- name
- understand-diff
- description
- Use when you need to analyze git diffs or pull requests to understand what changed, affected components, and risks
/understand-diff
Analyze the current code changes against the knowledge graph in the project's data directory (.ua/knowledge-graph.json, or the legacy .understand-anything/knowledge-graph.json when that directory is present).
Graph Structure Reference
The knowledge graph JSON has this structure:
project— {name, description, languages, frameworks, analyzedAt, gitCommitHash}nodes[]— each has {id, type, name, filePath?, summary, tags[], complexity, languageNotes?}- Code node types: file, function, class, module, concept
- Non-code node types: config, document, service, table, endpoint, pipeline, schema, resource
- Domain/knowledge node types: domain, flow, step, article, entity, topic, claim, source
- IDs use the node type as prefix, e.g.
file:path,function:path:name,config:path,article:path
edges[]— each has {source, target, type, direction, weight}- Key types: imports, contains, calls, depends_on, configures, documents, deploys, triggers, contains_flow, flow_step, related, cites
layers[]— each has {id, name, description, nodeIds[]}tour[]— each has {order, title, description, nodeIds[]}
How to Read Efficiently
- Use Grep to search within the JSON for relevant entries BEFORE reading the full file
- Only read sections you need — don't dump the entire graph into context
- Node names and summaries are the most useful fields for understanding
- Edges tell you how components connect — follow imports and calls for dependency chains
Instructions
-
Resolve the data directory
$UA_DIR. RunUA_DIR=$([ -d .understand-anything ] && echo .understand-anything || echo .ua)— this is the legacy.understand-anything/when it already exists, otherwise the new.ua/. Check that$UA_DIR/knowledge-graph.jsonexists. If not, tell the user to run/understandfirst. -
Get the changed files list (do NOT read the graph yet):
- If on a branch with uncommitted changes:
git diff --name-only - If on a feature branch:
git diff main...HEAD --name-only(or the base branch) - If the user specifies a PR number: get the diff from that PR
- If on a branch with uncommitted changes:
-
Read project metadata and check graph freshness — use Grep or Read with a line limit to extract the
"project"section, includinggitCommitHashasGRAPH_COMMIT_RAW, then:- Resolve it as a commit before using it in any Git diff. From the project root, compare the resolved commit with
git rev-parse HEADand inspect project-scoped committed and working-tree changes:GRAPH_COMMIT=$(git rev-parse --verify --end-of-options "${GRAPH_COMMIT_RAW}^{commit}" 2>/dev/null) git rev-parse HEAD git diff --name-only "$GRAPH_COMMIT" HEAD -- . git diff --cached --name-only -- . git diff --name-only -- . git ls-files --others --exclude-standard -- . - 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 before impact analysis that the graph may omit those changes. Suggest: Run
/understandto refresh the graph. - Run the commit diff only when
GRAPH_COMMIT_RAWresolves successfully. If the graph commit or Git metadata is missing, invalid, or unavailable, give a brief best-effort warning and continue instead of blocking.
- Resolve it as a commit before using it in any Git diff. From the project root, compare the resolved commit with
-
Find nodes for changed files — for each changed file path, use Grep to search the knowledge graph for:
- Nodes with matching
"filePath"values (e.g.,grep "changed/file/path")
- Nodes with matching