Semantic code search. Use alongside grep - grep for exact strings, osgrep for concepts.
Finds code by meaning. When you'd ask a colleague "where do we handle auth?", use osgrep.
osgrep "where do we validate user permissions"
Returns ~10 results with code snippets (15+ lines each). Usually enough to understand what's happening.
ORCHESTRATION src/auth/handler.ts:45
Defines: handleAuth | Calls: validate, checkRole, respond | Score: .94
export async function handleAuth(req: Request) {
const token = req.headers.get("Authorization");
const claims = await validateToken(token);
if (!claims) return unauthorized();
const allowed = await checkRole(claims.role, req.path);
...
The snippet often has enough context. But if you need more:
# osgrep found src/auth/handler.ts:45-90 as ORCH
Read src/auth/handler.ts:45-120
Read the specific line range, not the whole file.
# Trace call graph (who calls X, what X calls)
osgrep trace handleAuth
# Skeleton of a huge file (to find which ranges to read)
osgrep skeleton src/giant-2000-line-file.ts
# Just file paths when you only need locations
osgrep "authentication" --compact
# 1. Find entry points
osgrep "where do requests enter the server"
# Review the ORCH results - code is shown
# 2. If you need deeper context on a specific function
Read src/server/handler.ts:45-120
# 3. Trace to understand call flow
osgrep trace handleRequest
If you see "Indexing" or "Syncing": STOP. Tell the user the index is building. Ask if they want to wait or proceed with partial results.