fix(sse): drain new-base reds surfaced on the merged tip (#11178, #11238, #11267)

Three reds the PR's CI surfaced after the base advanced past the branch
cut — each discriminated with its origin PR:

1. chatcore-translation-paths 'Combo skip behavior' (shard 3/4) — REAL
   BUG in #11178: the incompatible-reasoning action derivation switched
   from the explicit fallback config to isComboStep =
   Boolean(comboStepId || comboExecutionKey). Combos whose records carry
   no explicit stepId/executionKey (plain model-list combos) had their
   explicit reasoningTransportFallback: 'skip' config silently degraded
   to 'drop', contradicting the PR's own stated intent ('combos keep
   their explicit strategy'). Fix: isComboStep now honors the isCombo
   marker (isCombo || step ids present). RED->GREEN on the exact CI
   failing test; the #10959 single-target drop defaults stay green.

2. check-db-rules-classification 'recovery zero importers' (shard 1/4)
   — STALE GATE, not dead code: #11238 converted bin/cli/runtime.mjs
   dynamic imports to the Windows-safe projectFileUrl('...') idiom, and
   the gate's importer regexes only recognized static/from/template
   import forms. recovery's only importer became invisible. Fix: gate
   pattern set extended to recognize import(projectFileUrl('…/db/<mod>.ts')).

3. mutation-test-coverage gate — #11267 added
   tests/unit/quota-exhaustion-cutoff-opencode.test.ts covering
   src/sse/services/auth.ts without registering it in stryker.conf.json
   tap.testFiles. Fix: register it (gate green locally).

Refs #9985

open-sse/handlers/chatCore.ts

@@ -1218,7 +1218,12 @@ export async function handleChatCore({
           credentials?.providerSpecificData?.preserveEncryptedReasoning === true,
         onIncompatibleReasoning: resolveIncompatibleReasoningAction({
           reasoningTransportFallback,
-          isComboStep: Boolean(comboStepId || comboExecutionKey),
+          // #11178 regressed combo steps whose combo record carries no explicit
+          // stepId/executionKey (plain model-list combos): their explicit
+          // `reasoningTransportFallback: "skip"` config was silently degraded to
+          // "drop". `isCombo` is the combo marker; step ids are optional
+          // finer-grained metadata that plain combos never set.
+          isComboStep: Boolean(isCombo) || Boolean(comboStepId || comboExecutionKey),
           headers: clientRawRequest?.headers ?? null,
         }),
       }

stryker.conf.json

@@ -307,6 +307,7 @@
       "tests/unit/public-client-ids-3493.test.ts",
       "tests/unit/publicCreds.test.ts",
       "tests/unit/qoder-oauth-config.test.ts",
+      "tests/unit/quota-exhaustion-cutoff-opencode.test.ts",
       "tests/unit/quota-groups-route.test.ts",
       "tests/unit/quota-key-models-route.test.ts",
       "tests/unit/quota-policy-generalization.test.ts",

tests/unit/check-db-rules-classification.test.ts

@@ -61,6 +61,11 @@ function hasImporter(mod: string, roots: string[]): boolean {
     new RegExp(`(?:import|require)\\s*\\(\\s*['""][^'"]+/db/${escaped}['"]`),
     // dynamic template: import(`…/db/<mod>.ts`) — bin/cli/runtime.mjs uses template literals
     new RegExp(`import\\s*\\(\`[^'"\`]+/db/${escaped}\\.ts\`\\)`),
+    // dynamic via file:// URL helper: import(projectFileUrl("…/db/<mod>.ts")) —
+    // bin/cli/runtime.mjs since #11238 (Windows-safe file:// dynamic imports).
+    new RegExp(
+      `import\\s*\\(\\s*projectFileUrl\\(\\s*['""][^'"]+/db/${escaped}\\.ts['"]\\s*\\)\\s*\\)`
+    ),
     // relative import within db/: from "./<mod>" or from "./<mod>"
     new RegExp(`from\\s+['"]\\.\\.?/${escaped}['"]`),
   ];