understand

What this skill does

# /understand

Analyze the current codebase and produce a `knowledge-graph.json` file in `.understand-anything/`. This file powers the interactive dashboard for exploring the project's architecture.

## Options

- `$ARGUMENTS` may contain:
  - `--full` — Force a full rebuild, ignoring any existing graph
  - A directory path — Scope analysis to a specific subdirectory

---

## Phase 0 — Pre-flight

Determine whether to run a full analysis or incremental update.

1. Set `PROJECT_ROOT` to the current working directory.
2. Get the current git commit hash:
   ```bash
   git rev-parse HEAD
   ```
3. Create the intermediate output directory:
   ```bash
   mkdir -p $PROJECT_ROOT/.understand-anything/intermediate
   ```
4. Check if `$PROJECT_ROOT/.understand-anything/knowledge-graph.json` exists. If it does, read it.
5. Check if `$PROJECT_ROOT/.understand-anything/meta.json` exists. If it does, read it to get `gitCommitHash`.
6. **Decision logic:**

   | Condition | Action |
   |---|---|
   | `--full` flag in `$ARGUMENTS` | Full analysis (all phases) |
   | No existing graph or meta | Full analysis (all phases) |
   | Existing graph + unchanged commit hash | Report "Graph is up to date" and STOP |
   | Existing graph + changed files | Incremental update (re-analyze changed files only) |

   For incremental updates, get the changed file list:
   ```bash
   git diff <lastCommitHash>..HEAD --name-only
   ```
   If this returns no files, report "Graph is up to date" and STOP.

7. **Collect project context for subagent injection:**
   - Read `README.md` (or `README.rst`, `readme.md`) from `$PROJECT_ROOT` if it exists. Store as `$README_CONTENT` (first 3000 characters).
   - Read the primary package manifest (`package.json`, `pyproject.toml`, `Cargo.toml`, `go.mod`, `pom.xml`) if it exists. Store as `$MANIFEST_CONTENT`.
   - Capture the top-level directory tree:
     ```bash
     find $PROJECT_ROOT -maxdepth 2 -type f -not -path '*/node_modules/*' -not -path '*/.git/*' -not -path '*/dist/*' | head -100
     ```
     Store as `$DIR_TREE`.
   - Detect the project entry point by checking for common patterns: `src/index.ts`, `src/main.ts`, `src/App.tsx`, `main.py`, `main.go`, `src/main.rs`, `index.js`. Store first match as `$ENTRY_POINT`.

---

## Phase 1 — SCAN (Full analysis only)

Dispatch a subagent using the prompt template at `./project-scanner-prompt.md`. Read the template file and pass the full content as the subagent's prompt, appending the following additional context:

> **Additional context from main session:**
>
> Project README (first 3000 chars):
> ```
> $README_CONTENT
> ```
>
> Package manifest:
> ```
> $MANIFEST_CONTENT
> ```
>
> Use this context to produce more accurate project name, description, and framework detection. The README and manifest are authoritative — prefer their information over heuristics.

Pass these parameters in the dispatch prompt:

> Scan this project directory to discover all source files, detect languages and frameworks.
> Project root: `$PROJECT_ROOT`
> Write output to: `$PROJECT_ROOT/.understand-anything/intermediate/scan-result.json`

After the subagent completes, read `$PROJECT_ROOT/.understand-anything/intermediate/scan-result.json` to get:
- Project name, description
- Languages, frameworks
- File list with line counts
- Complexity estimate

**Gate check:** If >200 files, inform the user and suggest scoping with a subdirectory argument. Proceed only if user confirms or add guidance that this may take a while.

---

## Phase 2 — ANALYZE

### Full analysis path

Batch the file list from Phase 1 into groups of **5-10 files each** (aim for balanced batch sizes).

