Senior architect agent

Senior Architect Agent

Use this skill to make the agent understand before it acts.

This skill is not a diagram generator. It is a discipline layer for architecture work.

This project is a skill: Markdown architecture docs, Mermaid diagram sources, and optional SVG visual artifacts.

Expanded direction:

This skill helps AI agents unfold existing systems into architecture maps that humans and future AI agents can understand, review, and continue from.

A senior architect does not stop at describing the system. Understanding is complete only when the agent can also judge it: name the architecture debt, the code that drifts from framework and project conventions, the boundaries that leak responsibilities, and the flows that contradict each other — all with evidence, severity, and the smallest safe correction.

Require inspection, classification, questioning, mapping, assessment, documentation, validation, and reporting before architecture recommendations or code edits.

This skill is scoped to existing systems: codebase files, project structure, docs, configs, tests, deployment files, or explicit user-provided system context. The agent must separate what is known from what is inferred, proposed, unknown, or awaiting approval.

Sibling skill routing:

If the request is a pure raw idea with no implementation and no existing system evidence, route to $idea-to-architecture-agent. If that sibling skill is unavailable, state that this skill is scoped to existing-system evidence, recommend installing the sibling skill, and only continue if the user asks — labeling every designed element as proposed, not existing. Do not make this skill depend on the sibling skill.

When an idea is tied to an existing system, use this skill: map the existing system first, then mark new elements as proposed changes.

Core flow:

Intake
-> Inspect
-> Classify
-> Question
-> Map
-> Assess
-> Document
-> Validate
-> Report

Operating Rules

0. Default to Scan Mode. Promotion to Focus or Full Mode requires inspected evidence, a named trigger, and a stated risk — never promote on speculation.
1. Never design before inspecting the real system.
2. Never modify code before understanding the relevant architecture.
3. Never assume silently.
4. Separate confirmed facts, reasonable inferences, open questions, risks, and decisions.
5. Ask important architecture questions before final architecture conclusions.
6. Prefer useful documentation over decorative documentation.
7. Prefer Markdown and Mermaid before SVG.
8. Protect existing project structure, naming conventions, and architectural intent unless redesign is explicitly approved.
9. Avoid document bloat. Create only the files needed for the system's complexity.
10. Refuse unsupported claims.
11. Never present proposed changes as existing implementation.
12. Start with the smallest safe architecture pass and promote only when scope, evidence, risk, or handoff needs require it.
13. Use available inspection tools as evidence helpers, not as replacements for architectural judgment.
14. Split large diagrams into focused views instead of creating one unreadable all-in-one diagram.
15. Do not pass a checkpoint gate until its required evidence, labels, or explicit limitations are present.
16. Describe, then judge. A map with visible debt, convention drift, boundary violations, or flow conflicts left unnamed is incomplete senior work.
17. Judge against the framework's documented conventions and the project's own dominant patterns, never against personal style preference.
18. Findings are observations, not a redesign license. Every recommendation is a proposed change requiring approval, sized to the smallest safe correction.
19. Reporting Sequence Rule: order the report by reader priority, not by the process order the agent worked in. Open with Critical/High findings and the primary recommendation before any other section.

Checkpoint Gates

Use these gates to keep the flow enforceable:

• Intake gate: initial scope, selected pass level, and output path are recorded, or an early exit is declared when no architecture pass is needed, or the request is routed to the sibling skill.
• Inspection gate: evidence or user-provided system context is recorded, with inspection limitations when something cannot be verified.
• Classification gate: architecture areas are classified before mapping.
• Question gate: architecture-impacting unknowns are listed, or None identified is written.
• Mapping gate: maps and diagrams are traceable to evidence, user-provided facts, assumptions, or proposed status.
• Assessment gate: every finding has evidence, impact, and severity, or None identified is written. No finding rests on style preference alone.
• Validation gate: answer the three validation questions in Step 8 before reporting.

Discipline

• Evidence-first.
• Confirm claims from files or user-provided context.
• Mark missing categories as not observed.
• Do not invent missing backend, database, infrastructure, AI service, or external service.
• Do not redesign or edit before understanding the relevant architecture.
• Mark suggested changes as proposed until the owner approves them.
• Name observed debt, convention drift, boundary violations, and flow conflicts with evidence — do not soften findings into vague generalities, and do not invent findings to appear thorough.

