feat(server): idempotency: 'disabled' mode + standalone enum value arrays

[bokelley]

Summary

Two additive surfaces for the @adcp/client SDK aimed at consumers who currently UUID-inject every test payload to satisfy AdCP 3.0's idempotency_key requirement, or who duplicate spec enum literals in their own validation code.

1. idempotency: 'disabled' for createAdcpServer

AdcpServerConfig.idempotency now accepts 'disabled' | IdempotencyStore. When set to 'disabled':

• Capability declaration flips to the spec's IdempotencyUnsupported branch — get_adcp_capabilities returns adcp.idempotency: { supported: false } (no replay_ttl_seconds), matching the oneOf discriminator in the spec. Buyers reading caps fall back to natural-key dedup before retrying spend-committing operations.
• The replay middleware (INVALID_REQUEST / IDEMPOTENCY_CONFLICT / IDEMPOTENCY_EXPIRED) is skipped.
• Schema validation tolerates a missing idempotency_key on mutating tools — surgically, only the keyword: 'required', pointer: '/idempotency_key' issue is dropped; every other required field still produces VALIDATION_ERROR.
• A pre-middleware shape gate enforces IDEMPOTENCY_KEY_PATTERN whenever a key IS supplied, regardless of validation mode — defense-in-depth so malformed keys never reach handler logs.
• Throws at construction under NODE_ENV=production (silent double-execution on retry is a money-flow incident waiting to happen). Outside production, a logger.warn fires.

Production servers must still wire a real store via createIdempotencyStore({ backend, ttlSeconds }). The existing idempotency: store and idempotency: undefined paths are unchanged.

2. Standalone enum value arrays

New generated file src/lib/types/enums.generated.ts exports a ${TypeName}Values const array for every named string-literal union in the AdCP TypeScript types (122 enums: MediaChannelValues, PacingValues, MediaBuyStatusValues, DeliveryTypeValues, AssetContentTypeValues, …).

import { MediaChannelValues } from '@adcp/client/types';
const channels = new Set<string>(MediaChannelValues);
if (!channels.has(input)) throw new Error('unknown channel');

Codegen wired into npm run generate-types so ci:schema-check catches drift the same way it catches type drift. Inline anonymous unions (e.g., formats?: ('jpg' | ...)[]) are out of scope — they don't have stable names in the generated TypeScript.

Expert review caught a wire-level blocker

Initial implementation kept supported: true in get_adcp_capabilities even in disabled mode — three expert reviews (ad-tech-protocol-expert, code-reviewer, security-reviewer) converged on this as a money-flow footgun: a buyer reading caps and retrying after a 504 would double-book real spend. The spec's IdempotencyUnsupported branch (supported: false, no replay_ttl_seconds) is the correct shape and is now what disabled mode emits.

Other expert findings addressed: throw-on-production, pre-middleware shape gate, pinned the pointer-match invariant in a comment, bumped enum codegen floor from <20 to <100 to catch partial regex drift.

Test plan

• Unit tests in test/server-idempotency.test.js (+6): warn at construction, throw under NODE_ENV=production, schema filter is surgical (other required fields still fail), no replay, capability flips to supported: false, shape gate rejects malformed keys
• Wire-level e2e in test/server-idempotency-disabled-e2e.test.js (+5): real serve() + official @modelcontextprotocol/sdk Client over StreamableHTTPClientTransport; A2A roundtrip via createA2AAdapter; both validation: 'strict' and validation: 'off' paths
• Cross-validation tests in test/lib/enum-arrays.test.js (+6): every Values array round-trips against its matching Zod Schema; Pacing and MediaBuyStatus literals match the spec; ≥30 enum/schema pairs cross-checked
• npm run test:lib: 4941 pass, 0 fail, 6 skipped (pre-existing)
• Typecheck clean (tsc --noEmit --project tsconfig.lib.json)
• Reviewer: confirm storyboard runner auto-skip on supported: false is a follow-up (not a blocker) — compliance/.../universal/idempotency.yaml says supported: false sellers MUST skip, but the runner doesn't auto-detect today

Follow-ups (not in this PR)

• Storyboard runner auto-skip when agent declares idempotency.supported: false (file an issue)
• Inline anonymous enum extraction (image asset formats, video container formats etc. — different extractor needed since they don't have stable names)

🤖 Generated with Claude Code

[bokelley]

Addressed P0 + P2 hygiene; filed P1 as #932.

P0 — production gate inverted (76db06f). Allowlist NODE_ENV ∈ {'test', 'development'}; anything else (unset, 'production', 'staging', custom names) throws unless ADCP_IDEMPOTENCY_DISABLED_ACK=1. Strict ack-value matching — only literal '1' acknowledges, not 'true'/'yes' (prevents copy-paste typos).

New tests cover: NODE_ENV unset → throws (the actual Lambda case), 'staging' → throws, ack escape works, ack only accepts '1'.

P2.1 — generated-at timestamp dropped from enums.generated.ts (76db06f). New file, no in-band timestamp; git log + .generated.ts suffix are sufficient signal. Other generated files keep their existing timestamp convention (out-of-scope to refactor).

P2.2 — AgeVerificationMethod1Values: investigated. Both AgeVerificationMethod and AgeVerificationMethod1 are real types in core.generated.ts — json-schema-to-typescript emits the suffix when the same enum is referenced twice from different schema paths. Both are validly importable, and dedup-by-value would arbitrarily drop one and break the corresponding consumer import. Keeping as-is; the cosmetic fix is upstream in json-schema-to-typescript.

P2.3 — NODE_ENV mutation race: documented in a comment at the top of the production-gate test block. The before/after-with-finally pattern is safe under the current node:test serial-within-file default; if --test-concurrency ever raises that, we move to a child process.

P1 — inline anonymous unions filed as #932. The clean fix is Zod-introspection (named schemas expose .options / .def.options on union types) rather than regex-on-TS — different tool, different PR. Acceptance criteria + suggested naming convention in the issue.