fix(0.41.1): auto-update hook preserves [server] extras + kbagent version refreshes cache

[padak]

Summary

Two bugs combined to break kbagent serve --ui for users who installed with --with 'keboola-agent-cli[server]'. Symptoms observed in production today:

kbagent version                # shows "v0.41.0 available"
kbagent serve --ui             # auto-updates to v0.40.3 instead, then fails:
                               # ModuleNotFoundError: No module named 'fastapi'

Bug 1 — Startup auto-update hook drops [server] extras

The fix in v0.40.2 patched only the explicit kbagent update command (version_service._update_kbagent). The startup auto-update hook in auto_update._perform_update was left running the old bare uv tool install --upgrade git+... — no --with flag, so the FastAPI + uvicorn extras a user originally installed with --with 'keboola-agent-cli[server]' got silently dropped on every auto-update.

Fix: Refactored both paths to share build_kbagent_upgrade_command() in version_service.py. The helper probes importlib.util.find_spec('fastapi') (reliable proxy for "user originally installed with [server]") and pairs --with 'keboola-agent-cli[server]' with --force when extras are detected (--force is uv's documented way to combine --upgrade + --with since uv rejects them as a pair).

Bug 2 — kbagent version does not refresh the auto-update cache

get_versions() made a live GitHub round-trip but did NOT write the result back to ~/.config/keboola-agent-cli/version_cache.json. The 1-hour-TTL'd cache stayed pinned to whatever value the auto-update hook last wrote. The result: kbagent version correctly shows v0.41.0 available (live fetch), but a follow-up kbagent serve --ui on the same machine still auto-updates to whatever stale version the cache held (e.g. 0.40.3, written by an auto-update hook before 0.41.0 existed).

Combined with Bug 1, this produced the worst-case scenario: the version check says "new release available", serve --ui upgrades to a different older release, and fastapi disappears.

Fix: get_versions() now persists the freshly-fetched values via _write_cache (lazy-imported to avoid the auto_update ↔ version_service import cycle). Write failures are caught and logged at debug level so the version command never crashes on a read-only HOME / disk-full edge case.

Test plan

• TestPerformUpdate.test_update_preserves_server_extras — when fastapi is importable, _perform_update argv contains --force --with 'keboola-agent-cli[server]', NOT --upgrade.
• TestPerformUpdate.test_update_without_server_extras_uses_upgrade — when fastapi is NOT importable, argv contains plain --upgrade (no --with).
• TestVersionService.test_persists_freshly_fetched_versions_to_cache — get_versions() calls _write_cache with the latest kbagent + MCP values.
• TestVersionService.test_cache_write_failure_does_not_break_get_versions — cache write OSError does NOT propagate (best-effort).
• make check: lint + format + skill + version + changelog + error-codes all clean.
• Full test suite: 3313 passed, 7 skipped (0 failures).
• Manual verification: cd worktree && pip install -e .[server] && python -c "from keboola_agent_cli.auto_update import _perform_update; from unittest.mock import patch; ..." — confirmed argv inspection matches the expected commands in both branches.

Diff stats

 9 files changed, 231 insertions(+), 80 deletions(-)

• src/keboola_agent_cli/services/version_service.py: new module-level has_server_extras() + build_kbagent_upgrade_command(), removed the now-dead VersionService._has_server_extras static helper, refactored _update_kbagent to delegate.
• src/keboola_agent_cli/auto_update.py: _perform_update delegates to build_kbagent_upgrade_command().
• src/keboola_agent_cli/services/version_service.py: get_versions() persists cache.
• tests/test_auto_update.py: 2 new tests pinning extras / no-extras branches.
• tests/test_version_service.py: 2 new tests for cache write + failure handling.
• src/keboola_agent_cli/changelog.py: 0.41.1 entry.
• pyproject.toml, plugins/kbagent/.claude-plugin/plugin.json, .claude-plugin/marketplace.json: version bump.