fix(implement-loop): no-op-repair backstop is severity-aware

The fingerprint early-exit closed a task DONE-with-concerns on a
byte-identical repair diff regardless of severity — a real defect the
opus review flagged as important could ride a green commit as a mere
concern (pipeline-audit finding). The exit now checks the surviving
finding set: any important finding over an unchanged diff is BLOCKED
(reason names it, detail carries the findings); minor-only or
unreported sets keep the existing neutral hold for the orchestrator's
Step-3 adjudication.

refs #29

implement/workflows/implement-loop.js

@@ -40,9 +40,12 @@
 //     task prescribes) is HELD, not chased into a deviation the next review
 //     then re-flags. The repair implementer keeps the plan and records the
 //     finding in `held`; a no-op backstop holds it anyway when a repair
-//     leaves the diff unchanged (or cycles back) yet quality still flags.
-//     Either way the finding surfaces as a concern, not a false BLOCKED on a
-//     green task — and the orchestrator weighs it on its Step-3 inspection.
+//     leaves the diff unchanged (or cycles back) yet quality still flags —
+//     severity-aware (issue #29): a surviving IMPORTANT finding over a
+//     byte-identical repair diff is BLOCKED, never a held concern; only
+//     minor-only residue rides as a concern.
+//     Either way a held finding surfaces as a concern, not a false BLOCKED on
+//     a green task — and the orchestrator weighs it on its Step-3 inspection.
 //     A finding the implementer judges correctness-breaking (would not
 //     build / a test fails / a prescribed caller breaks) escalates to
 //     BLOCKED instead of holding. The held/no-op partition is the
@@ -684,10 +687,24 @@ async function runTask(task) {
     // No-op / cyclic-repair backstop: a changes_requested verdict over a diff-state already reviewed-and-flagged
     // this task means the intervening repair changed nothing (or cycled back to an earlier state) — the
     // implementer kept the plan, or rejected the finding. Re-running quality would only re-flag identical code,
-    // so stop here rather than burning the retry budget down to a false BLOCKED. A byte-identical diff cannot
-    // distinguish a principled plan-hold from an ignored finding, so the concern is labelled neutrally and left
-    // for the orchestrator to adjudicate on its Step-3 inspection.
+    // so stop here rather than burning the retry budget down to a false BLOCKED.
+    // Severity check (issue #29, from the pipeline audit): the early exit is severity-aware. A byte-identical
+    // diff under a surviving IMPORTANT finding is not a cosmetic hold — an important finding names a defect the
+    // repair did not address, and letting it ride a green commit as a mere concern is exactly the erosion this
+    // gate exists to stop → BLOCKED. Only a minor-only (or unreported) finding set is held as a neutral concern:
+    // a byte-identical diff cannot distinguish a principled plan-hold from an ignored cosmetic finding, so that
+    // case is labelled neutrally and left for the orchestrator to adjudicate on its Step-3 inspection.
     if (qual && qual.status === 'changes_requested' && qual.diff_fingerprint && seenFingerprints.has(qual.diff_fingerprint)) {
+      const importants = (qual.issues || []).filter((i) => i.severity === 'important')
+      if (importants.length) {
+        return {
+          id: task.id,
+          title: task.title,
+          outcome: 'BLOCKED',
+          reason: 'unresolved important quality finding — the repair left the diff unchanged',
+          detail: importants.map((i) => i.text).join('; '),
+        }
+      }
       heldConcerns = (qual.issues && qual.issues.length ? qual.issues.map((i) => `${i.severity}: ${i.text}`) : ['(finding not reported)']).map(
         (i) =>
           'unresolved quality finding — the repair left the diff unchanged (a kept plan-prescribed element, or a ' +