fix(git-tools): refuse no-ci assertion without an attributable identity

The --no-ci-expected admin-success path accepted an asserted-by=unknown
pass when MOSAIC_GIT_IDENTITY was unset or empty, so the queue-clear
assertion and its NO_CI_ASSERTED audit record named no one. Refuse such
callers with a distinct ASSERTION_UNATTRIBUTABLE outcome (exit 78, audit
recorded) before queue-clear and before the permission lookup, so an
unattributable caller never triggers that network call. Document exit 78
in the usage text and the tools reference; pin the path with a
regression case (admin stub + env -u MOSAIC_GIT_IDENTITY).

packages/mosaic/framework/guides/TOOLS-REFERENCE.md

@@ -111,7 +111,7 @@ approve path carries the trap.) `pr-review.sh` sends the correct token for the d
 Whatever you use, re-read `GET /pulls/{n}/reviews` and assert the state before reporting a verdict
 placed.
 
-The guard exits nonzero for any provider-asserted non-green, missing, or malformed CI state. If credentials or the provider are unavailable, it emits `CANNOT_ASSERT` and writes a JSONL audit record. Push degrades to exit 0 so recovery work is not bricked; merge holds with retryable exit 75 until the provider recovers, then self-clears without manual reset. Neither outcome is evidence that CI was clear. For a repository with no CI configured at all, `pr-merge.sh --no-ci-expected` is the sanctioned merge path: it forwards to `ci-queue-wait.sh --no-ci-expected`, which reclassifies a zero-context merge head as queue-clear only when the acting token holds repository admin, and records the assertion (or its refusal) in the same JSONL audit log. `pr-merge.sh` automatically inspects the exact PR head repository and full commit SHA rather than its `main` base; this also handles fork PRs without branch-name ambiguity. Pass `--expect-head <approved-full-sha>` to bind a commit-specific review or merge-gate verdict; Gitea uses atomic `head_commit_id` and GitHub uses `--match-head-commit`.
+The guard exits nonzero for any provider-asserted non-green, missing, or malformed CI state. If credentials or the provider are unavailable, it emits `CANNOT_ASSERT` and writes a JSONL audit record. Push degrades to exit 0 so recovery work is not bricked; merge holds with retryable exit 75 until the provider recovers, then self-clears without manual reset. Neither outcome is evidence that CI was clear. For a repository with no CI configured at all, `pr-merge.sh --no-ci-expected` is the sanctioned merge path: it forwards to `ci-queue-wait.sh --no-ci-expected`, which reclassifies a zero-context merge head as queue-clear only when the acting token holds repository admin and `MOSAIC_GIT_IDENTITY` names the asserting identity (a caller without one is refused with exit 78 before the admin lookup), and records the assertion (or its refusal) in the same JSONL audit log. `pr-merge.sh` automatically inspects the exact PR head repository and full commit SHA rather than its `main` base; this also handles fork PRs without branch-name ambiguity. Pass `--expect-head <approved-full-sha>` to bind a commit-specific review or merge-gate verdict; Gitea uses atomic `head_commit_id` and GitHub uses `--match-head-commit`.
 
 ### Code Review (Codex)
 

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

@@ -28,7 +28,7 @@ Options:
   -i, --interval SECONDS   Poll interval in seconds (default: 15)
       --purpose VALUE      Log context: push|merge (default: merge)
       --require-status     Fail if no CI status contexts are present
-      --no-ci-expected     Assert this repository has no CI configured: a merge guard on a zero-context head becomes queue-clear (requires the acting token to hold repository admin)
+      --no-ci-expected     Assert this repository has no CI configured: a merge guard on a zero-context head becomes queue-clear (requires the acting token to hold repository admin); refused with exit 78 when MOSAIC_GIT_IDENTITY is unset or empty
   -h, --help               Show this help
 
