agent-lab/docs/plans/todo-45.5-composed-schema-and-copy-failures.md

Todo 45.5 Composed Schema and Copy Failures Plan

Status: done

Result

Added immutable validation summaries and conservative branch-aware fallback classification. Uncopyable/non-JSON resolver and provider arguments produce stable results without exception leakage or definition-error misclassification.

Goal

Restore the cost-sensitive fallback contract for composed schemas and ensure argument isolation cannot leak copy exceptions or misclassify input failures as plugin-definition failures.

Scope

• Classify anyOf/oneOf branches so a missing field in an unrelated branch cannot make complete-invalid input eligible for fallback.
• Preserve fallback for a viable branch that fails only because required data is missing.
• Replace exposed/deep-copied ValidationError values with registry-owned immutable validation summaries needed by the kernel.
• Normalize strict JSON snapshot failures for deterministic resolver and provider-resolved arguments in both async and sync paths.

Boundaries

• Prefer a conservative fallback decision: no LLM call when branch viability is ambiguous or any candidate failure is substantive rather than missing-only.
• Do not implement a general JSON Schema inference engine or discriminator extension.
• Non-JSON and uncopyable values are invalid event arguments/resolution data; do not coerce them.
• Preserve the four already verified Todo 45.4 behaviors.

Files

• Modify: src/agent_lab/application/events/kernel.py
• Modify: src/agent_lab/application/events/registry.py
• Modify: tests/test_event_kernel.py
• Modify: tests/test_event_agent.py only if EventAgent integration needs a regression

Requirement Execution Loop

Plan

1. Add RED tests for discriminated anyOf and oneOf: target branch complete-but-wrong-type, unrelated branch missing fields, fallback count zero.
2. Add RED tests proving a matching/viable branch with only required fields missing can still call fallback once.
3. Add RED tests for argument objects whose __deepcopy__ raises in resolver and provider-resolved inputs; assert no exception escapes and no DEFINITION_ERROR misclassification.
4. Introduce immutable validation issue summaries and branch-aware missing-only classification.
5. Use strict JSON snapshots at argument isolation boundaries and normalize failures consistently across sync/async execution.

Act

• Cover both anyOf and oneOf with discriminator-like const branches.
• Verify complete-invalid input returns INVALID_ARGUMENTS, used_fallback=False, fallback calls 0.
• Verify a matching branch missing only its required value invokes fallback exactly once; fully ambiguous invalid input remains no-fallback.
• Prove validation summaries cannot mutate registry behavior and do not retain caller-owned instances or schema objects.
• Preserve handler/result mutation isolation for ordinary nested JSON values.

Observe

Confirm the LLM fallback count now reflects genuinely missing information, and malformed argument objects are contained as stable user/resolution failures rather than exceptions or definition errors.

Update

• Re-run Todo 45 specification and quality reviews over the full range.
• Mark Todos 45 through 45.5 done only after fresh verification.

Verification

• UV_CACHE_DIR=.uv-cache uv run pytest tests/test_event_kernel.py tests/test_event_agent.py -q
• UV_CACHE_DIR=.uv-cache uv run pytest
• git diff --check