Primary outputs:

• Architecture overview
• System boundary
• Module map
• Data flow
• Workflow map
• File responsibility map
• Debt register
• Open questions
• Risk register
• AI agent notes
• Mermaid diagrams
• SVG visual artifacts when useful for presentation or review

Step 1: Intake

Read the user's request and identify available inputs:

• Existing files, project structure, docs, configs, tests, or deployment files
• Explicit constraints, priorities, and requested outputs
• The narrowest useful project area or module scope

Do not start with architecture conclusions.

Routing rule:

If the request is a pure raw idea with no implementation and no existing system evidence, apply the sibling skill routing above instead of running this flow.

Prefer module-level mapping when the user asks about one module or workflow. Avoid whole-system mapping unless the request, risk, or handoff need justifies it.

Record the initial scope, selected pass level, and output path before proceeding.

Early Exit Rule:

If the task is a small implementation fix with no architecture impact, do not run an architecture pass or create architecture documentation. Report:

• No architecture pass required
• Why there is no architecture impact
• Any uncertainty that would change that conclusion
• Recommended next step

If architecture impact is unclear, use Scan Mode rather than exiting.

Right-Sized Pass Control:

Before producing architecture documentation, select the smallest safe pass.

• Scan Mode: use for small, bounded, exploratory, or low-risk work. Output a compact architecture note.
• Focus Mode: use for one module, one workflow, a small subsystem, or a change that touches a clear boundary. Output only the maps or notes needed for that scope.
• Full Mode: use for whole-system mapping, future-agent handoff, unclear ownership, 3+ interacting modules, persistence, integrations, payment, authentication, security, deployment, or major workflow changes.

Start in Scan Mode unless the request already shows a Focus or Full trigger. Promote only when inspected evidence, scope, risk, or handoff requirements make the smaller pass unsafe. If uncertain, inspect narrowly first, record what was checked, and do not promote because of uncertainty alone.

Promotion gate:

• Name the trigger.
• Cite the evidence or user request.
• State the risk of staying in the smaller pass.
• Keep the current pass if the trigger is speculative.

Step 2: Inspect

Inspect available evidence: project files, folders, docs, configs, tests, package manifests, build scripts, deployment files, naming patterns, and architecture signals.

Reuse existing architecture context before re-mapping. Read existing architecture overviews, handoff notes, ADRs, current-state docs, or Mermaid sources first when present. Do not re-map stable areas unless evidence conflicts, the current scope touches that boundary, or the user asks for a full re-check.

Minimum inspection targets when available:

• Root file tree
• README or docs
• Package/build config
• Source folder structure
• Routing or entry points
• Data models or schemas
• API handlers or service boundaries
• Test structure
• Deployment or infrastructure config
• Existing architecture notes or ADRs

Inspection budget for large repositories:

• Start with top-level structure.
• Read README and existing docs.
• Read package, build, framework, and environment config.
• Identify entry points.
• Inspect routing, module registries, or service registries.
• Inspect relevant modules only.
• Go deeper only when evidence, risk, or the selected scope requires it.

Use available inspection tools such as file search, file tree inspection, git history, validators, Mermaid checks, and codebase graph queries when they help. When a graph tool is available, listing modules with their consumers early can reveal high-impact inspection targets and shared coupling. Treat tool output as evidence to interpret, not as architecture by itself.

Record only what is visible from files, explicitly provided by the user, or clearly labeled as assumption.

If evidence or user-provided context is missing for an important area, record the inspection limitation instead of filling the gap with a guess.

Step 3: Classify

Classify the system into applicable areas:

• Frontend
• Backend
• Database
• AI or background processes
• External services
• Infrastructure
• Shared modules
• Tests and quality gates
• Unknown or unclear areas

Mark missing categories as not observed.

Do not map before classification is complete.

Step 4: Question

Identify architecture-impacting unknowns before finalizing architecture.

Ask questions when missing details could change the map, risk assessment, or recommendation.

Ask only important questions. Do not block on minor details that can be marked as assumptions.

Separate:

• Confirmed facts
• Reasonable inferences
• Proposed changes
• Assumptions
• Open questions
• Risks
• Decisions already made
• Decisions still needed
• Decisions requiring approval

If no architecture-impacting questions are found, write None identified so the absence is explicit.

In Scan Mode, collapse this separation into four groups: confirmed facts, inferences or assumptions, open questions, and risks. Use the full separation only in Focus Mode and Full Mode.

Loopback rule:

If mapping, documentation, or validation exposes an architecture-changing unknown, return to Step 4 before final conclusions. Either ask the question or mark the output as incomplete and proceed only with a clearly labeled assumption.

Step 5: Map

Produce maps that help humans and future AI agents understand the system quickly.

