fix(api): CORS credential leak + empty-scopes privilege escalation

[duyet]

Summary

Two security fixes, each in its own commit:

#345 — CORS reflects credentials for localhost origins in production, invalid wildcard-with-credentials

• ALLOWED_ORIGINS hardcoded localhost/127.0.0.1 entries that were also served in production (single Worker, no per-env origin list). Any page open on those loopback ports could make credentialed cross-origin calls to the production API.
• The handler answered Access-Control-Allow-Origin: * for a missing Origin, which is invalid alongside Access-Control-Allow-Credentials: true and rejected by browsers.
• For a disallowed origin it reflected ALLOWED_ORIGINS[0] (https://agentstate.app) instead of omitting the header — misleading, since the response advertised an allow-origin that didn't match the request.
• Fix: resolveAllowedOrigin() (packages/api/src/lib/cors.ts) returns null (no header) for a missing/disallowed origin, and only allows localhost origins when the Worker's ENVIRONMENT binding isn't "production". ENVIRONMENT=production is stamped only into the generated deploy config (prepare-wrangler-deploy-config.sh), so local wrangler dev and tests are unaffected.

#346 — Empty scopes array mints a full-access API key (privilege-escalation landmine)

• buildApiKey stored scopes: scopes && scopes.length > 0 ? JSON.stringify(scopes) : null. An explicit empty array ([]) collapsed to null, and effectiveKeyScopes(null) resolves to full access (*) — the opposite of "no permissions".
• services/keys.ts's response shaping had the identical bug.
• The delegation guards in routes/keys.ts and routes/v1-keys.ts used if (childScopes); changed to if (childScopes !== undefined) to make the undefined-vs-explicit-[] distinction explicit at the call site (functionally a no-op today since arrays are always truthy, but removes the ambiguity flagged by the audit).
• Only scopes === undefined (the field omitted entirely) now maps to null/full access. Legacy/unscoped keys (column null/absent) are unaffected and keep full access.
• Not currently reachable over HTTP (CreateApiKeySchema.scopes has .min(1), unchanged), but the lib/service layer is the security-relevant unit — any future caller (internal job, new route, MCP tool) that reaches createApiKey/buildApiKey with [] now gets a zero-permission key instead of a god key.

Closes #345
Closes #346

Test plan

• New regression tests in packages/api/test/cors.test.ts (unit tests for resolveAllowedOrigin covering missing/disallowed/production/dev-localhost cases, plus live SELF.fetch assertions that disallowed/missing origins get no Access-Control-Allow-Origin header) — all fail against the pre-fix code.
• New regression tests in packages/api/test/scopes.test.ts (buildApiKey/createApiKey with undefined vs. explicit [] scopes) — fail against the pre-fix code (previously resolved to null/full access).
• bunx biome check packages/api/src/ — clean
• bunx tsc --noEmit -p packages/api/tsconfig.json — clean
• cd packages/api && bunx vitest run — 366/366 passed (26 test files)

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 3765e20c-6f30-4cdf-a8f1-8691c8a6c84d

📥 Commits

Reviewing files that changed from the base of the PR and between aaf05ac and 9b9240b.

📒 Files selected for processing (10)

• packages/api/scripts/prepare-wrangler-deploy-config.sh
• packages/api/src/index.ts
• packages/api/src/lib/api-key.ts
• packages/api/src/lib/cors.ts
• packages/api/src/routes/keys.ts
• packages/api/src/routes/v1-keys.ts
• packages/api/src/services/keys.ts
• packages/api/src/types.ts
• packages/api/test/cors.test.ts
• packages/api/test/scopes.test.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/w7-api-security

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