Detects quality signals from tool outputs — test failures, type errors, and build failures — and records them for retrospectives and scoring

quality-event Hook

The quality-event hook fires after every tool call and inspects the output for quality signals. When it detects a test failure, type error, build failure, or rule violation, it records the event in the quality_events table. These events feed the quality scoring system and are surfaced in session retrospectives.

Trigger Event

Fires as a PostToolUse hook after every tool call completes. It primarily inspects outputs from:

Bash tool -- inspects stdout/stderr for test failure patterns, TypeScript errors, and build errors
MCP tools -- inspects text responses for rule violation patterns

What It Does

Reads the completed tool call output from JSON stdin
Scans for quality signal patterns using regex matching on the output text
Classifies the signal (test failure, type error, build failure, rule violation, or verification pass)
Writes a quality event to the quality_events table in the memory database
Exits silently -- no output to stdout

Detection Patterns

Signal Type	Patterns Detected	Score Impact
`test_failure`	`FAIL`, `✗`, `Tests failed`, `×` , vitest failure output	-3 per event
`type_error`	`error TS`, `Type error`, `tsc: error`	-2 per event
`build_failure`	`Build failed`, `esbuild: error`, `next build` error output	-4 per event
`rule_violation`	`CR-` violation patterns, canonical rule references	-3 per event
`vr_pass`	Verification commands returning expected output	+2 per event
`clean_commit`	Successful commit with no fixups	+5 per event

Data Storage

Quality events are stored in the quality_events table in the memory database (.massu/memory.db):

Column	Type	Description
`session_id`	TEXT	The current session identifier
`event_type`	TEXT	Signal type (e.g., `test_failure`, `vr_pass`)
`tool_name`	TEXT	The tool whose output triggered the signal
`details`	TEXT	Snippet of the matched output
`score_delta`	INTEGER	Positive or negative score adjustment
`created_at`	TEXT	UTC timestamp of the event

Integration with Quality Scoring

Quality events are aggregated by the massu_quality_score tool to produce a session quality score from 0 to 100:

Scores start at 50 per session
Each quality event applies its score_delta to the running total
The score is capped at 0 (minimum) and 100 (maximum)
Score weights are configurable in massu.config.yaml under quality.weights

Integration with Retrospectives

Quality events from the session can be surfaced as actionable items during review:

Test failures are listed with their tool context for targeted diagnosis
Type errors are grouped by file to show which modules need attention
Build failures are flagged as high-priority blockers
Rule violations are listed with the specific canonical rule violated

Performance

This hook must complete within 500ms. It achieves this with:

Regex-only pattern matching (no database reads, only one write)
Early exit if the tool output is empty or too short to contain meaningful signals
Single SQLite insert per detected signal

Tips

Use massu_quality_score to see the running score for your current session
Use massu_quality_report to view a trend over the last N sessions
Adjust score weights in massu.config.yaml to match your team's priorities -- for example, weight type errors more heavily if TypeScript safety is critical
The hook detects signals from vitest, TypeScript compiler, esbuild, and Next.js build output by default