Agent skill
fetch
Fetch the exact source code of a named symbol (function, class, method, type) from the codebase using the codemunch index. Reads only the lines for that symbol — not the whole file. Uses LSP for hover docs and type info when available. This is the core token-saving operation.
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/fetch
SKILL.md
Fetch Skill
Retrieve the exact source of a named symbol. Read 20 lines instead of 800.
Usage
Called with a symbol name, e.g.: validateToken, AuthService, getUserById, Invoice
Step 1 — Look up in index
# Read the index
cat .claude/codemunch/index.json | python3 -c "
import json, sys
idx = json.load(sys.stdin)
name = '$SYMBOL_NAME'
matches = [s for s in idx['symbols'] if s['name'].lower() == name.lower()]
print(json.dumps(matches, indent=2))
" 2>/dev/null
# Or with jq if available
jq --arg n "$SYMBOL_NAME" '[.symbols[] | select(.name | ascii_downcase == ($n | ascii_downcase))]' \
.claude/codemunch/index.json 2>/dev/null
If no index exists: the staleness-gate skill will have already built it before this skill runs.
If multiple matches (e.g. overloaded methods or same name in different files), show a disambiguation list and ask which one.
Step 2 — Extract the symbol source
Use the start_line and end_line from the index entry to read only those lines:
FILE="src/auth/tokens.ts"
START=142
END=163
# Add a few lines of context before (for decorators, comments, annotations)
CONTEXT_BEFORE=3
ACTUAL_START=$((START - CONTEXT_BEFORE))
[ $ACTUAL_START -lt 1 ] && ACTUAL_START=1
sed -n "${ACTUAL_START},${END}p" "$FILE"
Token count for this operation: ~20-40 tokens Token count for reading the full file: ~5,000-15,000 tokens
Step 3 — Enrich with LSP (when available)
If LSP is configured for this language, additionally fetch:
Hover information — type signature, documentation:
Use Claude Code's /lsp tool:
textDocument/hover
position: { line: START_LINE, character: 0 }
Type signature — already in index if built with LSP, but refresh if stale
Find references count — how many places call this symbol:
Use /lsp:
textDocument/references (just count, don't fetch all)
Step 4 — Display
Show the symbol in this format:
📍 validateToken [function] src/auth/tokens.ts:142-163
Engine: LSP | Signature: validateToken(token: string): Promise<User | null>
Container: AuthService | References: 14
─────────────────────────────────────────
[source code lines 139-163]
─────────────────────────────────────────
Tokens used: ~35 (vs ~8,400 to read full file — 99.6% savings)
Step 5 — Update usage stats
Append to .claude/codemunch/session.log:
fetch|validateToken|src/auth/tokens.ts:142-163|35 tokens|lsp
Fallback for missing end_line (rg-indexed symbols)
If end_line is null (rg fallback didn't have it), use a smart heuristic:
# Read from start_line until we find the closing brace at the same indent level
# or until the next function/class declaration
# Max 60 lines to avoid reading too much
awk -v start=$START_LINE -v max=60 '
NR==start { depth=0; capture=1 }
capture {
print
# Count opening and closing braces/blocks
for(i=1;i<=length($0);i++) {
c=substr($0,i,1)
if(c=="{" || c=="(" || c=="[") depth++
if(c=="}" || c==")" || c=="]") depth--
}
if(NR>start && depth<=0) exit
if(NR>start+max) exit
}
' "$FILE"
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