feat(retro,preamble): gstack-shortcut debt ledger — accepted shortcuts leave a joined trail

When the user accepts an option that is BOTH Completeness <= 7 AND a
durable-scope call, the decision ledger entry (gstack-decision-log, ceiling +
upgrade trigger in the rationale) is the source of truth, and the agent marks
each cut corner in code with gstack-shortcut(dec-<id>): <ceiling>, upgrade
when <trigger> — same edit, no follow-up question, never agent-initiated.

/retro Step 11.5 harvests markers into a debt ledger (grep || true — zero
matches is the healthy case; skill installs and docs excluded), joins on the
decision id so nothing double-counts, tags unlinked and no-trigger rot risks,
and closes with 'N markers, M with no trigger.'

/review suppressions: a marker with ceiling+trigger downgrades a would-be
Completeness Gaps finding to acknowledged debt. Redaction test pins that the
marker ships untouched (the ledger is the point) — it does not match the
TODO(owner) hygiene shape.

Format from dietrichgebert/ponytail's ponytail-debt; store inverted to gstack's
existing decision ledger.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/redact-engine.test.ts

@@ -380,6 +380,15 @@ describe("LOW patterns surface only", () => {
     );
     expect(f?.tier).toBe("LOW");
   });
+  test("gstack-shortcut(dec-*) debt marker survives redaction untouched", () => {
+    // The shortcut ledger convention (AskUserQuestion Format / /retro Step 11.5)
+    // ships in commits and PR bodies BY DESIGN — the ledger is the point. It
+    // must not be caught by hygiene.todo's TODO(owner) shape or anything else.
+    const marker =
+      "// gstack-shortcut(dec-a1b2c3): global lock, upgrade when throughput matters";
+    const result = scan(marker, { repoVisibility: "public" });
+    expect(result.findings).toHaveLength(0);
+  });
 });
 
 describe("placeholder suppression (per-span)", () => {