feat(callback): expose active lifecycle hook metadata

[kaligautier]

Link to Issue or Description of Change

• Closes: [Feature Request]: Expose current callback hook metadata in Context #6979

Problem:

Callbacks reused across lifecycle stages cannot determine which hook invoked them from the context they receive.

Solution:

Expose immutable CallbackInvocationInfo through Context.callback_info while a callback is running. The hook value is task-local, so nested or concurrent invocations cannot leak metadata into one another. Both canonical callbacks and plugin callbacks are covered, and the value resets to None outside callback execution.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Results:

• Callback, plugin, model, tool, agent, and live-flow suites: 247 passed
• Repository suite excluding the unrelated local Anthropic SDK incompatibility: 13,680 passed; the one sandbox-only loopback networking failure passes when rerun with local networking enabled
• pre-commit run --from-ref origin/main --to-ref HEAD: passed

Manual End-to-End (E2E) Tests:

Ran an InMemoryRunner with a MockModel and shared before/after model callbacks. The callbacks observed the expected scoped values and the context reset after execution:

[('before', 'before_model'), ('after', 'after_model')]

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

The remaining local Anthropic failures are also present without this change and come from the installed SDK version lacking OutputTokensDetails; this PR does not modify Anthropic code or dependency files.

[kaligautier]

Hi @DeanChensj, I’ve rebased the PR onto the latest main and resolved the conflict. It is mergeable again. Thanks!