -C "$REPO_DIR" init -q
 git -C "$REPO_DIR" checkout -q -b "$FEATURE_BRANCH"
 git -C "$REPO_DIR" remote add origin https://git.example.test/acme/widgets.git
@@ -33,6 +74,9 @@ printf '%s\n' "$url" >> "${MOSAIC_STUB_URL_LOG:?}"
 
 case "$url" in
     */branches/*)
+        if [[ "${MOSAIC_STUB_BRANCH_MODE:-ok}" == "hang-before-provider" ]]; then
+            while :; do :; done
+        fi
         if [[ "${MOSAIC_STUB_BRANCH_MODE:-ok}" == "unreachable" ]]; then
             exit 7
         fi
@@ -44,6 +88,7 @@ case "$url" in
         fi
         ;;
     */status)
+        : > "${MOSAIC_STUB_STATUS_OBSERVED:?}"
         case "${MOSAIC_STUB_STATUS_MODE:?}" in
             success)   printf '%s' '{"state":"success","statuses":[{"status":"success"}]}' ;;
             pending)   printf '%s' '{"state":"pending","statuses":[{"status":"pending","context":"ci/test"}]}' ;;
@@ -63,7 +108,31 @@ case "$url" in
     *) echo "unexpected curl URL: $url" >&2; exit 2 ;;
 esac
 SH
-chmod +x "$STUB_DIR/curl"
+
+cat > "$STUB_DIR/date" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ "$#" -ne 1 || "$1" != "+%s" ]]; then
+    echo "unexpected date invocation: $*" >&2
+    exit 2
+fi
+
+if [[ -e "${MOSAIC_STUB_STATUS_OBSERVED:?}" ]]; then
+    printf 'date-phase=after-status\n' >> "${MOSAIC_STUB_CLOCK_LOG:?}"
+    printf '1002\n'
+else
+    printf 'date-phase=before-status\n' >> "${MOSAIC_STUB_CLOCK_LOG:?}"
+    printf '1000\n'
+fi
+SH
+
+cat > "$STUB_DIR/sleep" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+printf 'sleep-after-status=%s\n' "$*" >> "${MOSAIC_STUB_CLOCK_LOG:?}"
+SH
+chmod +x "$STUB_DIR/curl" "$STUB_DIR/date" "$STUB_DIR/sleep"
 
 run_guard() {
     local status_mode="$1"
@@ -83,13 +152,46 @@ run_guard() {
             export GITEA_URL=https://git.example.test
             export MOSAIC_STUB_STATUS_MODE="$status_mode"
         fi
+        rm -f "$STATUS_OBSERVED" "$CLOCK_LOG"
         export MOSAIC_STUB_URL_LOG="$WORK_DIR/urls.log"
+        export MOSAIC_STUB_STATUS_OBSERVED="$STATUS_OBSERVED"
+        export MOSAIC_STUB_CLOCK_LOG="$CLOCK_LOG"
         export MOSAIC_CI_QUEUE_AUDIT_LOG="$audit_log"
-        "$SCRIPT_DIR/ci-queue-wait.sh" --purpose "${MOSAIC_TEST_PURPOSE:-push}" -t 0 -i 0 "$@"
+        # Provider observation is the synchronization event. The one-second
+        # timeout is subject semantics under virtual time, never a wall wait.
+        # The absolute Python runtime uses an internal monotonic wait and kills
+        # the subject's isolated process group. Neither operation can resolve
+        # to the virtual date/sleep stubs at the front of PATH.
+        local subject_rc
+        if "$WATCHDOG_PYTHON" "$WATCHDOG_SCRIPT" "$WATCHDOG_TIMEOUT_SEC" \
+            "$SCRIPT_DIR/ci-queue-wait.sh" --purpose "${MOSAIC_TEST_PURPOSE:-push}" -t 1 -i 1 "$@"; then
+            subject_rc=0
+        else
+            subject_rc=$?
+        fi
+        return "$subject_rc"
     )
 }
 
 failures=0
+assert_provider_observed() {
+    local name="$1" require_expiration="${2:-0}"
+    if [[ ! -e "$STATUS_OBSERVED" ]]; then
+        echo "FAIL $name: status provider was not observed" >&2
+        failures=$((failures + 1))
+    fi
+    if [[ ! -s "$CLOCK_LOG" ]] || ! grep -q '^date-phase=before-status$' "$CLOCK_LOG"; then
+        echo "FAIL $name: virtual clock interception did not run before provider observation" >&2
+        failures=$((failures + 1))
+    fi
+    if [[ "$require_expiration" -eq 1 ]]; then
+        if ! grep -q '^sleep-after-status=' "$CLOCK_LOG" || ! grep -q '^date-phase=after-status$' "$CLOCK_LOG"; then
+            echo "FAIL $name: pending path did not expire after provider observation" >&2
+            failures=$((failures + 1))
+        fi
+    fi
+}
+
 run_assertion() {
     local name="$1" expected_rc="$2" status_mode="$3" required_text="$4"
     local output rc
@@ -124,6 +226,13 @@ run_assertion() {
         printf '%s\n' "$output" >&2
         failures=$((failures + 1))
     fi
+    if [[ "$status_mode" != "credential-unresolvable" ]]; then
+        if [[ "$status_mode" == "pending" ]]; then
+            assert_provider_observed "$name" 1
+        else
+            assert_provider_observed "$name"
+        fi
+    fi
 }
 
 set -e
@@ -140,6 +249,27 @@ run_assertion large-payload not126 large-success 'state=terminal-success'
 run_assertion credential-unresolvable zero credential-unresolvable 'CANNOT_ASSERT'
 run_assertion provider-unreachable zero unreachable 'CANNOT_ASSERT'
 
+# Positive liveness control: a subject mutant hangs before the branch lookup
+# can reach the status provider. Only the independent real-clock watchdog may
+# terminate it, and its failure must be distinct from subject timeout rc=124.
+set +e
+watchdog_output=$(MOSAIC_STUB_BRANCH_MODE=hang-before-provider run_guard success "$AUDIT_LOG" 2>&1)
+watchdog_rc=$?
+set -e
+if [[ "$watchdog_rc" -ne "$WATCHDOG_EXIT" ]]; then
+    echo "FAIL watchdog-control: expected hang-specific rc=$WATCHDOG_EXIT, got rc=$watchdog_rc" >&2
+    failures=$((failures + 1))
+fi
+if [[ "$watchdog_output" != *"FAIL HANG watchdog:"* ]]; then
+    echo "FAIL watchdog-control: expected distinct hang-specific diagnostic" >&2
+    printf '%s\n' "$watchdog_output" >&2
+    failures=$((failures + 1))
+fi
+if [[ -e "$STATUS_OBSERVED" ]]; then
+    echo "FAIL watchdog-control: hanging mutant unexpectedly reached the status provider" >&2
+    failures=$((failures + 1))
+fi
+
 if [[ ! -s "$AUDIT_LOG" ]] || ! grep -q '"outcome":"CANNOT_ASSERT"' "$AUDIT_LOG"; then
     echo "FAIL provider-unreachable-audit: expected durable CANNOT_ASSERT JSONL record" >&2
     failures=$((failures + 1))
@@ -160,6 +290,7 @@ if [[ "$merge_unreachable_output" != *"CANNOT_ASSERT"* ]]; then
     echo "FAIL merge-provider-unreachable: expected loud CANNOT_ASSERT diagnostic" >&2
     failures=$((failures + 1))
 fi
+assert_provider_observed merge-provider-unreachable
 merge_audit_lines_after=$(wc -l < "$AUDIT_LOG")
 if [[ "$merge_audit_lines_after" -le "$merge_audit_lines_before" ]]; then
     echo "FAIL merge-provider-unreachable: expected an additional audit record" >&2
@@ -223,6 +354,7 @@ if [[ "$audit_failure_output" != *"audit"* ]]; then
     echo "FAIL audit-unavailable: expected loud audit failure diagnostic" >&2
     failures=$((failures + 1))
 fi
+assert_provider_observed audit-unavailable
 
 if [[ "$failures" -ne 0 ]]; then
     echo "ci-queue-wait tri-state regression failed ($failures assertions)" >&2