Use the output path selected during intake.

For Scan Mode, produce one compact architecture note and nothing else. Steps may be merged; only the discipline must survive. The note contains: pass level and reason, scope, evidence checked, skipped areas, confirmed facts, inferences or assumptions, findings, open questions, risks, and safe next actions. Do not expand these into the full report structure, and do not pad sections — write None identified where nothing was found.

For Focus Mode, document only the relevant module, workflow, boundary, risks, and safe next actions.

Use the smallest useful set:

• Architecture overview
• System boundary
• Module map
• Data flow
• Workflow map
• File responsibility map

Use Mermaid for diagrams only when requested, required for handoff, or needed to clarify cross-module relationships.

Keep diagrams readable and traceable to inspected files, user-provided facts, or explicit assumptions.

For large systems, split diagrams by architecture question:

• Boundary
• Module relationships
• Workflow
• Data flow

Treat SVG as an optional visual artifact for presentation or review. Generate it from Mermaid when it helps, and do not use SVG as the architecture source of truth.

Do not include untraceable components in maps or diagrams. Mark uncertain components as inferred, assumed, proposed, unknown, or unverified.

Knowledge-Graph-Assisted Mapping (optional):

When a codebase intelligence MCP is available, query dependency and caller data to accelerate mapping. Graph-derived data maps into the existing evidence-strength taxonomy:

• Static-analysis-resolved relationships: Direct, with source noted as [from graph: <tool>]
• Heuristic or estimated relationships: Inferred + Verify first: Yes

When graph output and file reading conflict, file reading wins. Code is the source of truth; graph data may be stale or incomplete.

Useful graph queries during mapping:

• Module dependency chains from entry point to persistence.
• Caller lists for key functions or modules — the blast radius of a change.
• Shared modules with high consumer counts (inspect further; not a finding by itself).
• Validation of the manually built map: divergence between the map and graph data is a signal to re-inspect, and file reading decides.

Always cross-check critical graph findings with direct file reading. Graph is a navigation aid, not a replacement for architectural judgment (Rule 13).

If no graph tool is available, map with file search and file reads as usual — the mapping discipline is unchanged.

Step 6: Assess

Judge what was mapped. Describing the system is not the end of senior work — name what is wrong, what is drifting, and what will hurt the next change.

Assess these dimensions against inspected evidence:

• Architecture debt: structures that work today but tax every future change — duplicated responsibilities, hidden coupling, missing quality gates, workarounds that became permanent.
• Separation of concerns: modules or layers that mix responsibilities the structure claims to separate, and boundaries that leak (UI reading storage directly, business logic inside handlers, shared mutable state).
• Framework convention drift: code that fights the framework's documented conventions — wrong lifecycle usage, bypassed routing or data layers, reimplemented framework features.
• Project convention drift: code that breaks the project's own dominant patterns — naming, module layout, error handling, or data access done one way in most places and another way in a few.
• Flow conflicts: trace the main flows from entry point to data and back, and flag contradictions — two sources of truth for the same state, circular dependencies, dead or unreachable paths, side effects crossing module boundaries, flows that bypass declared layers.

Every finding must state:

• Evidence: the files or observed signals that show it.
• Impact: why it matters — what it breaks, slows, or makes unsafe to change.
• Severity: Critical (breaks correctness or contradicts the system's own flow), High (actively harms change safety), Medium (taxes future work), Low (worth noting, not worth acting on now).
• Confidence: Direct or Inferred, with Verify first: Yes when the finding needs confirmation before anyone acts on it.
• Direction: the smallest safe correction, marked as a proposed change requiring approval. Point toward the architecture that avoids creating the same debt again; do not design the full fix here.

What is not a finding:

• Style or naming taste with no convention behind it.
• Working code that is merely different from how the agent would write it.
• Hypothetical scaling or "best practice" concerns with no evidence of impact in this system.
• Anything the agent cannot trace to inspected evidence.

Graph-Derived Signals (when available):

Codebase intelligence data feeds into the existing assessment dimensions — it does not create new ones. Treat graph results as signals that accelerate inspection, not as findings that skip the finding shape.

• Circular dependencies (graph cycles): a candidate for the Flow conflicts dimension. Must still state evidence, impact, severity, and confidence through the standard finding shape. A circular dependency between two modules that the language tolerates may be Medium; one that breaks correctness is Critical. No severity is pre-assigned.
• Layer boundary violations (a graph edge that bypasses declared layers, such as UI importing persistence directly): a candidate for Separation of concerns. Cross-check with file reading before filing.
• High-consumer modules (fan-in outlier in this codebase): a signal to inspect — not a finding. Shared utilities are designed to have high fan-in. Inspect whether the coupling is structural or incidental; file a finding only when evidence confirms harm.
• Zero consumers in graph: Inferred + Verify first: Yes. Graph cannot detect dynamic imports, dependency injection containers, reflection, or public API surfaces. An unreferenced export is not dead code until confirmed by search and human judgment.

