Merge pull request #1528 from colbymchenry/issue/671-mcp-supported-languages

feat(mcp): surface supported languages in MCP server instructions (recut of #678)

CHANGELOG.md

@@ -15,6 +15,8 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 - `codegraph_explore` no longer re-sends source it already returned earlier in the same conversation. A file it has already shown you comes back as a short pointer — the path, the symbols and the exact line range, with confirmation that the file hasn't changed since — and the space that frees is spent on code you haven't seen yet, so a follow-up call covers new ground instead of repeating the last one. If a file was edited in between, its source is always shown again in full. Set `CODEGRAPH_EXPLORE_DEDUP=0` to turn this off.
 
+- When an agent connects over MCP, CodeGraph now states up front that it indexes 30+ languages — TypeScript/JavaScript, Python, Go, Rust, Java, C#, C/C++, PHP, Ruby, Swift, Kotlin, and more — so agents no longer assume a language isn't supported and skip the graph. (#671)
+
 ### Fixes
 
 - A long-lived index no longer drifts away from what a fresh `codegraph index` would produce. When a file gained or lost a symbol, references to that name in files the sync never touched kept pointing at the definition that was correct before the change, and — because nothing distinguished two same-named definitions — the winner could come down to the order files happened to be written, which differs between a full index and a sync. On this project's own repository, replaying 80 commits through `sync` left 5.7% of connections wrong; it is now 1.3%, and the wrong-answers-still-being-asserted half drops by 99.7%. Since call edges are what flow questions follow and what `codegraph_explore` ranks files by, this quietly degraded answers as an index aged, with nothing to indicate it. Syncing is unchanged in speed, and an edit that only changes a function's body does no extra work at all. Set `CODEGRAPH_NO_REBIND=1` to opt out.

src/mcp/server-instructions.ts

@@ -22,8 +22,10 @@ export const SERVER_INSTRUCTIONS = `# Codegraph — code intelligence over an in
 Codegraph is a SQLite knowledge graph of every symbol, edge, and file in
 the workspace — pre-computed structure you would otherwise re-derive by
 reading files (cached intelligence: thousands of parse/trace decisions you
-don't pay to re-reason each run). Reads are sub-millisecond; the index lags
-writes by ~1s through the file watcher. Reach for it BEFORE *and* while
+don't pay to re-reason each run). It indexes 30+ languages
+(TypeScript/JavaScript, Python, Go, Rust, Java, C#, C/C++, PHP, Ruby, Swift,
+Kotlin, and more) — don't assume a language here isn't covered. Reads are
+sub-millisecond; the index lags writes by ~1s through the file watcher. Reach for it BEFORE *and* while
 writing or editing code — not just for questions: one call returns the
 verbatim source PLUS who calls it and what it affects, so you edit with the
 blast radius in view. More accurate context, in far fewer tokens and
@@ -87,7 +89,7 @@ calls; a grep/read exploration is dozens.
 export const SERVER_INSTRUCTIONS_NO_ROOT_INDEX = `# Codegraph — available (per-project; pass projectPath)
 
 Codegraph is a SQLite knowledge graph of a codebase's symbols, edges, and
-files: one \`codegraph_explore\` call returns the verbatim, line-numbered source
+files (30+ languages): one \`codegraph_explore\` call returns the verbatim, line-numbered source
 of the relevant symbols PLUS the call paths between them and a blast-radius
 summary — replacing a grep + Read loop with one round-trip.