packages/mosaic/framework/tools/git/test-detect-platform-outside-repo.sh

@@ -0,0 +1,58 @@
+#!/bin/bash
+# Regression: detect_platform / get_repo_info must FAIL LOUDLY outside a git repo,
+# not kill the caller silently.
+#
+# Both functions already contained the right error path:
+#     if [[ -z "$remote_url" ]]; then echo "error: not a git repository..." >&2; return 1; fi
+# but under `set -e` -- which every wrapper in this directory uses -- the preceding
+# assignment `remote_url=$(git remote get-url origin 2>/dev/null)` returns git's 128
+# outside a repo and terminates the CALLER first. The message was unreachable.
+#
+# Observed cost: pr-review.sh invoked from a non-repo cwd exits 128 with NO stdout and
+# NO stderr, even when -r/--repo and -H/--host are supplied -- the flags documented as
+# "skips git-remote inference". Two reviewer seats hit this and correctly reported
+# `blocked` with no diagnostic to report.
+#
+# The control that matters is the LOUD one: asserting "rc != 0" passes on the broken
+# build too, because 128 is also non-zero. The test must assert the MESSAGE.
+set -uo pipefail
+fail=0
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+TMP="$(mktemp -d)"; trap 'rm -rf "$TMP"' EXIT
+
+run_outside() { # $1=function name -> "rc:sawmessage"
+    local fn="$1" out rc
+    out=$( cd "$TMP" && bash -c "set -e; source '$HERE/detect-platform.sh'; $fn" 2>&1 ); rc=$?
+    printf '%s:%s' "$rc" "$(grep -qi 'not a git repository' <<<"$out" && echo yes || echo no)"
+}
+check() { if [ "$2" = "$3" ]; then echo "  PASS  $1 ($2)"; else echo "  FAIL  $1: got $2, want $3"; fail=1; fi; }
+
+# $TMP must not be inside a git repo. Do not SKIP on failure: be-coder-07 showed the
+# original SKIP exited 0, so pointing TMPDIR beneath a git worktree made this test PASS
+# against unchanged main. A skip that exits 0 is indistinguishable from a pass.
+# GIT_CEILING_DIRECTORIES stops git walking above $TMP, making the condition hold
+# regardless of where TMPDIR lives, rather than merely detecting when it does not.
+# GIT_CEILING_DIRECTORIES is matched against the PHYSICAL path -- a symlinked TMPDIR
+# (/tmp is commonly one) makes the logical path never match, and the ceiling silently
+# does nothing. Resolve it before exporting.
+TMP="$(cd "$TMP" && pwd -P)"
+export GIT_CEILING_DIRECTORIES="$TMP"
+if ( cd "$TMP" && git rev-parse --git-dir >/dev/null 2>&1 ); then
+    echo "  FAIL  scratch dir is inside a git repo even with GIT_CEILING_DIRECTORIES set;"
+    echo "        the outside-a-repo precondition cannot be established -- refusing to report a result"
+    exit 1
+fi
+
+echo "== outside a git repo: rc=1 AND the diagnostic is emitted =="
+check "detect_platform" "$(run_outside detect_platform)" "1:yes"
+check "get_repo_info"   "$(run_outside get_repo_info)"   "1:yes"
+
+echo "== inside a git repo the functions still work =="
+git init -q "$TMP/repo" 2>/dev/null
+git -C "$TMP/repo" remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git 2>/dev/null
+out=$( cd "$TMP/repo" && bash -c "set -e; source '$HERE/detect-platform.sh'; detect_platform" 2>&1 ); rc=$?
+if [ "$rc" -eq 0 ] && grep -qi 'gitea' <<<"$out"; then echo "  PASS  detect_platform in-repo (rc=0, $out)"
+else echo "  FAIL  detect_platform in-repo: rc=$rc out=$out"; fail=1; fi
+
+[ "$fail" -eq 0 ] && echo "OK  detect-platform fails loudly outside a repo" || echo "FAILED"
+exit "$fail"

packages/mosaic/framework/tools/git/test-explain-diagnostic-status-neutral.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+# Regression: the tea-failure diagnostic must be STATUS-NEUTRAL.
+#
+# Found by be-coder-08 reviewing PR #1086. At all three call sites the diagnostic is emitted
+# immediately BEFORE the Gitea API fallback. Written as the last command of an && list:
+#     declare -F explain_... >/dev/null && explain_...
+# under `set -e` a FAILING diagnostic exits and the fallback never runs -- a diagnostic that
+# suppresses the recovery path it exists to explain. It misbehaves ONLY when the helper is
+# PRESENT, so the helper-absent path (pre-#1086 behaviour) keeps working and reads as a
+# passing control.
+#
+# TWO DEFECTS IN THE FIRST VERSION OF THIS TEST, both found by be-coder-08:
+#   1. `out=$( ... ) 2>"$errto"` applies the redirection to the ASSIGNMENT, not to the
+#      command substitution, so the probe's stderr was never actually pointed at /dev/full
+#      and the /dev/full rows proved nothing. Verified: `out=$(echo x >&2) 2>/dev/full`
+#      leaks to the terminal and returns 0; the redirect must be INSIDE the substitution.
+#   2. `eval "$CONSTRUCT"` changes `set -e` semantics for a bare && list, so the probe did
+#      not exercise the construct as the shipped file executes it. It now writes the line
+#      into a real script and runs it -- same parse, same set -e rules, no eval.
+# The construct is still LIFTED FROM THE SHIPPED FILE: retyping the fixed form makes the
+# probe pass on a build whose real call sites still carry the bare && form.
+set -uo pipefail
+fail=0
+GIT_DIR_UNDER_TEST="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+TMP="$(mktemp -d)"; trap 'rm -rf "$TMP"' EXIT
+
+probe() { # $1=present|absent  $2=stderr target  $3=source file  -> "rc:fallback"
+    local helper="$1" errto="$2" src="$3" construct script out rc
+    construct=$(grep -m1 'explain_tea_user_does_not_exist' "$GIT_DIR_UNDER_TEST/$src" | sed 's/^[[:space:]]*//')
+    [ -n "$construct" ] || { printf 'no-construct:no'; return; }
+    script="$TMP/probe.sh"
+    {
+        echo '#!/bin/bash'
+        echo 'set -e'
+        echo 'explain_tea_user_does_not_exist() { echo "diagnostic" >&2; }'
+        [ "$helper" = absent ] && echo 'unset -f explain_tea_user_does_not_exist'
+        echo "$construct"                # the shipped line, parsed by a real shell
+        echo 'echo FALLBACK_REACHED'
+    } > "$script"
+    # redirect INSIDE the substitution so the subshell's stderr really is $errto
+    out=$( bash "$script" 2>"$errto" ); rc=$?
+    printf '%s:%s' "$rc" "$(grep -q FALLBACK_REACHED <<<"$out" && echo yes || echo no)"
+}
+
+check() { if [ "$2" = "$3" ]; then echo "  PASS  $1 ($2)"; else echo "  FAIL  $1: got $2, want $3"; fail=1; fi; }
+
+echo "== diagnostic must not alter exit status or skip the fallback =="
+# /dev/full makes every stderr write fail -- the real-world shape is a closed or full fd.
+for src in pr-create.sh issue-view.sh issue-create.sh; do
+    check "$src stderr OK      / helper present" "$(probe present /dev/null "$src")" "0:yes"
+    check "$src stderr OK      / helper absent " "$(probe absent  /dev/null "$src")" "0:yes"
+    check "$src stderr FAILING / helper present" "$(probe present /dev/full "$src")" "0:yes"
+    check "$src stderr FAILING / helper absent " "$(probe absent  /dev/full "$src")" "0:yes"
+done
+
+echo "== all three call sites use the status-neutral form =="
+for f in pr-create.sh issue-view.sh issue-create.sh; do
+    p="$GIT_DIR_UNDER_TEST/$f"
+    grep -q '{ declare -F explain_tea_user_does_not_exist >/dev/null && explain_tea_user_does_not_exist; } || true' "$p" \
+        && echo "  PASS  $f guarded" || { echo "  FAIL  $f: diagnostic is not status-neutral"; fail=1; }
+done
+
+[ "$fail" -eq 0 ] && echo "OK  diagnostic is status-neutral" || echo "FAILED"
+exit "$fail"

