TLDR zero-input false PASS — MC #900160

Incident

On 2026-08-23 the TLDR briefing/actionizer chain produced no actionable output. The absence of input is the incident signal; it must not be reported as a healthy run.

Verified current behavior

com.john.tldr-briefing finds zero eligible emails, writes a JSON sentinel with reason: no_unbriefed_emails, and exits 0.
com.john.tldr-actionizer reads zero insights, emits no result/task, and exits 0.
com.john.tldr-watch maps the zero-input sentinel to VERDICT=PASS.

This is fail-open observability: missing input is converted into green health and the operator receives no useful run result.

Required outcome

Explicitly distinguish a day when no TLDR run is expected from a scheduled run that expected input.
Any unexplained zero-input scheduled run returns actionable UNKNOWN or FAIL, never PASS.
The run output names the missing stage/source and preserves evidence.
Positive no-content policy, if retained for weekends/holidays, must be explicit and tested rather than inferred from a sentinel.

Implemented result

Live commit: 854aa1a5f.

The three stages now fail closed on zero input:

briefing writes error: true, reason: zero_input_error, emits ZERO_INPUT_ERROR, exit 2;
actionizer emits the source reason and exits 2 without fabricating a successful run;
watcher reports Verdict=FAIL, sends the actionable alert, and exits 2.

Positive control with five insights still completes with exit 0. Independent Gemini review returned PASS with zero unresolved P0/P1 findings.

Evidence

/Users/makinja/system/evidence/tldr-incident-2026-08-23/status.md
/Users/makinja/system/logs/tldr-briefing.log
/Users/makinja/system/logs/tldr-actionizer.log
/Users/makinja/system/logs/tldr-watch.log
/Users/makinja/system/logs/tldr-insights/2026-08-23.json
/Users/makinja/system/evidence/900160/runtime-controls.json
/Users/makinja/system/evidence/900160/live-chain-verification.txt
/Users/makinja/system/evidence/900160/gemini-review-clarification.json