fix(gateway): add chat_id to session:start, session:end, and session:reset hook contexts

[AhmetArif0]

What does this PR do?

Root cause: _handle_message_with_agent() emits session:start and _handle_reset_command() emits session:end and session:reset, but none of them included chat_id in the hook context. Hook authors who subscribe to session lifecycle events cannot identify which conversation the session belongs to, making routing (e.g. sending a welcome message on session:start or cleanup on session:end) impossible without it.

Fix: mirror the "chat_id": source.chat_id or "" field added to agent:start by #24710 into the three sibling session hooks. source is in scope at all three emit sites and chat_id is a required str field on SessionSource, so no guard is needed beyond the existing or "" fallback.

Type of Change

• 🐛 Bug fix

Changes Made

• gateway/run.py: add "chat_id" to session:start (+1 line), session:end (+1 line), session:reset (+1 line) hook contexts
• tests/gateway/test_session_boundary_hooks.py: two new tests asserting chat_id is present in session:end and session:reset contexts

How to Test

pytest tests/gateway/test_session_boundary_hooks.py -v --override-ini="addopts="

Checklist

• Contributing Guide read | Conventional Commits | No duplicate PR
• Single logical change | Tests added | Platform: macOS
• Docs — N/A | Cross-platform — N/A

[teknium1]

Thanks for the focused lifecycle-hook fix. The omission is still present on current main: session:start lacks chat_id at gateway/run.py:10842-10847, and session:end / session:reset lack it at gateway/slash_commands.py:238-250.

Problems

• The PR's two reset edits target the pre-refactor location in gateway/run.py; _handle_reset_command moved to gateway/slash_commands.py in 619bd7827, so those hunks need to be applied there.
• tests/gateway/test_session_boundary_hooks.py adds coverage for session:end and session:reset, but not the new session:start field.
• The public event-context table at website/docs/user-guide/features/hooks.md:78-80 does not yet describe chat_id for these lifecycle events.

Suggested changes

• Move the reset payload additions to gateway/slash_commands.py:239-250 and add a session:start context assertion.
• Document the additive chat_id key for all three lifecycle events.

Automated hermes-sweeper review.

[teknium1]

Please add a companion regression test for this session:start payload. The new tests cover session:end and session:reset, but not this third added field.