packages/mosaic/framework/tools/git/test-issue-close-fail-closed.sh

@@ -0,0 +1,150 @@
+#!/usr/bin/env bash
+# Regression: issue-close.sh must NOT close an issue when the closing comment could not
+# be posted, and comment+close must be made by ONE principal.
+#
+# Guards two defects fixed together (see #1081):
+#   1. `tea issue comment` is not a subcommand -- tea exposes comments as the TOP-LEVEL
+#      `tea comment`. The old call always failed, was unchecked, and the issue closed
+#      anyway, losing the record of WHY it was closed.
+#   2. Routing the comment through the token-authenticated API helper while the close
+#      used --login would attribute one operation to two principals.
+#
+# SAFETY (rev-974, #1085 review 130): this test previously ran under `set -uo pipefail`
+# with unchecked mkdir/redirect/cd, then prepended a possibly-nonexistent $MOCK_BIN to
+# PATH -- while `git remote add origin` names the REAL repository. Forcing setup failure
+# with an unwritable AGENT_WORK_ROOT made it `git init` in its CALLER's directory and
+# invoke the real, provider-mutating issue-close.sh. Setup now fails closed, and both
+# `tea` and `curl` are asserted to resolve INSIDE $MOCK_BIN before any target run.
+set -euo pipefail
+# NOTE: with `set -e`, `grep -q X && fail "..."` is a trap -- the ABSENT case (grep rc=1,
+# which is the PASSING case for a must-not-appear assertion) is the last command of an &&
+# list and silently terminates the script with no message. Every must-not-appear check
+# below is therefore an if-block. This is the same set -e + &&-list defect be-coder-08
+# found in #1086, reintroduced here by adding `set -e` for the sandbox-safety fix.
+
+WORK_ROOT="${AGENT_WORK_ROOT:-${TMPDIR:-/tmp}}"
+SANDBOX="$WORK_ROOT/issue-close-fail-closed-test-$$"
+MOCK_BIN="$SANDBOX/bin"; REPO_DIR="$SANDBOX/repo"; CALLS="$SANDBOX/calls.log"
+cleanup() { rm -rf "$SANDBOX"; }
+trap cleanup EXIT
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+TARGET="$SCRIPT_DIR/issue-close.sh"
+[ -f "$TARGET" ] || { echo "FAIL: issue-close.sh not found beside this test"; exit 1; }
+fail() { echo "FAIL: $*"; exit 1; }
+
+# Every setup step is checked. Under `set -e` these abort; the explicit || fail keeps the
+# reason legible instead of a bare non-zero exit.
+mkdir -p "$MOCK_BIN" "$REPO_DIR" || fail "setup: cannot create sandbox under $WORK_ROOT"
+: > "$CALLS"                     || fail "setup: cannot write calls log at $CALLS"
+cd "$REPO_DIR"                   || fail "setup: cannot cd into $REPO_DIR"
+git init -q                      || fail "setup: git init failed"
+git remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git || fail "setup: git remote add failed"
+export PATH="$MOCK_BIN:$PATH" CALLS
+export GITEA_URL="https://git.mosaicstack.dev"
+export GITEA_TOKEN="redacted-test-token"
+
+cat > "$MOCK_BIN/curl" <<'EOF'
+#!/bin/bash
+method=GET; url=""
+while [ $# -gt 0 ]; do
+    case "$1" in
+        -X) method="$2"; shift 2 ;;
+        http*|https*) url="$1"; shift ;;
+        *) shift ;;
+    esac
+done
+printf 'curl %s %s\n' "$method" "$url" >> "$CALLS"
+[ "${MOCK_CURL_FAIL:-}" = "1" ] && [ "$method" = "POST" ] && exit 22
+exit 0
+EOF
+chmod +x "$MOCK_BIN/curl"
+
+mk_tea() {  # $1 = exit code for a comment attempt; $2 = login list (empty => no login)
+    local rc="$1" login="${2-}"
+    cat > "$MOCK_BIN/tea" <<EOF
+#!/bin/bash
+printf 'tea %s\n' "\$*" >> "$CALLS"
+if [[ "\$*" == *"login list"* ]]; then
+    printf '%s\n' '${login}'; exit 0
+fi
+# Fail ANY comment attempt -- both the correct top-level \`tea comment\` and the broken
+# \`tea issue comment\` -- so an unfixed script exercises the DEFECT rather than tripping
+# a setup assertion.
+if [[ "\$1" == "comment" || ( "\$1" == "issue" && "\$2" == "comment" ) ]]; then exit $rc; fi
+exit 0
+EOF
+    chmod +x "$MOCK_BIN/tea"
+}
+LOGIN_JSON='[{"name":"git.mosaicstack.dev","url":"https://git.mosaicstack.dev"}]'
+
+# The mocks must be the ones that run. Without this, a failed setup silently falls through
+# to the real tea/curl and the "test" mutates the real provider.
+assert_mocked() {
+    local w
+    for w in tea curl; do
+        p=$(command -v "$w" || true)
+        [ -n "$p" ] || fail "SAFETY: $w does not resolve at all"
+        case "$p" in
+            "$MOCK_BIN"/*) : ;;
+            *) fail "SAFETY: $w resolves to $p, OUTSIDE the sandbox -- refusing to invoke the target" ;;
+        esac
+    done
+}
+
+run_target() {  # never let a target failure abort the test; we assert on rc
+    # Call sites MUST use `rc=0; run_target ... || rc=$?` -- a bare `run_target ...; rc=$?`
+    # lets the non-zero RETURN trip set -e in the CALLER before rc is ever read.
+    set +e; bash "$TARGET" "$@" >/dev/null 2>&1; local rc=$?; set -e; return $rc
+}
+
+# ── tea path ────────────────────────────────────────────────────────────────────────
+# 1. NEGATIVE (the regression): comment fails => must NOT close, must exit non-zero
+mk_tea 1 "$LOGIN_JSON"; : > "$CALLS"; assert_mocked
+rc=0; run_target -i 42 -c "closing note" || rc=$?
+grep -qE 'tea (issue )?comment' "$CALLS" || fail "no comment attempt -- setup did not reach the tea branch"
+if grep -q 'tea issue close' "$CALLS"; then fail "ISSUE CLOSED AFTER THE COMMENT FAILED -- the regression"; fi
+[ "$rc" -ne 0 ] || fail "comment failed but issue-close exited 0 -- FAIL-OPEN"
+
+# 2. POSITIVE: comment succeeds => close proceeds, exit 0
+mk_tea 0 "$LOGIN_JSON"; : > "$CALLS"; assert_mocked
+rc=0; run_target -i 42 -c "closing note" || rc=$?
+[ "$rc" -eq 0 ] || fail "comment succeeded but issue-close exited $rc"
+grep -q 'tea issue close' "$CALLS" || fail "issue not closed even though the comment succeeded"
+
+# 3. must use top-level `tea comment`, never `tea issue comment`
+if grep -q 'tea issue comment' "$CALLS"; then fail "used 'tea issue comment' -- not a valid subcommand"; fi
+
+# 4. ONE PRINCIPAL: comment and close must carry the SAME --login
+c=$(grep -m1 '^tea comment'     "$CALLS" | grep -o -- '--login [^ ]*' | awk '{print $2}')
+k=$(grep -m1 '^tea issue close' "$CALLS" | grep -o -- '--login [^ ]*' | awk '{print $2}')
+[ -n "$c" ] || fail "comment carried no --login"
+[ "$c" = "$k" ] || fail "MIXED PRINCIPALS: comment=$c close=$k"
+
+# ── no-login / API fallback path ────────────────────────────────────────────────────
+# rev-974: the delta also adds fail-closed behaviour to this branch, and the suite never
+# reached it -- replacing the whole fallback contract with an unconditional close still
+# passed. These assert the POSTCONDITION (which HTTP calls happened, in what order),
+# not merely that a command ran.
+# 5. no login + comment FAILS => POST attempted, NO PATCH, non-zero
+mk_tea 0 ""; : > "$CALLS"; assert_mocked
+rc=0; MOCK_CURL_FAIL=1 run_target -i 42 -c "closing note" || rc=$?
+grep -q 'curl POST' "$CALLS" || fail "API path: no comment POST attempted"
+if grep -q 'curl PATCH' "$CALLS"; then fail "API path: ISSUE CLOSED (PATCH) AFTER THE COMMENT POST FAILED"; fi
+[ "$rc" -ne 0 ] || fail "API path: comment failed but exited 0 -- FAIL-OPEN"
+
+# 6. no login + comment SUCCEEDS => POST strictly BEFORE PATCH, exit 0
+mk_tea 0 ""; : > "$CALLS"; assert_mocked
+rc=0; run_target -i 42 -c "closing note" || rc=$?
+[ "$rc" -eq 0 ] || fail "API path: comment succeeded but exited $rc"
+order=$(grep -oE 'curl (POST|PATCH)' "$CALLS" | awk '{print $2}' | paste -sd, -)
+[ "$order" = "POST,PATCH" ] || fail "API path: expected POST,PATCH -- got '${order:-<none>}'"
+
+# 7. no login + NO comment => PATCH only, never a POST
+mk_tea 0 ""; : > "$CALLS"; assert_mocked
+rc=0; run_target -i 42 || rc=$?
+[ "$rc" -eq 0 ] || fail "API path: no-comment close exited $rc"
+if grep -q 'curl POST' "$CALLS"; then fail "API path: posted a comment when none was requested"; fi
+grep -q 'curl PATCH' "$CALLS" || fail "API path: issue not closed when no comment was requested"
+
+echo "issue-close.sh fail-closed + single-principal regression passed"

