Include model_id and provider in AGENT_COMPLETE events

[Copilot]

Consumers of EventPublisher had to correlate AGENT_COMPLETE token usage against the SESSION_START manifest by agent name just to look up which model produced the usage — extra state to track for a simple cost calculation.

• Shared descriptor extraction: renamed manifest._model_descriptor to public manifest.model_descriptor(agent), no logic change, now reusable outside manifest building.
• Richer AGENT_COMPLETE payload: EventPublisher._on_complete now calls model_descriptor(event.agent) and adds model_id and provider to the event data, alongside the existing usage, text, and message.
• Docs: updated the event reference table to list the new fields.

# Before: had to join AGENT_COMPLETE.agent_name against the manifest to find model_id
# After:
async for event in ...:
    if event.type == EventType.AGENT_COMPLETE:
        cost = price_table[event.data["model_id"]].compute(event.data["usage"])

[galuszkm]

@copilot implement my comments

[galuszkm]

Would be better to have it collected as “model”:{“model_id”:…, “provider”: …}

[Copilot]

Done in b8f8e0b — payload is now "model": {"model_id": ..., "provider": ...}.

[galuszkm]

Lgtm

[Copilot]

Pull request overview

This PR improves the AGENT_COMPLETE event payload so consumers can attribute token usage to a specific model/provider without having to join against the SESSION_START manifest, which simplifies downstream cost calculation.

Changes:

• Exposes model descriptor extraction as manifest.model_descriptor(agent) (renamed from a private helper) for reuse outside manifest building.
• Enriches EventPublisher’s AGENT_COMPLETE payload with model identification data derived from the agent (model_id, provider).
• Adds a regression test and updates the docs event reference table to reflect the new payload fields.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
tests/runtime/test_event_stream.py	Adds coverage asserting AGENT_COMPLETE includes model identity info.
src/strands_compose/manifest.py	Makes model descriptor extraction a public helper used by multiple components.
src/strands_compose/hooks/event_publisher.py	Adds model identity information to AGENT_COMPLETE event data.
docs/configuration/Chapter_15.md	Documents the updated AGENT_COMPLETE payload fields.

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