 Examples:
@@ -597,7 +597,18 @@ while true; do
                 # the ONLY state the flag reclassifies: a pending or failed
                 # context still holds or fails exactly as without it, and a
                 # non-admin token is refused rather than trusted.
-                ASSERTED_BY="${MOSAIC_GIT_IDENTITY:-unknown}"
+                # The assertion must name an asserting identity: "unknown"
+                # attributes nothing, so a caller with MOSAIC_GIT_IDENTITY
+                # unset or empty is refused (exit 78) BEFORE the permission
+                # lookup -- an unattributable caller never triggers that
+                # network call.
+                if [[ -z "${MOSAIC_GIT_IDENTITY:-}" ]]; then
+                    record_assertion_event "ASSERTION_UNATTRIBUTABLE" "actor-unattributable" "unknown" \
+                        || echo "Warning: could not write the ASSERTION_UNATTRIBUTABLE audit record; the refusal itself stands." >&2
+                    echo "Error: ASSERTION_UNATTRIBUTABLE state=no-status purpose=merge asserted-by=unknown reason=no-ci-expected branch=${BRANCH}; --no-ci-expected requires MOSAIC_GIT_IDENTITY to name the asserting identity and it is unset or empty (exit 78)." >&2
+                    exit 78
+                fi
+                ASSERTED_BY="${MOSAIC_GIT_IDENTITY}"
                 ADMIN_STATE=2
                 if [[ "$PLATFORM" == "github" ]]; then
                     if github_repo_admin_state "$OWNER" "$REPO"; then ADMIN_STATE=0; else ADMIN_STATE=$?; fi

packages/mosaic/framework/tools/git/test-ci-queue-wait-no-ci-expected.sh

@@ -19,6 +19,9 @@
 #       unchanged; no admin consultation on push.
 #   (g) flag + admin lookup unreachable      -> CANNOT_ASSERT hold (75),
 #       not a silent pass and not a refusal.
+#   (h) flag + admin stub + NO MOSAIC_GIT_IDENTITY -> refusal BEFORE
+#       queue-clear and BEFORE the admin lookup: exit 78, no queue-clear
+#       line, an ASSERTION_UNATTRIBUTABLE JSONL record, no repos/ call.
 
 set -u
 
@@ -111,6 +114,25 @@ run_guard() {
     )
 }
 
+# The suite exports test-identity globally, so the unattributable-caller
+# case must strip it from the child environment at invocation with env -u,
+# not rely on the export order.
+run_guard_no_identity() {
+    local name="$1"; shift
+    (
+        cd "$REPO_DIR" || exit
+        export PATH="$STUB_DIR:$PATH"
+        export MOSAIC_CREDENTIALS_FILE="$WORK_DIR/no-credentials.json"
+        export MOSAIC_CI_QUEUE_AUDIT_LOG="$WORK_DIR/audit-$name.jsonl"
+        export MOSAIC_STUB_URL_LOG="$URL_LOG"
+        export GITEA_TOKEN="stub-token"
+        export GITEA_URL="https://git.example.test"
+        export MOSAIC_GIT_IDENTITY="test-identity"
+        env -u MOSAIC_GIT_IDENTITY \
+            "$SCRIPT_DIR/ci-queue-wait.sh" -B main -t 3 -i 1 "$@"
+    )
+}
+
 expect_rc() {
     local name="$1" want="$2" got="$3"
     if [[ "$want" == "not3" ]]; then
@@ -272,6 +294,27 @@ if ! grep -q '"outcome":"CANNOT_ASSERT"' "$WORK_DIR/audit-g.jsonl" 2>/dev/null;
     failures=$((failures + 1))
 fi
 
+# (h) flag + admin stub + no asserting identity -> refusal before queue-clear
+# and before the admin lookup: rc 78, no queue-clear line, an
+# ASSERTION_UNATTRIBUTABLE JSONL record, and zero repos/ network calls.
+: > "$URL_LOG"
+set +e
+out_h=$(MOSAIC_STUB_STATUS_MODE=no-status MOSAIC_STUB_ADMIN_MODE=admin run_guard_no_identity h --purpose merge --no-ci-expected 2>&1)
+rc_h=$?
+set -u
+if expect_rc h 78 "$rc_h"; then
+    expect_text h "ASSERTION_UNATTRIBUTABLE state=no-status purpose=merge asserted-by=unknown reason=no-ci-expected branch=main" "$out_h"
+    expect_text h "queue-clear" "$out_h" absent
+    if ! grep -q '"outcome":"ASSERTION_UNATTRIBUTABLE"' "$WORK_DIR/audit-h.jsonl" 2>/dev/null; then
+        echo "FAIL h: expected an ASSERTION_UNATTRIBUTABLE JSONL audit record" >&2
+        failures=$((failures + 1))
+    fi
+fi
+if repo_root_fetched; then
+    echo "FAIL h: an unattributable caller must not trigger the permission lookup" >&2
+    failures=$((failures + 1))
+fi
+
 if [[ "$failures" -ne 0 ]]; then
     echo "ci-queue-wait no-ci-expected regression failed ($failures assertions)" >&2
     exit 1