packages/mosaic/framework/tools/git/test-pr-merge-gitea-empty-uid.sh

@@ -51,22 +51,23 @@ for arg in "$@"; do
         prev=""
         continue
     fi
-    if [[ "$prev" == "-d" ]]; then
+    if [[ "$prev" == "data" ]]; then
         post_data="$arg"
+        [[ "$post_data" == @* ]] && post_data=$(<"${post_data#@}")
         prev=""
         continue
     fi
-    if [[ "$arg" == "-o" ]]; then
-        prev="-o"
+    if [[ "$prev" == "config" ]]; then
+        [[ "$arg" == "-" ]] && cat >/dev/null
+        prev=""
         continue
     fi
-    if [[ "$arg" == "-d" ]]; then
-        prev="-d"
-        continue
-    fi
-    if [[ "$arg" == "-w" ]]; then
-        write_code=true
-    fi
+    case "$arg" in
+        -o) prev="-o" ;;
+        -d|--data|--data-binary) prev="data" ;;
+        -K|--config) prev="config" ;;
+        -w) write_code=true ;;
+    esac
 done
 emit_response() {
     local body="$1"

packages/mosaic/framework/tools/git/test-pr-merge-head-pin.sh

@@ -36,13 +36,30 @@ cat > "$WORK_DIR/gitea/curl" <<'SH'
 #!/usr/bin/env bash
 set -euo pipefail
 payload=""
-for ((i=1; i<=$#; i++)); do
-    if [[ "${!i}" == "-d" ]]; then
-        j=$((i + 1))
-        payload="${!j}"
-    fi
+out_file=""
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        -d|--data|--data-binary)
+            payload="$2"
+            [[ "$payload" == @* ]] && payload=$(<"${payload#@}")
+            shift 2
+            ;;
+        -o)
+            out_file="$2"
+            shift 2
+            ;;
+        -K|--config)
+            [[ "$2" == "-" ]] && cat >/dev/null
+            shift 2
+            ;;
+        -w|-X|-H)
+            shift 2
+            ;;
+        *) shift ;;
+    esac
 done
 printf '%s' "$payload" > "${MOSAIC_MERGE_PAYLOAD_LOG:?}"
+[[ -n "$out_file" ]] && printf '{}' > "$out_file"
 printf '200'
 SH
 chmod +x "$WORK_DIR/gitea/curl"

