# Architecture Assessment > Reconstruct a software system's current architecture from code, runtime wiring, tests, and history. Use for architecture discovery, a legacy-system assessment, or preparing a simplification effort; ordinary feature work does not require a whole-system assessment. - Skill: `aaronontheweb/architecture-assessment` (Agent Skill, multi-file: 9 files) - Install (CLI): `npx skillmds@latest add aaronontheweb/architecture-assessment` - Raw SKILL.md: https://api.skillmd.com/api/skills/aaronontheweb/architecture-assessment/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Product & Planning - Author: aaronontheweb (https://skillmd.com/u/aaronontheweb) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/aaronontheweb/architecture-assessment --- # Architecture assessment Explain how the system works, why its durable parts exist, and which constraints govern changes. This is an assessment; it does not authorize refactoring, deleting specifications, or changing policy. ## Establish the evidence boundary Identify the repository, revision, scope, and intended use of the result. Discover facts before asking the human for priorities or intent. Preserve existing checkout changes. When a clean baseline is needed, use a separate worktree from the agreed branch and record its commit. Do not substitute another fork or an unmerged branch without saying so. Initially read only the guidance and metadata needed to establish scope, languages, tooling, and the snapshot. Defer broad documentation and source exploration until the analyzer-first step below. Then read relevant existing documentation, treating historical plans as claims to check. Keep observed behavior, declared goals, inferred rationale, and desired changes distinct. This includes canonical glossaries: reuse supported distinctions, but label definitions that describe planned or retired behavior rather than importing them into the current architecture. Record missing evidence and contradictions instead of quietly reconciling them into invented truth. Distinguish the user's ranked goals from observed implementation choices. If a consequential decision depends on an unknown priority, ask about that trade-off rather than inferring a project constitution. ## Select only relevant implementation flavors The reasoning and outputs below apply across languages. Languages and execution surfaces supply additional evidence methods; they do not impose an architecture or create new personas. - For C#/.NET, read [the C# flavor](references/csharp.md). - For services, libraries, workers, or actor systems, read [backend evidence](references/backend.md). - For browser, native, terminal, or chat experiences, read [experience evidence](references/experience.md). Combine relevant flavors. When no flavor exists, use the repository's established tools and report their limits. Do not invent a plugin framework or another skill just to support a new tool. ## Always try the analyzer first Run the bundled [repository baseline](references/metrics.md) for the agreed commit first. When C# is in the assessment scope, attempt the [Roslyn collector](references/csharp.md), then build and query the [SQLite catalog](references/catalog.md) if collection succeeds. Do this before reading implementation bodies, tracing composition roots, delegating subsystem exploration, or drawing architectural conclusions. Direct source inspection and targeted greps are necessary later; they do not substitute for this step. Keep generated output outside tracked source, in an ignored local directory or external working area. Check revision, coverage, exclusions, and parse diagnostics. Query bounded file/type summaries to pick what to inspect next; do not dump the full inventory into context or treat size/name matches as findings. Report a short collection receipt: commit, commands and output paths, coverage/diagnostic limits, and the first query's inspection targets. A successful build alone is not a completed collection. An existing catalog can satisfy this step only after checking its revision, source hashes, collector identity, and configuration against this assessment. Otherwise regenerate it. In mixed-language scopes, the baseline covers all files but Roslyn covers only C#; use established tools and direct inspection for other languages without implying semantic coverage. Non-C# assessments do not require .NET or a C# catalog. If collection is blocked, report the failed command or missing prerequisite, cause, and smallest recovery step. Try safe, in-scope recovery; do not silently switch to manual inspection or keep retrying indefinitely. A disclosed failure permits a bounded manual assessment with explicit evidence gaps; it does not support claims that depend on the missing metrics. Ask for direction if those gaps prevent the requested outcome or recovery needs new authority. Only an explicit user instruction can waive the initial attempt; a small repository or confidence from grepping is not a reason to skip it. ## Reconstruct the system Use the inventory to bound products, processes, modules, dependencies, and existing verification. Trace representative journeys across boundaries, including an important failure or recovery path. For each substantial responsibility, establish: - its purpose, callers, consumers, and authoritative owner; - the state and resource lifetimes it owns; - contracts, side effects, dependencies, and ordering constraints; - how new behavior enters through existing seams; - tests or runtime evidence that support these claims. Inspect composition roots and indirect dispatch as well as static dependencies. Folder names and type counts alone do not establish bounded contexts or responsibility. Distinguish reusable mechanisms, platform adapters, and compatibility paths from competing implementations of the same responsibility. If parallel reviewers are authorized, divide by coherent subsystem or journey. Give each the same revision and evidence contract. Reconcile shared boundaries centrally; do not concatenate reports into an architecture. Treat source size as an investigation signal, not a reason to split a component. ## Produce a compact current model Use the existing canonical artifact when suitable. Otherwise create a small navigable report in the agreed workspace. Include a system overview, a diagram where relationships warrant it, responsibility and ownership boundaries, important contracts and journeys, evidence links, and known uncertainties. Keep detailed inventories in machine-readable output and historical rationale available by reference. Do not generate one document per class or reproduce the entire specification corpus. Use the [SQLite catalog](references/catalog.md) for selective queries and purpose annotations when available. Keep measured facts separate from inferred responsibilities; the catalog is a derived revision-scoped work product, not another canonical specification system. The report must identify the inspected revision, scope, measurement procedure, exclusions, and areas not inspected. Link conclusions to source locations and distinguish test inspection from test execution. Keep project-specific goals and lessons in the project; do not promote them into this shared skill. For multi-turn work, checkpoint coverage, evidence, open questions, and the next inspection step in the assessment artifact. Resume from that state. Completion means the agreed scope has a supported model and explicit gaps, not that every file has been read. Hand off to `simplify` only when requested; a missing runtime environment yields a partial claim, not fabricated verification. Reuse this model in a proposal rather than producing a competing architecture document. When asked to evaluate possible changes, consult [architectural-principles](../architectural-principles/SKILL.md) for relevant design defaults within the project's constraints. Describing the current system does not require a principles audit or report. After an authorized change, consolidate verified responsibilities and constraints into the current model; keep superseded decisions accessible through Git or the existing history instead of routine context.