fix(startup): propagate database setup failures

[NP-compete]

Summary

• _ensure_database() now re-raises exceptions instead of returning an error string, so run_startup() crashes before marking the pod ready
• Prevents pods from passing health checks while database tables are missing

Closes #216

Test plan

• test_db_failure_propagates -- verifies _ensure_database() re-raises ConnectionError
• test_not_ready_when_database_fails -- verifies run_startup() does not set _startup_complete = True when database setup fails
• All 15 startup tests pass

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📒 Files selected for processing (2)

• deep_agent/aegra/startup.py
• tests/unit/aegra/test_startup.py

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Walkthrough

_ensure_database() now re-raises database setup exceptions. run_startup() fails before setting the startup readiness flag. Tests cover startup propagation and PostgreSQL table setup failures.

Fixed issue severity: <fixed_issue_severity>Medium</fixed_issue_severity>

Suggested reviewers: anish701

Merge Risk: ⚪ Minimal · up to e4fac

The change keeps pods unready when database setup fails, preventing startup with missing tables; no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: propagating database setup failures during startup.
Description check	✅ Passed	The description accurately explains the startup failure behavior, readiness impact, linked issue, and test coverage.
Linked Issues check	✅ Passed	The changes satisfy issue #216 by propagating database failures and preventing startup readiness from being marked complete.
Out of Scope Changes check	✅ Passed	All code and test changes directly support database failure propagation and startup readiness behavior.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

🚀 Post-Merge Actions

• Update changelog

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[vishnusrichand]

LGTM