For each batch, dispatch a subagent using the prompt template at `./file-analyzer-prompt.md`. Run up to **3 subagents concurrently** using parallel dispatch. Read the template once, then for each batch pass the full template content as the subagent's prompt, appending the following additional context:

> **Additional context from main session:**
>
> Project: `<projectName>` — `<projectDescription>`
> Frameworks detected: `<frameworks from Phase 1>`
> Languages: `<languages from Phase 1>`
>
> Framework-specific guidance:
> - If React/Next.js: files in `app/` or `pages/` are routes, `components/` are UI, `lib/` or `utils/` are utilities
> - If Express/Fastify: files in `routes/` are API endpoints, `middleware/` is middleware, `models/` or `db/` is data
> - If Python Django: `views.py` are controllers, `models.py` is data, `urls.py` is routing, `templates/` is UI
> - If Go: `cmd/` is entry points, `internal/` is private packages, `pkg/` is public packages
>
> Use this context to produce more accurate summaries and better classify file roles.

Fill in batch-specific parameters below and dispatch:

> Analyze these source files and produce GraphNode and GraphEdge objects.
> Project root: `$PROJECT_ROOT`
> Project: `<projectName>`
> Languages: `<languages>`
> Batch index: `<batchIndex>`
> Write output to: `$PROJECT_ROOT/.understand-anything/intermediate/batch-<batchIndex>.json`
>
> All project files (for import resolution):
> `<full file path list from scan>`
>
> Files to analyze in this batch:
> 1. `<path>` (<sizeLines> lines)
> 2. `<path>` (<sizeLines> lines)
> ...

After ALL batches complete, read each `batch-<N>.json` file and merge:
- Combine all `nodes` arrays. If duplicate node IDs exist, keep the later occurrence.
- Combine all `edges` arrays. Deduplicate by the composite key `source + target + type`.

### Incremental update path

Use the changed files list from Phase 0. Batch and dispatch file-analyzer subagents using the same process as above, but only for changed files.

After batches complete, merge with the existing graph:
1. Remove old nodes whose `filePath` matches any changed file
2. Remove old edges whose `source` or `target` references a removed node
3. Add new nodes and edges from the fresh analysis

---

## Phase 3 — ASSEMBLE

Merge all file-analyzer results into a single set of nodes and edges. Then perform basic integrity cleanup:

- Remove any edge whose `source` or `target` references a node ID that does not exist in the merged node set
- Remove duplicate node IDs (keep the last occurrence)
- Log any removed edges or nodes for the final summary

---

## Phase 4 — ARCHITECTURE

Dispatch a subagent using the prompt template at `./architecture-analyzer-prompt.md`. Read the template file and pass the full content as the subagent's prompt, appending the following additional context:

> **Additional context from main session:**
>
> Frameworks detected: `<frameworks from Phase 1>`
>
> Directory tree (top 2 levels):
> ```
> $DIR_TREE
> ```
>
> Framework-specific layer hints:
> - If React/Next.js: `app/` or `pages/` → UI Layer, `api/` → API Layer, `lib/` → Service Layer, `components/` → UI Layer
> - If Express: `routes/` → API Layer, `controllers/` → Service Layer, `models/` → Data Layer, `middleware/` → Middleware Layer
> - If Python Django: `views/` → API Layer, `models/` → Data Layer, `templates/` → UI Layer, `management/` → CLI Layer
> - If Go: `cmd/` → Entry Points, `internal/` → Service Layer, `pkg/` → Shared Library, `api/` → API Layer
>
> Use the directory tree and framework hints to inform layer assignments. Directory structure is strong evidence for layer boundaries.

Pass these parameters in the dispatch prompt:

> Analyze this codebase's structure to identify architectural layers.
> Project root: `$PROJECT_ROOT`
> Write output to: `$PROJECT_ROOT/.understand-anything/intermediate/layers.json`
> Project: `<projectName>` — `<projectDescription>`
>
> File nodes:
> ```json
> [list of {id, name, filePath, summary, tags} for all file-type nodes]
> ```
>
> Import edges:
> ```json
> [list of edges with type "imports"]
> ```

After the subagent completes, read `$PROJECT_ROOT/.understand-anything/intermediate/layers.json` to get the layer assignments.

`layers.json` may be either:
- a top-level JSON array of layer objects, or
- an envelope object such as