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Use when identifying bottlenecks, waste, and failure modes in a service — designs PDSA improvement experiments with lane-anchored measures
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SOC 職業分類に基づく
Use when writing Rails controllers or implementing state changes - enforces resource extraction, thin controllers delegating to models, params.expect, and controller concerns for scoping
Use when designing database schema, writing migrations, or making data storage decisions - enforces UUIDs, account_id multi-tenancy, no foreign keys, and proper index patterns
Use when writing Hotwire (Turbo/Stimulus) code in Rails - enforces dom_id helpers, morph updates, focused Stimulus controllers, and JavaScript private methods
Use when writing background jobs or async operations - enforces thin job wrappers (3-5 lines) that delegate to models using _later/_now naming pattern
Use when writing Rails models - enforces state-as-records not booleans, concerns as adjectives namespaced under model, and concern extraction triggers
Use when naming classes, methods, routes in vanilla Rails codebases - enforces concern adjectives (-able/-ible only), no bangs for state, resource naming cascade, and commit message format
| name | service-diagnosis |
| description | Use when identifying bottlenecks, waste, and failure modes in a service — designs PDSA improvement experiments with lane-anchored measures |
Core principle: Diagnosis without measurement is opinion. Measurement without aim is vanity. Every improvement must state what gets better, for whom, and how you'd know.
This skill reads an existing blueprint. Run service-design:service-blueprint first. The blueprint's lanes, moments of truth, and failure modes are the raw material for diagnosis.
Mark fail points on the blueprint. For each, trace root cause across five categories:
| Category | What it catches |
|---|---|
| Policy | Rules that force bad outcomes — approval gates, eligibility traps, rigid scripts |
| Training | Staff lack knowledge or confidence to handle the scenario |
| System | Technical failures — downtime, latency, missing integrations |
| Handoff | Drops between teams, channels, or stages — no owner, no signal |
| Incentive | Metrics that reward behavior misaligned with customer outcomes |
Surface redundancies (duplicate work, conflicting ownership) and capacity constraints (queues, wait times, batching). These are structural — they won't appear in individual complaint data.
Map measures directly onto blueprint lanes. Measures that float free of lanes measure nothing actionable.
| Lane | Measures |
|---|---|
| Customer outcomes | Task success rate, time-to-value, perceived clarity |
| Frontline outcomes | Handle time, rework rate, escalation rate |
| System outcomes | Latency, defect rate, policy exception frequency |
State current and target for each. If current is unknown, tag [gap] — that gap is itself a finding.
For each top fail point, design a test: aim (what this proves), change (smallest safe experiment), measure (signal of success), expected outcome (prediction), risk/guardrail (stop condition), decision rule (scale if X, revert if Y). Small scale — one segment, one workflow, one week. Avoid big-bang rollouts.
When operational bottlenecks dominate — queues, rework, long lead times — diagram material and information flows end to end. Separate value-creating steps from waste (waiting, transport, overprocessing, duplication). The blueprint provides structure; the value stream map provides timing.
Optional but powerful. Score the service against five dimensions:
| Dimension | Question |
|---|---|
| Tangibles | Does the physical/digital evidence signal quality? |
| Reliability | Does the service deliver what it promised? |
| Responsiveness | Does the org act willing and fast? |
| Assurance | Do actors trust the service's competence? |
| Empathy | Does the service treat the person as individual? |
Map gaps to blueprint lanes. A reliability gap traced to a backstage handoff is actionable. A reliability gap floating in the abstract is not.
Tag every claim: [confirmed] (verified in code, data, or docs), [hypothesis] (inferred from patterns), or [gap] (unknown). For each hypothesis, note what would confirm or refute it.
Write to docs/service-design/<slice>/diagnosis.md using the template at service-design/templates/diagnosis.md. Populate the Aim Statement, Fail Points, Redundancies, Capacity Constraints, Lane-Anchored Measures, PDSA Tests, and SERVQUAL Assessment sections.
