chore(release): 0.12.9

[mikehasa]

Release

Version bump only — pyproject.toml + CHANGELOG.md. This release carries the gpt-6.1-sol pricing fix (#351), merged just before it.

• pyproject.toml → version = "0.12.9"
• CHANGELOG.md → ## [0.12.9] — 2026-09-30 with the fix entry, [Unreleased] re-pointed at v0.12.9...HEAD

apps/agentacct/Scripts/build-app.sh derives CFBundleShortVersionString and CFBundleVersion from pyproject.toml; there is no third version string.

DMG preflight (§3a) — decision: REBUILD (§3c)

The DMG is not just the Swift app: it embeds the frozen Python CLI (build-app.sh copies packaging/dist/agentacct/ into agentacct.app/Contents/Resources/cli). A Python-only change still changes what the DMG runs.

$ git diff v0.12.8...HEAD --stat -- src/agentacct apps/agentacct packaging
 src/agentacct/cost.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

$ git diff v0.12.8...HEAD -- pyproject.toml | grep -iE '^\+|^-' | grep -i depend
(no dependency change)

src/agentacct/** changed, so the payload changed → REBUILD. Reusing the 0.12.8 DMG would ship users the old price table and silently drop the fix. The 0.12.9 DMG will be built, signed, notarized and stapled from this release's own squash commit (never from the pre-squash release branch), then verified with packaging/verify-dmg.sh before it is attached to v0.12.9.

Test plan

• pytest -q tests/test_publish_workflow.py tests/test_rename_compat.py tests/test_pricing_catalog.py → 57 passed
• Wheel builds as agentacct-0.12.9-py3-none-any.whl (pip wheel --no-deps .)
• CI: pytest 3.11 / 3.12 / 3.13 + macOS app and UI snapshots (tag/version agreement is enforced by the build job)
• No paid provider/API calls were run — the only data fetched during this work was LiteLLM's public model_prices_and_context_window.json

Safety checklist

• Preserves local-first behavior (the new builtin rows need no network)
• Does not store API keys or secrets
• Does not expose localhost services publicly by default
• Does not control processes agentacct did not start
• Provider/API forwarding remains opt-in and budget-gated
• JSON output paths remain machine-readable

Docs

• CHANGELOG.md updated; the fix's user-facing behavior is described there
• No public docs claim more than the change does: coverage is per model, prices are list-price estimates, and stored rows need the documented repair command