feat(seer): Wire explorer chat write site through SeerRun outbox

[trevor-e]

Summary

• Adds optional run_type param to SeerAgentClient.start_run() — when provided and organizations:seer-run-mirror is on, routes through the outbox
• Explorer chat endpoint now passes run_type=SeerRunType.EXPLORER
• Other callers (trigger_autofix_agent, etc.) omit it, keeping the direct path unchanged

Stacked on #115111. Third write site conversion (after assisted-query and legacy autofix).

Test plan

• New test test_outbox_path_creates_run_and_returns_run_id verifies SeerRun creation, outbox dispatch, and run_id return via the client
• Existing test_post_new_conversation_calls_client updated to expect run_type=SeerRunType.EXPLORER
• mypy + ruff clean

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Missing OutboxFlushError handling in outbox path

High Severity

The outbox context with flush=True can raise OutboxFlushError if the signal receiver fails (e.g., Seer returns a 500, triggering a RuntimeError in handle_seer_run_create). This exception is not caught here, unlike the analogous code in search_agent_start.py which wraps the block in a try/except OutboxFlushError. Since OutboxFlushError does not inherit from SeerApiError, the endpoint's exception handler in organization_seer_agent_chat.py won't catch it either, resulting in an unhandled crash instead of a graceful error response.

 

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[cursor]

Outbox path skips explorer index triggering

Medium Severity

The outbox path returns early at line 380, completely bypassing _maybe_trigger_explorer_index_for_new_run. Since the explorer chat endpoint is the only caller passing run_type, all explorer runs routed through the outbox will never trigger project indexing or context-engine indexing, even when Seer's response indicates missing indexes. The response data containing has_explorer_index and has_org_project_context is consumed only in the receiver, which discards those fields.

Additional Locations (1)

• src/sentry/seer/agent/client.py#L387-L394

 

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