packages/mosaic/framework/tools/git/test-pr-merge-message-field.sh

@@ -0,0 +1,541 @@
+#!/usr/bin/env bash
+# Regression harness for the optional, identity-checked Gitea squash message.
+
+set -u
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SUBJECT="${MOSAIC_TEST_SUBJECT:-$SCRIPT_DIR/pr-merge.sh}"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-merge-message-field}"
+ORIG_PATH="$PATH"
+failures=0
+
+rm -rf "$WORK_DIR"
+mkdir -p "$WORK_DIR"
+
+fail() {
+    echo "FAIL $1" >&2
+    failures=$((failures + 1))
+}
+
+make_case() {
+    local name="$1" case_dir
+    case_dir="$WORK_DIR/$name"
+    mkdir -p "$case_dir/bin" "$case_dir/agent"
+    cp "$SUBJECT" "$case_dir/pr-merge.sh"
+    chmod +x "$case_dir/pr-merge.sh"
+
+    cat > "$case_dir/detect-platform.sh" <<'SH'
+#!/usr/bin/env bash
+detect_platform() { PLATFORM=gitea; printf 'gitea\n'; }
+get_repo_owner() { printf 'acme\n'; }
+get_repo_name() { printf 'widgets\n'; }
+get_remote_host() { printf 'git.example.test\n'; }
+get_gitea_token() {
+    printf 'resolved\n' >> "${MOSAIC_TEST_TOKEN_RESOLUTION_LOG:?}"
+    if [[ "${MOSAIC_TEST_TOKEN_AVAILABLE:-true}" != "true" ]]; then
+        return 1
+    fi
+    printf 'fixture-token\n'
+}
+get_gitea_basic_auth() {
+    printf 'resolved\n' >> "${MOSAIC_TEST_BASIC_RESOLUTION_LOG:?}"
+    if [[ "${MOSAIC_TEST_BASIC_AVAILABLE:-false}" == "true" ]]; then
+        printf 'fixture-user:fixture-password\n'
+        return "${MOSAIC_TEST_BASIC_RC:-0}"
+    fi
+    return 1
+}
+get_gitea_login_for_host() { return 1; }
+SH
+
+    cat > "$case_dir/pr-metadata.sh" <<'SH'
+#!/usr/bin/env bash
+if [[ "${MOSAIC_TEST_TITLE_MODE:-safe}" == "injection" ]]; then
+    title='Preserve authors\n\nCo-authored-by: victim <[email protected]>'
+else
+    title='Preserve both branch authors'
+fi
+case "${MOSAIC_TEST_COMMITS_MODE:?}" in
+    verified) head_sha=2222222222222222222222222222222222222222 ;;
+    null-login|unsafe-identity) head_sha=3333333333333333333333333333333333333333 ;;
+    single) head_sha=1111111111111111111111111111111111111111 ;;
+    *) echo "unknown commits mode" >&2; exit 2 ;;
+esac
+printf '{"number":42,"title":"%s","author":"poster","baseRefName":"main","headRefName":"feature/fixture","headRefOid":"%s","headRepository":"acme/widgets"}\n' "$title" "$head_sha"
+SH
+
+    cat > "$case_dir/ci-queue-wait.sh" <<'SH'
+#!/usr/bin/env bash
+exit 0
+SH
+
+    cat > "$case_dir/bin/python3" <<'SH'
+#!/usr/bin/env bash
+for arg in "$@"; do
+    case "$arg" in
+        *"Preserve both branch authors"*|*"[email protected]"*)
+            : > "${MOSAIC_TEST_METADATA_ARGV_MARKER:?}"
+            ;;
+    esac
+done
+exec "${MOSAIC_TEST_REAL_PYTHON:?}" "$@"
+SH
+
+    cat > "$case_dir/bin/curl" <<'SH'
+#!/usr/bin/env bash
+set -eu
+
+for arg in "$@"; do
+    case "$arg" in
+        *"Preserve both branch authors"*|*"[email protected]"*)
+            : > "${MOSAIC_TEST_METADATA_ARGV_MARKER:?}"
+            ;;
+    esac
+done
+
+url=""
+method="GET"
+out_file=""
+data=""
+config=""
+auth_mode="none"
+has_max_filesize=0
+has_max_time=0
+has_connect_timeout=0
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        -o)
+            out_file="$2"
+            shift 2
+            ;;
+        -w)
+            shift 2
+            ;;
+        -X)
+            method="$2"
+            shift 2
+            ;;
+        -d|--data|--data-binary)
+            data="$2"
+            if [[ "$data" == @* ]]; then
+                data=$(<"${data#@}")
+            fi
+            shift 2
+            ;;
+        -K|--config)
+            if [[ "$2" == "-" ]]; then
+                config=$(cat)
+            fi
+            shift 2
+            ;;
+        --max-filesize)
+            has_max_filesize=1
+            shift 2
+            ;;
+        --max-time)
+            has_max_time=1
+            shift 2
+            ;;
+        --connect-timeout)
+            has_connect_timeout=1
+            shift 2
+            ;;
+        -H|--header|-u|--user)
+            if [[ "$2" == *"fixture-token"* ]]; then
+                : > "${MOSAIC_TEST_TOKEN_ARGV_MARKER:?}"
+            fi
+            if [[ "$2" == *"fixture-password"* ]]; then
+                : > "${MOSAIC_TEST_BASIC_ARGV_MARKER:?}"
+            fi
+            shift 2
+            ;;
+        http://*|https://*)
+            url="$1"
+            shift
+            ;;
+        *)
+            shift
+            ;;
+    esac
+done
+
+if [[ "$config" == *"Authorization: token fixture-token"* ]]; then
+    auth_mode="token"
+    : > "${MOSAIC_TEST_AUTH_CONFIG_MARKER:?}"
+elif [[ "$config" == *"user = \"fixture-user:fixture-password\""* ]]; then
+    auth_mode="basic"
+    : > "${MOSAIC_TEST_BASIC_CONFIG_MARKER:?}"
+fi
+printf '%s %s %s\n' "$method" "$auth_mode" "$url" >> "${MOSAIC_TEST_CURL_LOG:?}"
+printf '%s:%s:%s\n' "$has_max_filesize" "$has_max_time" "$has_connect_timeout" >> "${MOSAIC_TEST_CURL_BOUNDS_LOG:?}"
+
+case "$url" in
+    */pulls/42)
+        case "${MOSAIC_TEST_COMMITS_MODE:?}" in
+            verified) head_sha=2222222222222222222222222222222222222222 ;;
+            null-login|unsafe-identity) head_sha=3333333333333333333333333333333333333333 ;;
+            single) head_sha=1111111111111111111111111111111111111111 ;;
+            *) echo "unknown commits mode" >&2; exit 2 ;;
+        esac
+        if [[ "${MOSAIC_TEST_HEAD_MODE:-stable}" == "moved" ]]; then
+            head_sha=4444444444444444444444444444444444444444
+        fi
+        body="{\"head\":{\"sha\":\"$head_sha\"}}"
+        code=200
+        if [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "inspection" && "$auth_mode" == "token" ]]; then
+            body='{"message":"token rejected"}'
+            code=401
+        fi
+        ;;
+    */pulls/42/commits*)
+        case "${MOSAIC_TEST_COMMITS_MODE:?}" in
+            verified)
+                if [[ "${MOSAIC_TEST_EMAIL_MODE:-safe}" == "escape" ]]; then
+                    body='[{"sha":"2222222222222222222222222222222222222222","commit":{"author":{"name":"Alice","email":"alice+\u001b[[email protected]"}},"author":{"login":"alice"}},{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                else
+                    body='[{"sha":"2222222222222222222222222222222222222222","commit":{"author":{"name":"Alice","email":"[email protected]"}},"author":{"login":"alice"}},{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                fi
+                ;;
+            null-login)
+                body='[{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}},{"sha":"3333333333333333333333333333333333333333","commit":{"author":{"name":"Unresolved Author","email":"[email protected]\n\u001b[31m"}},"author":null}]'
+                ;;
+            unsafe-identity)
+                body='[{"sha":"unsafe\n\u001b[31m","commit":{"author":{"name":"Unsafe","email":"not-an-email"}},"author":{"login":"unsafe"}},{"sha":"3333333333333333333333333333333333333333","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                ;;
+            single)
+                body='[{"sha":"1111111111111111111111111111111111111111","commit":{"author":{"name":"Poster","email":"[email protected]"}},"author":{"login":"poster"}}]'
+                ;;
+            *)
+                echo "unknown commits mode" >&2
+                exit 2
+                ;;
+        esac
+        code=200
+        if [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "inspection" && "$auth_mode" == "token" ]]; then
+            body='{"message":"token rejected"}'
+            code=401
+        fi
+        ;;
+    */pulls/42/merge)
+        body='{}'
+        code=200
+        if [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "merge" && "$auth_mode" == "token" ]]; then
+            body='{"message":"token rejected"}'
+            code=401
+        elif [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "provider-error" ]]; then
+            body='{"message":"branch policy rejected\n\u001b[31m"}'
+            code=409
+        elif [[ "${MOSAIC_TEST_FALLBACK_MODE:-none}" == "forbidden" ]]; then
+            body='{"message":"permission denied"}'
+            code=403
+        else
+            printf '%s' "$data" > "${MOSAIC_TEST_MERGE_PAYLOAD:?}"
+        fi
+        ;;
+    */users/*)
+        body='{"message":"not found"}'
+        code=404
+        ;;
+    *)
+        body='{"message":"unexpected URL"}'