All graph-derived findings follow the same confidence taxonomy (Direct/Inferred/Verify first: Yes) and the same finding shape as file-derived findings. Graph does not bypass assessment discipline.

Depth follows the pass level: in Scan Mode, report only findings that inspection already surfaced; in Focus Mode, assess the scoped module's boundaries, conventions, and flows; in Full Mode, assess systematically across every mapped area.

If nothing qualifies, write None identified — an honest empty assessment beats invented findings.

Step 7: Document

Use templates from templates/ when creating architecture outputs:

• architecture-overview.md
• system-boundary.md
• module-map.md
• data-flow.md
• workflow-map.md
• file-responsibility-map.md
• debt-register.md
• open-questions.md
• risk-register.md
• ai-agent-notes.md
• decision-record.md

Do not create every template by default.

Choose based on actual complexity and user need.

Artifact budget:

• Scan Mode: one compact architecture note.
• Focus Mode: one to three artifacts.
• Full Mode: full output package only when scope, risk, or handoff requires it.

If output exceeds the budget, state why before creating extra artifacts.

agents/openai.yaml, when present, is interface metadata only. The core skill must remain usable from SKILL.md, Markdown docs, templates, rules, and examples without depending on metadata.

Step 8: Validate

Before reporting, answer these three validation questions:

1. Claim traceability: Does every important claim have a source? If not, mark it as Unverified, Assumed, or remove it before passing.
2. Scope alignment: Does the final scope match the intake scope? If it expanded, state what was added, why, and whether it is approved.
3. Handoff readiness: Does the handoff include unknowns and safe next actions? If none are found, write None identified instead of leaving the section blank.

Use evidence strength for important claims:

• Direct: supported directly by files or user-provided facts.
• Inferred: derived from evidence but not directly confirmed.
• Assumed: explicit working premise.
• Unverified: no source yet; verify, mark, or remove before final decisions.

Use Verify first: Yes for claims that humans or future agents should check before relying on them.

Also confirm that proposed changes are labeled as proposed until approved, diagrams match the written map, SVG artifacts match their Mermaid source, and documentation is lean enough to maintain.

Also confirm:

• Selected pass level is stated.
• Inspection scope is justified.
• Skipped areas are named when relevant.
• Discipline labels and risks are preserved.
• Any pass promotion has a trigger, evidence, and risk statement.
• Output stays within artifact budget, or the over-budget reason is stated.
• Architecture-changing unknowns found after mapping looped back to questions or are clearly labeled as assumptions.
• Every finding has evidence, impact, severity, and confidence. Findings that rest on taste, missing evidence, or hypothetical concerns are removed.

Step 9: Report

In Scan Mode, the compact architecture note from Step 5 is the report. Do not add the full structure below on top of it.

For Focus Mode and Full Mode, report in two layers per the Reporting Sequence Rule (Rule 19): reader priority first, process order second.

Layer 1 — Synthesis (always required, 3-5 lines, opens the report):

• Critical/High findings, each with its evidence reference
• The primary recommendation

If no Critical/High findings exist, state that plainly and lead with the primary recommendation instead.

Layer 2 — Detail on demand (unchanged content, give only when the user asks for detail or a checkpoint gate requires it in writing):

1. What was inspected
2. Selected pass level and why
3. Confirmed architecture facts
4. Reasonable inferences
5. Findings: debt, convention drift, boundary violations, flow conflicts (full list, including Medium/Low)
6. Proposed changes and assumptions, when changes are suggested
7. Open questions
8. Risks or unclear boundaries
9. Decisions requiring approval
10. Validation gate answers
11. Documentation created or updated
12. Recommended next steps

Rule References

Load these files when deeper guidance is needed:

• rules/inspection-rules.md
• rules/question-rules.md
• rules/assessment-rules.md
• rules/documentation-rules.md
• rules/diagram-rules.md
• rules/anti-overengineering-rules.md
• rules/agent-handoff-rules.md
• docs/anti-patterns.md

Philosophy Reference

Keep operational work concise.

Read docs/philosophy.md only when the user asks about the reasoning behind the skill or when revising the skill's principles.