fix(effort): harden lib/effort-pins.sh (security gate, 4 LOW)

Last map line without newline read; unclosed frontmatter skipped with an
err; level re-read after write, mismatch counted as failed; mktemp + cp -p
+ mv, temp removed on failure; rc 1 on any rejected or failed entry.
Cases T11-T14 in the fixture suite; contract criteria 8-9.

.claude/tasks/contracts/2026-09-29-effort-round-1315.md

@@ -12,6 +12,7 @@
 - Defect found in passing, fixed here: `update-all.sh` re-fetched the vendored skills but never re-applied the pins (lost until the next `make plugin`).
 - Defect found in passing, surfaced not fixed: ~94 % of sub-agent usage records carry no `output_tokens_details`, so `lib/effort-audit.py` read zero thinking on sub-agents; the script now prints coverage and a CAVEAT; EVAL-037's "executors stay cheap" is a measurement gap (registry correction pending user approval).
 - lib/tests/effort-routing.test.sh line 4 widens its shellcheck directive from SC2015 to SC2015,SC2016: the new `has … '$REPO'` locks are literal source text, the `$REPO` must NOT expand (authorized; a test file, informational). [verifier 2026-09-29 gap 3]
+- Hardening round (criteria 8-9) added after the security gate on user go; the fixture suite may `chmod` its own mktemp directory (555 then back to 755 for the trap cleanup), never `-R`, never outside the fixture.
 - Frontmatter placement of the inserted `effort:` line (after `name:`, else before the closing `---`) has no harness effect; locked by the fixture suite only.
 
 ## ACCEPTANCE CRITERIA
@@ -44,6 +45,15 @@
    EXPECT: LINT_OK
    EVIDENCE: MET exit=0 marker-found :: LINT_OK
 
+8. Hardening (security gate 2026-09-29, 4 LOW, user go): (a) a map whose last line has no trailing newline still applies that line; (b) a SKILL.md whose frontmatter has no closing `---` is skipped with an err line, file byte-identical; (c) a CRLF SKILL.md (`---\r`) is never counted as applied: the helper re-reads the level after the write and reports a mismatch as err, counted as failed (rc 1); (d) a write failure (read-only skill directory) is reported as err, counted as failed, and leaves no temporary file behind. Cases T11-T14 in lib/tests/effort-pins.test.sh, header comment of the helper updated.
+   CHECK: out=$(make test suite=lib/tests/effort-pins.test.sh 2>&1); echo "$out" | grep -q 'effort-pins: [0-9]* pass, 0 fail' || { echo "$out" | grep FAIL; exit 1; }; for k in T11-last-line-no-newline T12-unterminated-frontmatter-skipped T13-crlf-not-counted-applied T14-write-failure-no-temp; do echo "$out" | grep -q "PASS $k" || { echo "missing PASS $k"; exit 1; }; done; echo HARDEN_GREEN
+   EXPECT: HARDEN_GREEN
+   EVIDENCE: MET exit=0 marker-found :: HARDEN_GREEN
+9. Hardening keeps everything else green: shellcheck clean on the helper and its suite, effort-routing census green, live tree still idempotent (0 applied).
+   CHECK: shellcheck lib/effort-pins.sh lib/tests/effort-pins.test.sh && make test suite=lib/tests/effort-routing.test.sh 2>&1 | grep -q 'census: [0-9]* pass, 0 fail' && bash lib/effort-pins.sh 2>&1 | grep -q ' 0 applied, [0-9]* already at level' && echo HARDEN_STABLE
+   EXPECT: HARDEN_STABLE
+   EVIDENCE: MET exit=0 marker-found :: HARDEN_STABLE
+
 ## FILE SCOPE
 - lib/effort-pins.txt, lib/effort-pins.sh (new); lib/tests/effort-pins.test.sh (new); lib/tests/effort-routing.test.sh
 - install-plugins.sh, update-all.sh (re-apply call), lib/effort-audit.py (coverage)