[gspencergoog]

Summary

Implement renderer-to-agent outbound error mapping, RFC 6901 JSON Pointer error paths, and headless core conformance runner parity in @a2ui/web_core.

Reviewer Focus

• typescript/core/web_core/src/processing/message-error-mapper.ts:
  • extractEnvelopeErrorContext and mapErrorToRendererMessage map internal core errors to versioned ErrorMessage envelopes across v0.9, v0.9.1, and v1.0 protocols.
  • Correlation of functionCallId for envelope-level faults on callRendererFunction.
  • Normalization of RFC 6901 JSON Pointer paths (/components/0, /components/0/children/1).
• Dual-path error emission in MessageProcessor.ts and SurfaceGroupModel.ts:
  • Mapped ErrorMessage payloads are dispatched to surface.onError, model.onError, and outboundListener callbacks before errors are re-thrown in processMessages.
  • processMessagesWithErrors provides a non-throwing alternative for batch processing.
• Action context resolution in GenericBinder.ts:
  • Resolves individual entries in event.context without treating literal map keys path or call as binding directives.

Unit tests and CHANGELOG updates can be skimmed.

Changes

• Outbound error mapping:
  • Added src/processing/message-error-mapper.ts implementing MessageErrorMapper, extractEnvelopeErrorContext, and normalizeJsonPointer.
  • Re-exported error mapper utilities from src/processing/index.ts, src/v0_9/index.ts, and src/v1_0/index.ts.
• Error processing and event emission:
  • Added onError event hooks to SurfaceGroupModel and SurfaceComponentsModel.
  • Added processMessagesWithErrors to MessageProcessor.
  • Updated MessageProcessor.processMessages to emit mapped ErrorMessage instances to error listeners before rethrowing.
• Structured validation paths:
  • Updated payload-validator.ts and validation-helpers.ts to emit structured A2uiErrorDetail lists with canonical RFC 6901 JSON Pointer paths.
• Context binding and resolution:
  • Updated GenericBinder in src/resolution/generic-binder.ts to evaluate action context entries individually.
  • Aligned NodeResolver diagnostics with conformance expectations.
• Conformance test harness:
  • Updated tests/conformance/conformance_test.mjs and tests/conformance/node-resolution.ts to validate expectError.details, expectError.rendererError, strictMode, ValidationResult severity properties (isValid, validationErrors, validationResults), and surfaceId-scoped RPC dispatch.
• Documentation:
  • Updated CHANGELOG.md for @a2ui/web_core.

Impact & Risks

• Outbound ErrorMessage notifications are now emitted when processing invalid messages, giving agents structured feedback on protocol violations.
• Existing callers of MessageProcessor.processMessages continue to receive thrown errors; error listener callbacks are invoked prior to the throw.
• Action context bindings now cleanly separate literal dictionary keys from binding directives.

Testing

Run the build, conformance tests, and linter:

yarn --cwd typescript/core/web_core build
yarn --cwd typescript/core/web_core test:conformance
yarn --cwd typescript/core/web_core lint

_{🤖 Agent-generated}

[gemini-code-assist]

Code Review

This pull request introduces structured outbound renderer error mapping and reporting. It adds helper utilities mapErrorToRendererMessage and extractEnvelopeErrorContext to map internal A2uiError instances into spec-compliant ErrorMessage envelopes, and updates MessageProcessor to emit these errors via errorHandler, onError, and a new processMessagesWithErrors method. Additionally, it enhances validation errors with precise RFC 6901 JSON Pointer paths and updates conformance tests to validate these behaviors. The review feedback suggests replacing the in operator with Object.hasOwn in several files to avoid potential prototype lookup issues.

[ditman]

Thanks for taking a stab at this. I unleashed Carbon on this and it found a few things; most of them actually look legit, I'm surprised. LMK if things are not actionable enough, I can ask it to be more specific or prepare better suggestions!

[ditman]

Thanks for addressing the Round 1 feedback. Can you please fix the small leftover from earlier?

• Breaking OutboundMessageListener union widening (src/rpc/rpc-handler.ts): Now that MessageProcessor.handleProcessingError routes errors exclusively through errorHandler / onError and no longer calls outboundListener, OutboundMessageListener never receives ErrorMessage. Reverting rpc-handler.ts avoids an unannounced breaking compile-time change for @a2ui/web_core/v1_0 consumers narrowing OutboundMessageListener's message parameter.

The rest of my comments are nits, take as needed!