feat: provide typed engagement message contracts

[kang-heewon]

Outcome

Adds @croco/engagement-core with Zod-backed message descriptors, fixed channel contracts, decorator-bound renderer registration, and runtime validation before rendering. It ships inspectable registry metadata and stable Problems for invalid definitions or bindings.

Fixes #1530

Verification

• package build, typecheck, tests (including a clean TypeScript 6 packed ESM/CJS consumer), and lint
• public API snapshot, Problem registry, package manifest, documentation catalog, and changeset checks

Review notes

• Correctness: renderer bindings preserve their instance receiver and reject a same-ID but different message definition.
• API/release: the new package has no transport or React dependency and includes generated API docs, Problem recovery entries, public-surface snapshot, and a minor changeset.
• Maintainability: registration is explicit and side-effect-free; the decorator only records metadata.

TypeScript does not contextually infer parameters of legacy class methods from implements. Strict examples therefore use MessageContext, which infers data and avoids repeating a per-channel generic.

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 5a4c113d-b483-474c-8ea8-92da46f3cc36

📥 Commits

Reviewing files that changed from the base of the PR and between 6795b4d and 38bf06b.

⛔ Files ignored due to path filters (2)

• packages/problems-core/src/generated/problem-code-registry.ts is excluded by !**/generated/**
• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (48)

• .changeset/typed-engagement-message-contracts.md
• .github/workflows/ci.yml
• README.md
• croco.arch.json
• docs/package-catalog.json
• docs/package-docs-report.md
• docs/problem-code-registry.json
• packages/docs/astro.config.mjs
• packages/docs/package.json
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageAlreadyRegisteredProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageDataInvalidProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageDefinitionInvalidProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererAlreadyRegisteredProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererBindingMismatchProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererChannelMissingProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererMessageMissingProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererMissingProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererRegistry.md
• packages/docs/src/content/docs/api/engagement-core/src/classes/MessageRendererUndeclaredChannelProblem.md
• packages/docs/src/content/docs/api/engagement-core/src/functions/Renders.md
• packages/docs/src/content/docs/api/engagement-core/src/functions/defineMessage.md
• packages/docs/src/content/docs/api/engagement-core/src/functions/getMessageRendererBinding.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/DefinedMessage.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageChannel.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageContent.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageContentByChannel.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageContext.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageData.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageDefinitionInput.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageDescriptor.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageRegistryInspection.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageRenderer.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageRendererBinding.md
• packages/docs/src/content/docs/api/engagement-core/src/type-aliases/MessageRendererConstructor.md
• packages/docs/src/content/docs/api/problems-core/src/classes/Problem.md
• packages/docs/src/content/docs/en/guides/getting-started.mdx
• packages/docs/src/content/docs/en/index.mdx
• packages/docs/src/content/docs/en/reference/problem-recovery-cookbook.md
• packages/docs/tsconfig.typedoc.json
• packages/engagement-core/README.md
• packages/engagement-core/package.json
• packages/engagement-core/src/index.ts
• packages/engagement-core/src/libs/MessageContracts.ts
• packages/engagement-core/src/tests/MessageContracts.spec.ts
• packages/engagement-core/src/tests/PublishedMessageContracts.spec.ts
• packages/engagement-core/src/type-tests/MessageContracts.types.ts
• packages/engagement-core/tsconfig.json
• public-api-surface.snapshot.json

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📊 Benchmark Results

✅ All benchmarks passed

Benchmark	p75	Threshold	Baseline	vs Baseline	Status	Notes
CrocoApp constructor	44.0μs	30.0ms	8.2μs	+438.3%	❌	-
CrocoApp lambdaHandler (10 controllers)	1.9ms	50.0ms	258.4μs	+616.2%	❌	-
Lambda cold-start simulation	1.9ms	80.0ms	418.1μs	+362.9%	❌	-
Lambda cold-start with headers	1.5ms	80.0ms	369.7μs	+316.9%	❌	-
Lambda cold-start with binary body	1.5ms	80.0ms	339.1μs	+353.2%	❌	-
Lambda cold-start with query params	1.5ms	80.0ms	301.3μs	+399.7%	❌	-
Lambda cold-start with authorizer context	1.5ms	80.0ms	299.8μs	+409.1%	❌	-
Lambda cold-start realistic scenario	1.5ms	80.0ms	299.2μs	+405.2%	❌	-
EventBusConfig.start (10 handlers)	1.7μs	10.0ms	1.4μs	+18.9%	✅	-
EventPublisher.publishNow single event	2.0μs	2.0ms	1.7μs	+17.9%	✅	-
DefaultHandlerResolver.resolve × 10	0.1μs	5.0ms	0.1μs	+1.3%	✅	-
Container.get singleton (cold)	87.6μs	5.0ms	70.3μs	+24.7%	❌	-
Container.register × 50 components	3.4ms	10.0ms	3.2ms	+6.7%	✅	-
Container.validate (50 components)	3.9ms	20.0ms	3.4ms	+14.4%	✅	-
Container.get singleton (warm)	1.6μs	500.0μs	1.6μs	-1.2%	✅	-
TelemetryRuntime.init (lambda preset)	2.2μs	200.0ms	1.1ms	-99.8%	✅	-
lambdaPreset config creation	1.5μs	2.0ms	1.4μs	+3.6%	✅	-

_{Updated: 2026-08-08T07:32:16.883Z · Commit: 448e004}

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Error details

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