Extract business domain knowledge from a codebase and generate an interactive domain flow graph. Works standalone (lightweight scan) or derives from an existing /understand knowledge graph.
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Extract business domain knowledge from a codebase and generate an interactive domain flow graph. Works standalone (lightweight scan) or derives from an existing /understand knowledge graph.
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Stars75,773
Forks6,313
LanguageTypeScript
LicenseMIT
📦 Ships with understand-anything
</> SKILL.md
understand-domain.SKILL.md
---name: understand-domain
description: Extract business domain knowledge from a codebase and generate an interactive domain flow graph. Works standalone (lightweight scan) or derives from an existing /understand knowledge graph.
argument-hint: "[--full]"
---# /understand-domain
Extracts business domain knowledge — domains, business flows, and process steps — from a codebase and produces an interactive horizontal flow graph in the dashboard.
## How It Works
- If a knowledge graph already exists (`.ua/knowledge-graph.json`, or the legacy `.understand-anything/knowledge-graph.json` when that directory is present), derives domain knowledge from it (cheap, no file scanning)
- If no knowledge graph exists, performs a lightweight scan: file tree + entry point detection + sampled files
- Use `--full` flag to force a fresh scan even if a knowledge graph exists
## Instructions
### Phase 0: Resolve `PROJECT_ROOT`
Set `PROJECT_ROOT` to the current working directory.
**Worktree redirect.** If `PROJECT_ROOT` is inside a git worktree (not the main checkout), redirect output to the main repository root. Worktrees managed by Claude Code are ephemeral — the data directory (`.ua/`, or legacy `.understand-anything/`) written there is destroyed when the session ends, taking the domain graph with it (issue #133). Detect a worktree by comparing `git rev-parse --git-dir` against `git rev-parse --git-common-dir`; in a normal checkout or submodule they resolve to the same path, in a worktree they differ and the parent of `--git-common-dir` is the main repo root.
if [ -n "$COMMON_DIR" ] && [ -n "$GIT_DIR" ]; then
COMMON_ABS=$(cd "$PROJECT_ROOT" && cd "$COMMON_DIR" 2>/dev/null && pwd -P)
GIT_ABS=$(cd "$PROJECT_ROOT" && cd "$GIT_DIR" 2>/dev/null && pwd -P)
if [ -n "$COMMON_ABS" ] && [ "$COMMON_ABS" != "$GIT_ABS" ]; then
MAIN_ROOT=$(dirname "$COMMON_ABS")
if [ -d "$MAIN_ROOT" ] && [ "${UNDERSTAND_NO_WORKTREE_REDIRECT:-0}" != "1" ]; then
echo "[understand-domain] Detected git worktree at $PROJECT_ROOT"
echo "[understand-domain] Redirecting output to main repo root: $MAIN_ROOT"
echo "[understand-domain] (Set UNDERSTAND_NO_WORKTREE_REDIRECT=1 to keep PROJECT_ROOT as the worktree.)"
PROJECT_ROOT="$MAIN_ROOT"
fi
fi
fi
```
Use `$PROJECT_ROOT` (not the bare CWD) for every reference to "the current project" / `<project-root>` in subsequent phases.
**Resolve the data directory `$UA_DIR`.** All Understand-Anything artifacts live in the project's data directory. Resolve it once, now that `$PROJECT_ROOT` is known, and reuse `$UA_DIR` for every read and write in later phases:
This keeps the legacy `.understand-anything/` directory when it already exists (existing projects keep working with no migration) and uses the new `.ua/` otherwise. Because each phase may run in a fresh shell, carry `$UA_DIR` forward like `$PROJECT_ROOT`, re-resolving it with the line above if a later command block needs it.
**Important:** do **not** assume the plugin root is simply two directories above the skill path string. In many installations `~/.agents/skills/understand-domain` is a symlink into the real plugin checkout. Prefer runtime-provided plugin roots first (for Claude), then fall back to universal symlinks, skill symlink resolution, and common clone-based install paths.
echo "Make sure the plugin is installed correctly."
exit 1
fi
```
Use `$PLUGIN_ROOT` for every reference to agent definitions in subsequent phases.
### Phase 1: Detect Existing Graph
1. Check if `$UA_DIR/knowledge-graph.json` exists
2. If it exists AND `--full` was NOT passed, check freshness before deriving from it:
- Read `project.gitCommitHash` from the graph metadata as `GRAPH_COMMIT_RAW`. Change to `$PROJECT_ROOT`, resolve it as a commit before using it in any Git diff, compare the resolved commit with `git rev-parse HEAD`, and inspect project-scoped committed and working-tree changes:
- The `-- .` pathspec is required: commits that only touch a sibling monorepo project must not make this graph stale. A hash mismatch alone is not stale when the project diff is empty.
- Ignore the selected data directory (`.ua/` or legacy `.understand-anything/`) in every command's output because it contains generated graph artifacts, not project source drift.
- If the committed diff or any working-tree command reports project files, warn that domain extraction may omit those changes. Suggest: Run `/understand` to refresh the knowledge graph.
- Run the commit diff only when `GRAPH_COMMIT_RAW` resolves successfully. If the graph commit or Git metadata is missing, invalid, or unavailable, give a brief best-effort warning and continue instead of blocking.
3. After that preflight, proceed to Phase 3 (derive from graph).
4. Otherwise, proceed to Phase 2 (lightweight scan). When `--full` is used, skip this preflight because the command performs a fresh scan instead of consuming the existing graph.
### Phase 2: Lightweight Scan (Path 1)
The preprocessing script does NOT produce a domain graph — it produces **raw material** (file tree, entry points, exports/imports) so the domain-analyzer agent can focus on the actual domain analysis instead of spending dozens of tool calls exploring the codebase. Think of it as a cheat sheet: cheap Python preprocessing → expensive LLM gets a clean, small input → better results for less cost.
1. Run the preprocessing script bundled with this skill, passing `$PROJECT_ROOT` from Phase 0:
