Let screen return casefile JSON without writing a case directory

[samrusani]

Summary

• coldscreen screen ... --no-write (and MCP no_write) skips the case directory for that run only: no mkdir, no memo, no casefile, no evidence.
• CLI --no-write prints the casefile JSON to stdout the same way --json does. The HTTP cache still stores 200s. --overwrite --no-write does not delete an existing directory. rerun did not grow the flag.
• Default persist path is unchanged. Findings, language control, and verdict enforcement still run in memory.

Test plan

• uv run pytest (744 passed)
• uv run ruff check . / ruff format --check .
• uv run mypy
• uv run python scripts/check_language.py
• CI checks 3.11 / 3.12 / 3.13, package, and audit

[greptile-apps]

Greptile Summary

The PR adds an explicit no-persistence mode while preserving the default audit-pack behavior and HTTP caching.

• Adds CLI --no-write support that emits casefile JSON without creating or modifying a case directory.
• Adds MCP no_write support with a null case_dir and an in-memory memo and verdict.
• Updates pipeline persistence gating, tests, architecture, operational guidance, and privacy documentation.

Confidence Score: 5/5

The PR appears safe to merge with no concrete blocking or non-blocking defects identified.

The no-write flag is propagated consistently through CLI and MCP entry points, skips every case-directory mutation, preserves HTTP caching, and leaves the existing persistence path unchanged.

Important Files Changed

Filename	Overview
src/coldscreen/pipeline.py	Adds a keyword-only no-write mode that bypasses overwrite checks and case persistence while retaining the complete in-memory screening pipeline.
src/coldscreen/cli.py	Exposes --no-write, emits casefile JSON once, and reports persistence and failure status through stderr appropriately.
src/coldscreen/mcp_server.py	Adds the no_write tool argument and returns successful no-write results with a null case_dir.
tests/test_cli.py	Covers JSON output, absent and existing case directories, overwrite interaction, help text, and continued HTTP caching.
tests/test_mcp_server.py	Covers the expanded MCP schema and successful no-write payload without case-directory creation.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[CLI or MCP screen request] --> B[Run screening pipeline]
    B --> C[Build casefile and memo in memory]
    C --> D{no_write?}
    D -- Yes --> E[Skip case-directory persistence]
    E --> F[Return casefile, memo, verdict, and null case_dir]
    D -- No --> G[Write memo, casefile, and evidence]
    G --> H[Return persisted case directory]
    B --> I[HTTP cache reads and successful writes]
    I --> C

Loading

_{Reviews (1): Last reviewed commit: "Let screen return casefile JSON without ..." | Re-trigger Greptile}