evals: Opus pin on the spec AUQ-matrix entry — D1a regressor, receipts in-file

The periodic re-baseline for the capture default (Opus -> Sonnet)
found exactly one regressor across the seven-entry AUQ behavioral
matrix: spec failed twice under Sonnet ('never reached a question in
budget', 242s) while its six siblings passed; the controlled Opus
re-run passed cleanly (7/7 format, substance 5, 160s), and a second
run through the new per-entry model plumbing confirms. MatrixSkill
gains an optional model field wired into captureFirstAuq; only spec
sets it. TODOS gains the re-baseline receipts for the never-baselined
periodic tail (three setup-gbrain files + ship-idempotency, all
local-only).

test/skill-e2e-auq-matrix.test.ts

@@ -67,6 +67,8 @@ interface MatrixSkill {
   skill: string;
   fixtures: Record<string, string>;
   scenario: string;
+  /** D1a regressor pin: explicit capture model when the Sonnet default measurably fails this entry. */
+  model?: string;
 }
 
 const MATRIX: MatrixSkill[] = [
@@ -99,6 +101,13 @@ const MATRIX: MatrixSkill[] = [
     skill: 'spec',
     fixtures: {},
     scenario: 'Turn this vague intent into a precise spec: "add email notifications when a task is assigned to someone." Walk the spec workflow until the first AskUserQuestion.',
+    // D1a pin-on-regressors, with receipts (2026-08-16 re-baseline): under
+    // the Sonnet capture default this entry failed twice ("never reached a
+    // question in budget", 242s) while the six sibling entries passed; the
+    // controlled Opus re-run passed cleanly (7/7 format, substance 5, 160s).
+    // The spec workflow's long pre-question phase needs the stronger model
+    // to reach its first AskUserQuestion inside the turn budget.
+    model: 'claude-opus-4-7',
   },
   {
     skill: 'design-consultation',
@@ -130,6 +139,7 @@ describeE2E('AUQ behavioral matrix (periodic)', () => {
             scenario: m.scenario,
             testName: `auq-matrix-${m.skill}`,
             runId,
+            model: m.model,
           });
         } finally {
           fs.rmSync(dir, { recursive: true, force: true });