fix: add -L flag for screen log capture on macOS 4.00.03 (issue #96)#98
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fix: add -L flag for screen log capture on macOS 4.00.03 (issue #96)#98
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Adding .gitkeep for PR creation (default mode). This file will be removed when the task is complete. Issue: #96
Replace the version-dependent approach (native -Logfile for screen >= 4.5.1, tee fallback for older versions) with a unified screenrc-based approach that works on ALL screen versions including macOS bundled 4.00.03. The screenrc uses three directives: - `logfile <path>` sets the log file path (available since early screen) - `logfile flush 0` forces immediate buffer flush (no 10-second delay) - `deflog on` enables logging for all windows by default This eliminates the tee fallback which had reliability issues on macOS: - tee's write buffers may not be flushed before the session ends - TOCTOU race between session detection and file read was hard to mitigate Additional improvements: - Exit code capture via sidecar file ($? saved after command completes) - Enhanced retry logic with 3 retries and increasing delays (50/100/200ms) - Debug output responds to both START_DEBUG and START_VERBOSE env vars - Descriptive [screen-isolation] prefix on all debug messages Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…sue #96) New test cases in both JS and Rust: - Verify exit code capture from failed commands (nonexistent command → 127) - Verify stderr output is captured via screen logging - Verify multi-line output with correct exit code (JS only) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Update case study to document the complete fix history: - v0.24.9 partial fix (logfile flush 0 + tee retry) that failed on macOS - v0.25.0 complete fix (unified screenrc-based logging) that works on all versions - Root cause analysis of tee fallback reliability issues - Discovery of deflog on + logfile screenrc approach - Exit code capture bug documentation Add experiment scripts used in investigation: - test-screen-capture-issue96.js: Both native and tee path testing - test-screen-tee-forced.js: Force tee fallback path testing - test-screen-screenrc-logging.js: Screenrc-based logging validation - test-screen-dash-L-screenrc.sh: Shell-level screenrc + -L testing Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Bump JS package version from 0.24.9 to 0.25.0 (minor: new behavior) - Add changeset for the screen isolation fix - Add Rust changelog entry for PR #98 - Fix Rust formatting (cargo fmt) and clippy warning Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Move screen integration tests from isolation.test.js to screen-integration.test.js to keep isolation.test.js under the 1000-line limit (1070 → 804 lines). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
konard
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agent --version does not work in screen isolation…issue #96) Root cause: `deflog on` in screenrc only applies to windows created AFTER screenrc processing. In `screen -dmS` mode, the default window is created BEFORE screenrc is processed. The initial window never had logging enabled, causing all output to be silently lost on macOS screen 4.00.03. Fix: Add `-L` flag to screen invocation to explicitly enable logging for the initial window at creation time. Combined with `logfile <path>` in screenrc, `-L` logs to our custom path. The `-L` flag is available on ALL screen versions including macOS 4.00.03. Additional fixes: - Add --verbose flag support to args parser (sets START_VERBOSE=1) - Make DEBUG evaluation lazy so --verbose flag works at runtime - Fix prettier formatting issues flagged by CI - Revert manual version change in package.json (CI doesn't allow it) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…sue #96) Documents the discovery that `deflog on` only applies to NEW windows, not the initial window in `-dmS` mode. This was the root cause of the v0.25.0 failure on macOS screen 4.00.03. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
konard
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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This reverts commit 7ffa4db.
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Summary
Fixes #96 —
agent --versionproduces no output when run through$ --isolated screen -- agent --versionon macOS with screen 4.00.03.Root Cause
The previous fix (v0.24.9/PR #97) used
deflog onin screenrc to enable logging. However,deflog ononly applies to windows created AFTER screenrc is processed. Inscreen -dmSmode, the default window is created BEFORE screenrc processing — so the initial window (where the command runs) never had logging enabled. This caused all output to be silently lost.Fix
-Lflag to screen invocation:screen -dmS session -L -c screenrc ...-Lexplicitly enables logging for the initial window at creation time-Lis available on ALL screen versions (including macOS 4.00.03)logfile <path>in screenrc,-Llogs to our custom path--verboseflag support to args parser — setsSTART_VERBOSE=1so screen-isolation debug output is visible when troubleshootingisDebug()function instead of constant, so env vars set by--verboseflag are respected at runtimeecho $? > exitfile)logfile <path>,logfile flush 0,deflog onfor immediate flush and additional window coverageChanges
js/src/lib/screen-isolation.js-Lflag, lazyisDebug(), screenrc loggingrust/src/lib/isolation_screen.rs-Lflag, matching Rust implementationjs/src/lib/args-parser.js--verboseflag supportjs/test/screen-integration.test.jsjs/package.jsondocs/case-studies/issue-96/deflog ontiming issueKey Insight
From the GNU Screen manual:
deflog onsets "the default log state for all new windows." The word "new" is critical — the initial window in-dmSmode is not "new" from the screenrc's perspective. The-Lflag bridges this gap by enabling logging at window creation time.Test plan
-L+ screenrc approach works🤖 Generated with Claude Code