Implementation Plan: Fix xdist Isolation — Hardcoded /dev/shm and /tmp Paths (groupB)

[Trecek]

Summary

Five audit findings (1.22, 1.24, 1.26, 1.27, 3.7) across three test files share a single root cause: hardcoded shared filesystem paths (/dev/shm/autoskillit-sessions, /tmp, /tmp/proj) used as test working directories or ephemeral roots. Under pytest-xdist -n 4, these shared paths become a race-condition surface. The fix redirects each path to a tmp_path-scoped location per the canonical xdist isolation patterns documented in tests/CLAUDE.md.

Architecture Impact

Concurrency Diagram

%%{init: {'flowchart': {'nodeSpacing': 40, 'rankSpacing': 50, 'curve': 'basis'}}}%%
flowchart TB
    classDef terminal fill:#1a237e,stroke:#7986cb,stroke-width:2px,color:#fff;
    classDef stateNode fill:#004d40,stroke:#4db6ac,stroke-width:2px,color:#fff;
    classDef handler fill:#e65100,stroke:#ffb74d,stroke-width:2px,color:#fff;
    classDef phase fill:#6a1b9a,stroke:#ba68c8,stroke-width:2px,color:#fff;
    classDef detector fill:#b71c1c,stroke:#ef5350,stroke-width:2px,color:#fff;
    classDef output fill:#00695c,stroke:#4db6ac,stroke-width:2px,color:#fff;
    classDef newComponent fill:#2e7d32,stroke:#81c784,stroke-width:2px,color:#fff;
    classDef gap fill:#ff6f00,stroke:#ffa726,stroke-width:2px,color:#000;

    START([task test-all])

    subgraph XDist ["PYTEST-XDIST ORCHESTRATOR"]
        RUNNER["pytest -n 4<br/>━━━━━━━━━━<br/>Spawns 4 worker<br/>processes"]
        QUEUE["WorkSteal Queue<br/>━━━━━━━━━━<br/>Distributes tests<br/>across workers"]
    end

    subgraph Workers ["PARALLEL WORKERS (×4 processes)"]
        direction LR
        W1["Worker 1<br/>━━━━━━━━━━<br/>tmp_path: unique<br/>per worker"]
        W2["Worker 2<br/>━━━━━━━━━━<br/>tmp_path: unique<br/>per worker"]
        W3["Worker 3<br/>━━━━━━━━━━<br/>tmp_path: unique<br/>per worker"]
        W4["Worker 4<br/>━━━━━━━━━━<br/>tmp_path: unique<br/>per worker"]
    end

    subgraph ModifiedTests ["● MODIFIED TESTS"]
        SS["● test_session_skills.py<br/>━━━━━━━━━━<br/>monkeypatch.setattr(<br/>ss._CANDIDATE_ROOTS, [tmp_path])"]
        HL["● test_headless.py<br/>━━━━━━━━━━<br/>cwd=str(tmp_path)<br/>instead of cwd='/tmp'"]
        AD["● test_headless_add_dirs.py<br/>━━━━━━━━━━<br/>proj=tmp_path/'proj'<br/>instead of '/tmp/proj'"]
    end

    subgraph Isolation ["ISOLATION AFTER FIX"]
        MP["monkeypatch scope<br/>━━━━━━━━━━<br/>Overrides _CANDIDATE_ROOTS<br/>Auto-restores on teardown"]
        TP["tmp_path / worker<br/>━━━━━━━━━━<br/>Unique dir per test<br/>No cross-worker writes"]
        CAND["_CANDIDATE_ROOTS → [tmp_path]<br/>━━━━━━━━━━<br/>resolve_ephemeral_root()<br/>returns tmp_path/autoskillit-sessions"]
    end

    SHARED["/dev/shm/autoskillit-sessions<br/>━━━━━━━━━━<br/>BEFORE FIX: global shared path<br/>Race: session name collisions<br/>cleanup_stale() interference"]

