🐛 - Bugbot reports valid Python 3.14 PEP 758 exception syntax as a collection breaking SyntaxError #831

Is there an existing issue for this?

• I have searched the existing issues.

An exact search for PEP 758 found no existing issue. This is separate from progress output-contract failures #828, #829 and #830.

Which actions are affected?

Pull Request

Which platforms are affected?

Linux
macOS

Description

Bugbot publishes two medium-severity, 100%-confidence syntax-error findings for valid Python 3.14 exception handlers. One explicitly states that the project requires Python 3.14 but that except Conflict, StorageBusy: is a SyntaxError in that version. PEP 758 added this syntax in Python 3.14 when no as clause is present.

The declared consumer runtime is >=3.14,<3.15, Ruff target py314 and Python 3.14.6 in the executed backend suite. The exact flagged modules compile, collect and execute. The full backend CI passes 1387 tests with 100% supported statement/branch coverage. The reviewer should use the declared version and concrete parser/CI counterevidence before publishing a universal syntax-error claim or suggested change.

Expected: omit these findings for a Python 3.14 project; preserve a genuine compatibility finding when an actually supported older interpreter cannot parse the syntax. Keep required parentheses when an as clause is present. Do not suppress exception syntax findings globally or weaken review gates.

Actual: both findings incorrectly classify the new grammar as Python 2 syntax and claim pytest cannot collect, despite the successful exact-head suite.

Primary sources:

• https://peps.python.org/pep-0758/ (Final; Python-Version 3.14; unparenthesized multi-exception syntax without as).
• https://docs.python.org/3.14/whatsnew/3.14.html#pep-758-allow-except-and-except-expressions-without-brackets

Reproducing the issue

1. Consumer PR: Implement HA identity, SQLite persistence and verified restoration domus#7; exact analyzed head ead7dde44f57d32d5a42797a811e798d92b36a89.
2. Review run/job: https://github.com/vypdev/domus/actions/runs/41227372340/job/124614220480; native review 5724201125; check https://github.com/vypdev/domus/runs/124615649060.
3. Findings: Implement HA identity, SQLite persistence and verified restoration domus#7 (comment) at tests/backend/test_household_commands.py:415, and Implement HA identity, SQLite persistence and verified restoration domus#7 (comment) at tests/backend/test_member_commands.py:407.
4. Both statements are exactly except Conflict, StorageBusy: with no as clause. Both are valid under the project's required Python version.
5. Inspect pyproject.toml requires-python >=3.14,<3.15 and Ruff target py314, the Python pin and frozen CI setup. Run Python 3.14.6 compile(Path(file).read_text(), file, 'exec') on both exact modules: PASS.
6. Run the two test modules plus snapshot tests: 134 passed. The complete exact-head backend job passes 1387 tests: https://github.com/vypdev/domus/actions/runs/41227372378/job/124614220517. Both full CI Check aggregates pass on this exact head.
7. Minimal semantic reproduction on Python 3.14:

for kind in (ValueError, TypeError):
    try:
        raise kind('sentinel')
    except ValueError, TypeError:
        print(kind.__name__, 'caught')

Both exception types are caught. No parser compatibility fallback is involved.

copilot Version

vypdev/copilot@v3 resolved to 3e7ceea; codex codex-cli 0.166.0, reviewer model gpt-6-luna, smart effort.

Relevant Log Output

2026-10-31T18:07:22.3345747Z Bugbot reviewer completed partition 30/30.
analysisPartitions=30; completedAnalysisPartitions=30; analysisAssignedFiles=204
candidateFindings=3; publishedFindings=3

The two inline findings explicitly claim the modules raise SyntaxError during parsing. The third finding, a stale snapshot schema number in documentation, is valid and was corrected separately in normal commit 9c44195. No claim is made that all findings were false.

Additional context and comments

The analysis completed all 30 code partitions, but overall coverage is separately partial because human-conversation retained 6 of 9 items and omitted 3. We do not treat this as a complete review or merge acceptance. The PR remains unmerged. No Copilot implementation, installed resources, model/configuration, approval gate or language requirement was changed. Valid production/test syntax will not be rewritten just to hide a false positive; the response will cite actual runtime and primary-source evidence.

Suggested regression scope: valid >=3.14 syntax with/without as; a real <=3.13 compatibility target; except*; project runtime/version evidence; contrary successful parser/collection evidence. Live-model false-positive evidence and deterministic schema correctness should remain distinct. No credentials or owner HA identity/session data are included.