feat: support interrupts from AfterToolCallEvent (#1165)

[alisknox]

Add interrupt support to AfterToolCallEvent.

Description

Extend AfterToolCallEvent with the _Interruptible mixin, allowing after-tool hook callbacks to pause agent execution.

On resume, the after-tool hook is replayed with the same event data (tool_use, result, exception, cancel_message) that was present at the time of interruption. The callback receives the interrupt result via event.interrupt() return value, and can then modify the result or request a retry.

Tools do not re-execute on resume unless the replayed hook explicitly sets retry=True.

Related Issues

#1165 (Solves primary use-case, other events interruptible is still nice to have)

Documentation PR

Type of Change

New feature

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

Within SSDP, executed the interrupt in the after tool call handler. Successfully re-hydrated and continued with the same context instead of needing the event.retry flag to resume from the before-tool hook.

• I ran hatch run prepare

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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[codecov]

Codecov Report

❌ Patch coverage is 90.74074% with 5 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/strands/event_loop/event_loop.py	80.00%	2 Missing and 3 partials ⚠️

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