    PASS([PASS — no xdist races])

    START --> RUNNER
    RUNNER --> QUEUE
    QUEUE --> W1 & W2 & W3 & W4

    W1 & W2 & W3 & W4 -->|"each worker<br/>runs subset"| SS
    W1 & W2 & W3 & W4 --> HL
    W1 & W2 & W3 & W4 --> AD

    SS -.->|"before fix:<br/>race condition"| SHARED
    HL -.->|"before fix:<br/>race condition"| SHARED

    SS --> MP
    MP --> CAND
    CAND --> TP
    HL --> TP
    AD --> TP

    TP --> PASS

    class START,PASS terminal;
    class RUNNER phase;
    class QUEUE stateNode;
    class W1,W2,W3,W4 newComponent;
    class SS,HL,AD handler;
    class MP detector;
    class TP,CAND output;
    class SHARED gap;

Loading

Color Legend:

Color	Category	Description
Dark Blue	Terminal	task test-all entry and PASS result
Purple	Orchestrator	pytest-xdist runner
Dark Teal	State	WorkSteal queue, _CANDIDATE_ROOTS resolution
Green	Workers / Isolation	Per-worker processes; tmp_path isolation
Orange	Modified Tests	● Test files changed by this PR
Red	Synchronization	monkeypatch scope boundary
Amber	Gap (before fix)	Shared /dev/shm path — race surface

Implementation Plan

Plan file: /home/talon/projects/autoskillit-runs/impl-groupB-20260328-084620-500771/.autoskillit/temp/make-plan/fix_xdist_isolation_hardcoded_paths_plan_2026-03-28_085500.md

🤖 Generated with Claude Code via AutoSkillit

Token Usage Summary

Step	input	output	cached	count	time
group	2.7k	25.0k	721.4k	1	9m 3s
plan	462	84.7k	14.8M	9	41m 2s
verify	98	55.7k	3.3M	6	18m 12s
implement	536	45.2k	10.3M	9	25m 25s
fix	60	10.0k	1.6M	2	11m 53s
Total	3.8k	220.7k	30.7M		1h 45m

[Trecek]

[warning] cohesion: monkeypatch.setattr(ss, '_CANDIDATE_ROOTS', [tmp_path]) injects tmp_path directly as a candidate root rather than a subdirectory. Both tests in test_headless_add_dirs.py construct tmp_path / 'proj' via mkdir(). The convention for how tmp_path is used (raw vs. subdirectory) is inconsistent across the three files in this diff. Consider using tmp_path / 'root' with mkdir() for consistency.

[Trecek]

Investigated — this is intentional. resolve_ephemeral_root() at session_skills.py:54 appends 'autoskillit-sessions' to each candidate root, so tmp_path as a candidate root means all I/O lands in tmp_path/autoskillit-sessions/ — correctly isolated. test_resolve_ephemeral_root_fallback (line 37) also passes tmp_path directly without issue. The _CANDIDATE_ROOTS pattern (base dirs) and the cwd argument (project dirs) are different abstractions; surface consistency across them would be misleading.

[Trecek]

[info] cohesion: Creates proj = tmp_path / 'proj' with explicit mkdir(). Pattern is consistent within the file; note that test_headless.py passes str(tmp_path) directly as cwd without a subdirectory — minor inconsistency across the diff.

[Trecek]

[info] cohesion: Passes str(tmp_path) directly as cwd without creating a subdirectory (e.g. tmp_path / 'proj'), while tests in test_headless_add_dirs.py create an explicit proj subdirectory. The cwd construction pattern differs across the diff.

[Trecek]

AutoSkillit review found 1 blocking issue. See inline comments.

1 warning (changes_requested) and 2 info findings. The actionable finding is a cohesion inconsistency in how tmp_path is used across the three files — test_session_skills.py injects tmp_path directly as a _CANDIDATE_ROOTS entry while both add_dirs tests use tmp_path / 'proj' with mkdir().