+        code=500
+        ;;
+esac
+
+if [[ -n "$out_file" ]]; then
+    printf '%s' "$body" > "$out_file"
+else
+    printf '%s' "$body"
+fi
+printf '%s' "$code"
+case "${MOSAIC_TEST_CURL_FAILURE:-none}" in
+    oversize) exit 63 ;;
+    stalled) exit 28 ;;
+esac
+SH
+
+    chmod +x "$case_dir/detect-platform.sh" "$case_dir/pr-metadata.sh" \
+        "$case_dir/ci-queue-wait.sh" "$case_dir/bin/curl" "$case_dir/bin/python3"
+    printf '%s\n' "$case_dir"
+}
+
+run_case() {
+    local case_dir="$1" mode="$2"
+    shift 2
+    MOSAIC_TEST_COMMITS_MODE="$mode" \
+    MOSAIC_TEST_CURL_LOG="$case_dir/curl.log" \
+    MOSAIC_TEST_CURL_BOUNDS_LOG="$case_dir/curl-bounds.log" \
+    MOSAIC_TEST_MERGE_PAYLOAD="$case_dir/merge-payload.json" \
+    MOSAIC_TEST_TOKEN_ARGV_MARKER="$case_dir/token-in-argv" \
+    MOSAIC_TEST_BASIC_ARGV_MARKER="$case_dir/basic-in-argv" \
+    MOSAIC_TEST_AUTH_CONFIG_MARKER="$case_dir/auth-via-config" \
+    MOSAIC_TEST_BASIC_CONFIG_MARKER="$case_dir/basic-via-config" \
+    MOSAIC_TEST_TOKEN_RESOLUTION_LOG="$case_dir/token-resolution.log" \
+    MOSAIC_TEST_BASIC_RESOLUTION_LOG="$case_dir/basic-resolution.log" \
+    MOSAIC_TEST_METADATA_ARGV_MARKER="$case_dir/metadata-in-argv" \
+    MOSAIC_TEST_REAL_PYTHON="$(command -v python3)" \
+    AGENT_WORK_ROOT="$case_dir/agent" \
+    PATH="$case_dir/bin:$ORIG_PATH" \
+        "$case_dir/pr-merge.sh" -n 42 "$@"
+}
+
+# Verified multi-author path: the non-poster trailer is built from one commit's
+# linked author.login and that same commit's author email. No /users lookup.
+verified_dir=$(make_case verified)
+set +e
+verified_output=$(run_case "$verified_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+verified_rc=$?
+set -e
+if [[ "$verified_rc" -ne 0 ]]; then
+    fail "verified multi-author merge expected rc=0, got rc=$verified_rc: $verified_output"
+elif [[ ! -s "$verified_dir/merge-payload.json" ]]; then
+    fail "verified multi-author merge did not reach the API payload"
+else
+    python3 - "$verified_dir/merge-payload.json" <<'PY' || fail "verified payload did not preserve squash and exact message fields"
+import json
+import sys
+payload = json.load(open(sys.argv[1], encoding="utf-8"))
+assert payload == {
+    "Do": "squash",
+    "head_commit_id": "2222222222222222222222222222222222222222",
+    "MergeTitleField": "Preserve both branch authors",
+    "MergeMessageField": "Co-authored-by: alice <[email protected]>",
+}, payload
+PY
+fi
+[[ -e "$verified_dir/auth-via-config" ]] || fail "verified path did not authenticate curl through stdin config"
+[[ ! -e "$verified_dir/token-in-argv" ]] || fail "verified path placed the Gitea token in curl argv"
+[[ ! -e "$verified_dir/metadata-in-argv" ]] || fail "verified path placed PR title or contributor email in child argv"
+[[ "$(wc -l < "$verified_dir/token-resolution.log")" -eq 1 ]] || fail "verified path did not bind inspection and merge to one credential resolution"
+if grep -q '/users/' "$verified_dir/curl.log" 2>/dev/null; then
+    fail "verified path performed a forbidden second /users lookup"
+fi
+if grep -qv '^1:1:1$' "$verified_dir/curl-bounds.log"; then
+    fail "verified path did not apply size/max-time/connect-time bounds to every provider download"
+fi
+
+# A linked email containing a terminal escape must block before mutation.
+escape_email_dir=$(make_case escape-email)
+set +e
+escape_email_output=$(MOSAIC_TEST_EMAIL_MODE=escape run_case "$escape_email_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+escape_email_rc=$?
+set -e
+[[ "$escape_email_rc" -ne 0 ]] || fail "control-byte email unexpectedly passed"
+[[ "$escape_email_output" == *"unusable linked identity"* ]] || fail "control-byte email refusal lost its diagnostic"
+[[ ! -e "$escape_email_dir/merge-payload.json" ]] || fail "control-byte email reached the merge API"
+
+# Curl transfer and duration failures must remain failures even with HTTP 200.
+for failure_mode in oversize stalled; do
+    failure_dir=$(make_case "curl-$failure_mode")
+    set +e
+    failure_output=$(MOSAIC_TEST_CURL_FAILURE="$failure_mode" run_case "$failure_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+    failure_rc=$?
+    set -e
+    [[ "$failure_rc" -ne 0 ]] || fail "curl $failure_mode failure was discarded: $failure_output"
+    [[ ! -e "$failure_dir/merge-payload.json" ]] || fail "curl $failure_mode failure reached the merge API"
+done
+
+# The authenticated head is re-read under the mutation credential but cannot
+# replace the canonical preflight/review head. A move blocks before enumeration
+# or mutation even though the provider returned a valid new SHA.
+moved_dir=$(make_case moved-head)
+set +e
+moved_output=$(MOSAIC_TEST_HEAD_MODE=moved \
+    run_case "$moved_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+moved_rc=$?
+set -e
+[[ "$moved_rc" -ne 0 ]] || fail "moved authenticated head unexpectedly passed"
+[[ "$moved_output" == *"authenticated PR head moved from reviewed"* ]] || fail "moved head refusal lost its diagnostic"
+[[ "$moved_output" == *"tl-mosaic"* ]] || fail "moved head refusal omitted the named escalation principal"
+[[ ! -e "$moved_dir/merge-payload.json" ]] || fail "moved head refusal reached the merge API"
+moved_sequence=$(awk '{print $1 ":" $2}' "$moved_dir/curl.log" | paste -sd, -)
+[[ "$moved_sequence" == "GET:token" ]] || fail "moved head refusal performed post-move inspection/mutation (calls=$moved_sequence)"
+
+# Token resolution failure is not an authentication response. It must fail
+# closed instead of borrowing a Basic credential under a different principal.
+token_missing_dir=$(make_case token-missing)
+set +e
+token_missing_output=$(MOSAIC_TEST_TOKEN_AVAILABLE=false MOSAIC_TEST_BASIC_AVAILABLE=true \
+    run_case "$token_missing_dir" single 2>&1)
+token_missing_rc=$?
+set -e
+[[ "$token_missing_rc" -ne 0 ]] || fail "missing token unexpectedly borrowed Basic Auth"
+[[ "$token_missing_output" == *"required Gitea token"* ]] || fail "missing token refusal lost its diagnostic"
+[[ ! -e "$token_missing_dir/basic-resolution.log" ]] || fail "missing token resolved Basic Auth after identity failure"
+[[ ! -e "$token_missing_dir/curl.log" ]] || fail "missing token reached a provider request"
+
+# A failed Basic resolver must never use its nonempty output or reach mutation.
+basic_rc_dir=$(make_case basic-resolver-rc)
+set +e
+basic_rc_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_BASIC_RC=91 MOSAIC_TEST_FALLBACK_MODE=inspection \
+    run_case "$basic_rc_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+basic_rc_rc=$?
+set -e
+[[ "$basic_rc_rc" -ne 0 ]] || fail "failed Basic resolver output unexpectedly authorized a merge: $basic_rc_output"
+[[ ! -e "$basic_rc_dir/merge-payload.json" ]] || fail "failed Basic resolver reached the merge API"
+
+# HTTP 401 never changes principals: inspection rejection fails closed without
+# resolving or attempting Basic Auth.
+fallback_inspect_dir=$(make_case fallback-inspection)
+set +e
+fallback_inspect_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=inspection \
+    run_case "$fallback_inspect_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+fallback_inspect_rc=$?
+set -e
+[[ "$fallback_inspect_rc" -ne 0 ]] || fail "inspection token rejection unexpectedly changed principals"
+[[ "$fallback_inspect_output" == *"refusing cross-principal credential fallback"* ]] || fail "inspection token rejection lost its refusal diagnostic"
+[[ ! -e "$fallback_inspect_dir/basic-resolution.log" ]] || fail "inspection token rejection resolved Basic Auth"
+[[ ! -e "$fallback_inspect_dir/merge-payload.json" ]] || fail "inspection token rejection reached merge mutation"
+inspect_sequence=$(awk '{print $1 ":" $2}' "$fallback_inspect_dir/curl.log" | paste -sd, -)
+[[ "$inspect_sequence" == "GET:token" ]] || fail "inspection rejection made unexpected provider calls (calls=$inspect_sequence)"
+
+# Token rejection at merge likewise fails closed without cross-principal retry.
+fallback_merge_dir=$(make_case fallback-merge)
+set +e
+fallback_merge_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=merge \
+    run_case "$fallback_merge_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+fallback_merge_rc=$?
+set -e
+[[ "$fallback_merge_rc" -ne 0 ]] || fail "merge token rejection unexpectedly changed principals"
+[[ "$fallback_merge_output" == *"refusing cross-principal credential fallback"* ]] || fail "merge token rejection lost its refusal diagnostic"
