Web Terminal Empty Capture Blocker Fix Evidence

Task: fix blocker #4 from .omo/evidence/20260629-prepublish-heavy-review/final/blockers.md: command mode must not exit 0 or report evidence paths when tmux capture is empty or failed.

Scenario 1: RED regression proof

• Invocation: bun test script/web-terminal-visual-qa.test.ts before the production fix, with a new command-mode empty-capture test temporarily in that file.
• Binary observable: exit code 1; failure shows expected exit 1 but helper returned 0.
• Artifact: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/red-empty-capture-test.log
• Receipt: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/red-empty-capture-test.receipt.txt

Scenario 2: Focused automated regression tests

• Invocation: bun test script/web-terminal-visual-qa.test.ts script/web-terminal-visual-qa-command.test.ts
• Binary observable: exit code 0; 10 tests pass, including #given command mode captures an empty tmux pane #when rendering #then the helper rejects the evidence.
• Artifact: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/green-focused-tests.log
• Receipt: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/green-focused-tests.receipt.txt

Scenario 3: TypeScript script project check

• Invocation: bun run typecheck:script
• Binary observable: exit code 0; tsgo --noEmit -p script/tsconfig.json passed.
• Artifact: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/typecheck-script.log
• Receipt: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/typecheck-script.receipt.txt

Scenario 4: Live tmux-backed command success path

• Invocation: node script/qa/web-terminal-visual-qa.mjs --title "Live Command QA" --command "printf 'webterm-live-ok\\n'" --source-label "printf live marker" --evidence-dir .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/live-command-artifacts --dwell-ms 500 --no-browser
• Binary observable: exit code 0; terminal.txt and terminal-ansi.txt are each 86 bytes; terminal.txt contains webterm-live-ok and [web-terminal-visual-qa exit:0].
• Cleanup receipt: metadata records tmux kill-session; tmux ls check found no remaining omo_webterm session.
• Artifacts: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/live-command-artifacts/terminal.txt, terminal-ansi.txt, terminal.html, metadata.json
• Checks: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/live-command-checks.txt
• CLI stdout/stderr capture: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/live-command-cli.log

Scenario 5: Empty tmux capture CLI rejection

• Invocation: PATH=<fake-empty-tmux> node script/qa/web-terminal-visual-qa.mjs --title "Empty Command QA" --command "printf 'hidden\\n'" --source-label "fake empty tmux" --evidence-dir .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/empty-command-artifacts --dwell-ms 1 --no-browser
• Binary observable: helper invocation exits 1; stderr contains tmux capture was empty; no evidence files are written.
• Cleanup receipt: fake tmux temp dir removed with rm -rf; this scenario used no live tmux session.
• Artifact: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/empty-command-cli.log
• Checks: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/empty-command-checks.txt

Scenario 6: File-size and checker hygiene

• Invocation: pure LOC checks for changed files.
• Binary observable: script/qa/web-terminal-visual-qa.mjs 228, script/web-terminal-visual-qa.test.ts 224, script/web-terminal-visual-qa-command.test.ts 75; all under the 250 pure LOC ceiling.
• Artifact: .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/loc-check.txt
• Omitted: scripts/typescript/check-no-excuse-rules.ts was not present in this checkout; recorded in .omo/evidence/20260629-prepublish-blocker-fixes/web-terminal-empty-capture/no-excuse-checker-unavailable.txt and substituted bun run typecheck:script plus LOC checks.

Why this is enough

The RED test proves the pre-fix behavior accepted empty command-mode captures. The new regression test and direct fake-tmux CLI proof cover the blocker path with a non-zero, clear error and no bogus evidence files. The live tmux command proof covers the non-empty success path and confirms artifacts remain non-empty while cleanup completes.

Residual risk

PNG capture was intentionally omitted with --no-browser because the blocker is command-mode tmux transcript acceptance, not browser rendering. Existing file-replay/browser-render tests remain covered by the focused helper suite.