+[[ ! -e "$fallback_merge_dir/basic-resolution.log" ]] || fail "merge token rejection resolved Basic Auth"
+[[ ! -e "$fallback_merge_dir/merge-payload.json" ]] || fail "merge token rejection recorded a successful payload"
+merge_sequence=$(awk '{print $1 ":" $2}' "$fallback_merge_dir/curl.log" | paste -sd, -)
+[[ "$merge_sequence" == "GET:token,GET:token,POST:token" ]] || fail "merge rejection made unexpected provider calls (calls=$merge_sequence)"
+
+# BLOCK path: a commit email exists but author.login is null. It must name both
+# facts, name the escalation principal, and never reach the merge endpoint.
+null_dir=$(make_case null-login)
+set +e
+null_output=$(run_case "$null_dir" null-login --co-author-trailers --escalate-to tl-mosaic 2>&1)
+null_rc=$?
+set -e
+[[ "$null_rc" -ne 0 ]] || fail "null-login author expected a non-zero BLOCK"
+[[ "$null_output" == *"BLOCK"* ]] || fail "null-login author omitted BLOCK diagnostic"
+[[ "$null_output" == *"author.login=NULL"* ]] || fail "null-login author omitted the null provider fact"
+[[ "$null_output" == *"[email protected]"* ]] || fail "null-login author omitted the commit email fact"
+[[ "$null_output" == *'\n\x1b[31m'* ]] || fail "null-login author diagnostic did not escape control characters"
+[[ "$null_output" != *$'\033'* ]] || fail "null-login author diagnostic emitted a raw terminal escape"
+[[ "$(printf '%s\n' "$null_output" | wc -l)" -eq 1 ]] || fail "null-login author diagnostic permitted newline injection"
+[[ "$null_output" == *"tl-mosaic"* ]] || fail "null-login author omitted the named escalation principal"
+[[ ! -e "$null_dir/merge-payload.json" ]] || fail "null-login BLOCK still reached the merge API"
+
+# Every provider-derived field in alternate BLOCK diagnostics is log-safe too,
+# including an invalid non-head SHA that contains control characters.
+unsafe_dir=$(make_case unsafe-identity)
+set +e
+unsafe_output=$(run_case "$unsafe_dir" unsafe-identity --co-author-trailers --escalate-to tl-mosaic 2>&1)
+unsafe_rc=$?
+set -e
+[[ "$unsafe_rc" -ne 0 ]] || fail "unsafe identity expected a non-zero BLOCK"
+[[ "$unsafe_output" == *"unusable linked identity"* ]] || fail "unsafe identity omitted its BLOCK reason"
+[[ "$unsafe_output" == *'\n\x1b[31m'* ]] || fail "unsafe identity SHA did not escape control characters"
+[[ "$unsafe_output" != *$'\033'* ]] || fail "unsafe identity diagnostic emitted a raw terminal escape"
+[[ "$(printf '%s\n' "$unsafe_output" | wc -l)" -eq 1 ]] || fail "unsafe identity diagnostic permitted newline injection"
+[[ ! -e "$unsafe_dir/merge-payload.json" ]] || fail "unsafe identity BLOCK still reached the merge API"
+
+# The provider PR title cannot add an unchecked trailer outside the constructed
+# message field: multi-line and trailer-shaped titles block before mutation.
+title_dir=$(make_case title-injection)
+set +e
+title_output=$(MOSAIC_TEST_TITLE_MODE=injection \
+    run_case "$title_dir" verified --co-author-trailers --escalate-to tl-mosaic 2>&1)
+title_rc=$?
+set -e
+[[ "$title_rc" -ne 0 ]] || fail "title trailer injection unexpectedly passed"
+[[ "$title_output" == *"not one printable, non-trailer line"* ]] || fail "title injection refusal lost its diagnostic"
+[[ ! -e "$title_dir/merge-payload.json" ]] || fail "title injection reached the merge API"
+
+# Provider failures remain diagnosable after their temporary response file is
+# removed, but provider-controlled control characters stay log-safe.
+error_dir=$(make_case provider-error)
+set +e
+error_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=provider-error \
+    run_case "$error_dir" single 2>&1)
+error_rc=$?
+set -e
+[[ "$error_rc" -ne 0 ]] || fail "provider error unexpectedly passed"
+[[ "$error_output" == *"HTTP 409"* ]] || fail "provider error omitted the HTTP status"
+[[ "$error_output" == *"branch policy rejected"* ]] || fail "provider error response was discarded"
+[[ "$error_output" == *'\n\x1b[31m'* ]] || fail "provider error response did not escape control characters"
+[[ "$error_output" != *$'\033'* ]] || fail "provider error response emitted a raw terminal escape"
+[[ "$error_output" != *"Basic Auth fallback"* ]] || fail "provider error advertised removed Basic Auth fallback"
+[[ ! -e "$error_dir/basic-resolution.log" ]] || fail "HTTP 409 policy denial incorrectly triggered Basic Auth fallback"
+
+# Authorization denials likewise fail closed instead of changing principals.
+forbidden_dir=$(make_case forbidden)
+set +e
+forbidden_output=$(MOSAIC_TEST_BASIC_AVAILABLE=true MOSAIC_TEST_FALLBACK_MODE=forbidden \
+    run_case "$forbidden_dir" single 2>&1)
+forbidden_rc=$?
+set -e
+[[ "$forbidden_rc" -ne 0 ]] || fail "HTTP 403 authorization denial unexpectedly passed"
+[[ "$forbidden_output" == *"HTTP 403"* ]] || fail "authorization denial omitted the HTTP status"
+[[ "$forbidden_output" != *"Basic Auth fallback"* ]] || fail "authorization denial advertised removed Basic Auth fallback"
+[[ ! -e "$forbidden_dir/basic-resolution.log" ]] || fail "HTTP 403 authorization denial incorrectly triggered Basic Auth fallback"
+
+# The BLOCK destination cannot be generic or inferred after failure: opting in
+# without a named principal is refused before any provider operation.
+principal_dir=$(make_case missing-principal)
+set +e
+principal_output=$(run_case "$principal_dir" verified --co-author-trailers 2>&1)
+principal_rc=$?
+set -e
+[[ "$principal_rc" -ne 0 ]] || fail "co-author mode without a named principal unexpectedly passed"
+[[ "$principal_output" == *"requires --escalate-to with a named principal"* ]] || fail "missing-principal refusal lost its diagnostic"
+[[ ! -e "$principal_dir/merge-payload.json" ]] || fail "missing-principal refusal reached the merge API"
+
+# A trailing value-taking option receives a stable CLI diagnostic instead of a
+# set -u unbound-variable crash.
+value_dir=$(make_case missing-principal-value)
+set +e
+value_output=$(run_case "$value_dir" verified --co-author-trailers --escalate-to 2>&1)
+value_rc=$?
+set -e
+[[ "$value_rc" -ne 0 ]] || fail "missing --escalate-to value unexpectedly passed"
+[[ "$value_output" == *"--escalate-to requires one principal name"* ]] || fail "missing --escalate-to value lost its diagnostic"
+[[ "$value_output" != *"unbound variable"* ]] || fail "missing --escalate-to value crashed under set -u"
+[[ ! -e "$value_dir/merge-payload.json" ]] || fail "missing --escalate-to value reached the merge API"
+
+# Negative control: ordinary single-author merge remains byte-for-byte payload
+# compatible and hardcoded to squash, with no optional message fields.
+single_dir=$(make_case single)
+set +e
+single_output=$(run_case "$single_dir" single 2>&1)
+single_rc=$?
+set -e
+if [[ "$single_rc" -ne 0 ]]; then
+    fail "ordinary single-author merge expected rc=0, got rc=$single_rc: $single_output"
+elif [[ ! -s "$single_dir/merge-payload.json" ]]; then
+    fail "ordinary single-author merge did not reach the API payload"
+else
+    python3 - "$single_dir/merge-payload.json" <<'PY' || fail "ordinary single-author payload changed"
+import json
+import sys
+payload = json.load(open(sys.argv[1], encoding="utf-8"))
+assert payload == {
+    "Do": "squash",
+    "head_commit_id": "1111111111111111111111111111111111111111",
+}, payload
+PY
+fi
+[[ -e "$single_dir/auth-via-config" ]] || fail "ordinary path did not authenticate curl through stdin config"
+[[ ! -e "$single_dir/token-in-argv" ]] || fail "ordinary path placed the Gitea token in curl argv"
+[[ "$(wc -l < "$single_dir/token-resolution.log")" -eq 1 ]] || fail "ordinary path did not use exactly one credential resolution"
+
+# Squash is not defaultable: an explicit non-squash method must remain refused.
+method_dir=$(make_case method-refusal)
+set +e
+method_output=$(run_case "$method_dir" single -m merge 2>&1)
+method_rc=$?
+set -e
+[[ "$method_rc" -ne 0 ]] || fail "non-squash method unexpectedly passed"
+[[ "$method_output" == *"enforces squash merge only"* ]] || fail "non-squash refusal lost its policy diagnostic"
+[[ ! -e "$method_dir/merge-payload.json" ]] || fail "non-squash refusal reached the merge API"
+
+if [[ "$failures" -ne 0 ]]; then
+    echo "pr-merge message-field regression failed ($failures assertions)" >&2
+    exit 1
+fi
+
+echo "pr-merge message-field regression passed (verified, BLOCK, and unchanged squash control)"

packages/mosaic/framework/tools/quality/scripts/test-upgrade-rollback.sh

@@ -39,11 +39,12 @@ ORIG_PATH="$PATH"
 # loop — which would make the control a false negative. A root dotfile is
 # operator-owned (unknown→operator), so the sync loop skips it. Clean up on exit.
 STRIPPED="$FW/.install-rollback-control.tmp.sh"
+SIGNALED="$FW/.install-signal-control.tmp.sh"
 NOEXIT="$FW/.install-noexit-control.tmp.sh"
 D1CTRL="$FW/.install-d1guard-control.tmp.sh"
 D2CTRL="$FW/.install-d2guard-control.tmp.sh"
-rm -f "$STRIPPED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
-trap 'rm -f "$STRIPPED" "$NOEXIT" "$D1CTRL" "$D2CTRL"' EXIT
+rm -f "$STRIPPED" "$SIGNALED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
+trap 'rm -f "$STRIPPED" "$SIGNALED" "$NOEXIT" "$D1CTRL" "$D2CTRL"' EXIT
 
 pass=0; fail=0
 chk() { if eval "$2"; then echo "  ✓ $1"; pass=$((pass + 1)); else echo "  ✗ $1"; fail=$((fail + 1)); fi; }
@@ -180,41 +181,86 @@ chk "[control] without -E the mid-sync corruption survives (no rollback)" \
 # ── Part C: an INT/TERM interrupt must terminate, not resume (blocker-A) ──────
 # A bash signal trap that merely returns lets the script continue past the
 # interrupt — restoring the snapshot, then resuming the sync and reporting
-# success. We inject a SIGTERM mid-sync with a cp that SUCCEEDS (so set -e never
-# fires and ONLY the signal path governs), and assert the shipped installer
-# restores AND exits without reporting success. The control strips `exit 1` from
-# the trap and shows the buggy resume-to-success.
-make_term_shim() {
-  local dir="$1"
-  cat > "$dir/cp" <<SHIM
-#!/usr/bin/env bash
-dest="\${@: -1}"
-case "\$dest" in
-  */$POISON_REL)
-    kill -TERM "\$PPID" 2>/dev/null   # signal install.sh; the copy still succeeds
-    exec env PATH="$ORIG_PATH" cp "\$@" ;;
-esac
-exec env PATH="$ORIG_PATH" cp "\$@"
-SHIM
-  chmod +x "$dir/cp"
+# success. The earlier test used a child cp shim to signal its parent, making
+# child completion race Bash's interrupted wait. Concurrency is not part of the
+# guarded property: sync_framework_keep() runs in the installer's own Bash
+# process, and `kill` is a builtin. Generate two installer fixtures that signal
+# themselves at the same known mid-sync point. Their TERM handlers emit the same
+# observable before diverging, so missing signal delivery fails BOTH arms rather
+# than manufacturing a pass. The only semantic difference between fixtures is
+# the explicit `exit 1` whose load-bearing behavior this control proves.
+TERM_MARKER='[test-control] TERM handler entered'
+HANDLER_WITH_EXIT="trap 'echo \"$TERM_MARKER\" >&2; restore_snapshot; exit 1' TERM  # TEST-TERM-HANDLER"
+HANDLER_WITHOUT_EXIT="trap 'echo \"$TERM_MARKER\" >&2; restore_snapshot' TERM  # TEST-TERM-HANDLER"
+
+make_signal_installer() {
+  local output="$1" handler="$2"
+  local target_trap="trap 'restore_snapshot; exit 1' ERR INT TERM"
+  local target_cp='    cp "$abs" "$dst/$rel"'
+  local inject_open="    if [[ \"\$rel\" == \"$POISON_REL\" ]]; then"
+  local inject_kill='      kill -TERM "$$"  # TEST-TERM-INJECTION'
+  local inject_close='    fi'
+
+  if ! awk \
+    -v target_trap="$target_trap" -v target_cp="$target_cp" \
+    -v handler="$handler" -v inject_open="$inject_open" \
+    -v inject_kill="$inject_kill" -v inject_close="$inject_close" '
+      $0 == target_cp {
+        print inject_open
+        print inject_kill
+        print inject_close
+        injection_sites++
+      }
+      { print }
+      $0 == target_trap {
+        print handler
+        handler_sites++
+      }
+      END {
+        if (handler_sites != 1 || injection_sites != 1) exit 42
+      }
+    ' "$INSTALL" > "$output"; then
+    rm -f "$output"
+    fail "Could not construct the self-TERM control installer at the exact trap/copy sites"
+    exit 1
+  fi
+  chmod +x "$output"
 }
 
-# Run one keep-mode upgrade with the SIGTERM shim. Echoes "<exit>\t<out>\t<home>".
+make_signal_installer "$SIGNALED" "$HANDLER_WITH_EXIT"
+make_signal_installer "$NOEXIT" "$HANDLER_WITHOUT_EXIT"
+signal_fixture_ready() {
+  local fixture="$1" expected_handler="$2"
+  [[ "$(grep -cF '# TEST-TERM-INJECTION' "$fixture")" -eq 1 ]] \
+    && [[ "$(grep -cF '# TEST-TERM-HANDLER' "$fixture")" -eq 1 ]] \
+    && grep -Fqx "$expected_handler" "$fixture"
+}
+signaled_fixture_ready() { signal_fixture_ready "$SIGNALED" "$HANDLER_WITH_EXIT"; }
+noexit_fixture_ready() { signal_fixture_ready "$NOEXIT" "$HANDLER_WITHOUT_EXIT"; }
+chk "[signal] shipped fixture has exactly one self-TERM injection and marked handler" \
+  "signaled_fixture_ready"
+chk "[control] no-exit fixture has exactly one self-TERM injection and marked handler" \
+  "noexit_fixture_ready"
+chk "[control] removing the explicit TERM exit changes the fixture" \
+  "! cmp -s '$SIGNALED' '$NOEXIT'"
+
+# Run one keep-mode upgrade whose own shell delivers SIGTERM synchronously at
+# the selected copy. Echoes "<exit>\t<out>\t<home>".
 run_signal_upgrade() {
-  local installer="$1" H OUT SHIM rc
-  H=$(mktemp -d); OUT=$(mktemp); SHIM=$(mktemp -d)
+  local installer="$1" H OUT rc
+  H=$(mktemp -d); OUT=$(mktemp)
   seed_home "$H"
-  make_term_shim "$SHIM"
   set +e
-  PATH="$SHIM:$ORIG_PATH" \
+  PATH="$ORIG_PATH" \
     MOSAIC_HOME="$H" MOSAIC_INSTALL_MODE=keep MOSAIC_SYNC_ONLY=1 bash "$installer" >"$OUT" 2>&1
   rc=$?
   set -e 2>/dev/null || true
-  rm -rf "$SHIM"
   printf '%s\t%s\t%s\n' "$rc" "$OUT" "$H"
 }
 
-IFS=$'\t' read -r rcC OUTC HC < <(run_signal_upgrade "$INSTALL")
+IFS=$'\t' read -r rcC OUTC HC < <(run_signal_upgrade "$SIGNALED")
+chk "[signal] TERM handler observable fires exactly once" \
+  "[ \"\$(grep -cF '$TERM_MARKER' '$OUTC')\" -eq 1 ]"
 chk "[signal] SIGTERM mid-sync aborts non-zero (trap exits, does not resume)" \
   "[ '$rcC' -ne 0 ]"
 chk "[signal] restore_snapshot fires on the interrupt" \
@@ -222,13 +268,13 @@ chk "[signal] restore_snapshot fires on the interrupt" \
 chk "[signal] does NOT resume to report sync success after the interrupt" \
   "! grep -q 'file phase complete' '$OUTC'"
 
-# Control: strip `exit 1` from the signal trap → the handler returns, the script
-# resumes past the interrupt and wrongly reports success. In $FW so SOURCE_DIR resolves.
-sed "s/trap 'restore_snapshot; exit 1' ERR INT TERM/trap 'restore_snapshot' ERR INT TERM/" \
-  "$INSTALL" > "$NOEXIT"
-chk "[control] the exit-strip actually changed the installer" \
-  "! cmp -s '$INSTALL' '$NOEXIT'"
-IFS=$'\t' read -r _rcD OUTD HD < <(run_signal_upgrade "$NOEXIT")
+IFS=$'\t' read -r rcD OUTD HD < <(run_signal_upgrade "$NOEXIT")
+chk "[control] TERM handler observable fires exactly once" \
+  "[ \"\$(grep -cF '$TERM_MARKER' '$OUTD')\" -eq 1 ]"
+chk "[control] without 'exit 1' the handler restores before returning" \
+  "grep -q 'restoring previous state from snapshot' '$OUTD'"
+chk "[control] without 'exit 1' the installer exits zero after resuming" \
+  "[ '$rcD' -eq 0 ]"
 chk "[control] without 'exit 1' the trap resumes and reports sync success (the bug)" \
   "grep -q 'file phase complete' '$OUTD'"
 
@@ -309,10 +355,10 @@ chk "[control] without the D2 recovery line the operator gets no snapshot pointe
 # Reap any snapshot the reset-fail runs left in /tmp (reset failed → never cleaned).
 grep -o '/[^ ]*mosaic-snapshot[^ ]*' "$OUTH" 2>/dev/null | head -1 | while read -r s; do rm -rf "$s"; done
 
-# Cleanup ($STRIPPED / $NOEXIT / $D1CTRL / $D2CTRL are also removed by the EXIT trap).
+# Cleanup (generated installer controls are also removed by the EXIT trap).
 for d in "$HA" "$REFA" "$HB" "$REFB" "$HC" "$HD" "$HE" "$REFE" "$HF" "$REFF" "$HG" "$HH"; do rm -rf "$d"; done
 rm -f "$OUTA" "$OUTB" "$OUTC" "$OUTD" "$OUTE" "$OUTF" "$OUTG" "$OUTH" \
-  "$STRIPPED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
+  "$STRIPPED" "$SIGNALED" "$NOEXIT" "$D1CTRL" "$D2CTRL"
 
 echo
 echo "RESULT: $pass passed, $fail failed"

packages/mosaic/package.json

@@ -25,7 +25,7 @@
     "lint": "eslint src",
     "typecheck": "tsc --noEmit",
     "test": "vitest run --passWithNoTests && pnpm run test:framework-shell",
-    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
+    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-pr-merge-message-field.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/git/test-explain-diagnostic-status-neutral.sh && bash framework/tools/git/test-detect-platform-outside-repo.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
   },
   "dependencies": {
     "@mosaicstack/brain": "workspace:*",