fix: stop silent fuzzy symbol substitution (#1473) (#1809)

Adapt @uvmplus's PR #1481 (3ecf7479) to the shared symbol lookup and
named-symbol flow resolver on current main. Missing names return not found
with suggestions, and exact matches with no callers stay empty.

Preserve #1512 definition grouping and --file narrowing, #173 qualified
misses, and codegraph_node's intentional fuzzy file lookup. Port the
upstream regression suite and cover the moved shared lookup paths.

Validation on Linux with Node 22: project build, 74 requested tests,
47 related flow tests, and 16 same-fixture CLI/MCP checks pass. Baseline
captured 12 failing tests and 13 failing fixture checks.

Fixes #1473.
Supersedes #1481.

Co-authored-by: Colby McHenry <colbymchenry@users.noreply.github.com>

CHANGELOG.md

@@ -136,6 +136,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ### Fixes
 
 - `codegraph callers`, `codegraph callees` and `codegraph impact` now resolve qualified names, group results and JSON edges by definition, and accept `--file` to narrow ambiguous names; thanks @ferrine. (#1512, #1656)
+- `codegraph callers`, `codegraph callees` and `codegraph impact` (CLI and MCP) now report missing names with did-you-mean suggestions instead of another symbol's results, and exact matches with no callers stay empty; thanks @uvmplus. (#1473, #1481)
 
 #### MCP / indexing
 

__tests__/no-silent-fuzzy-symbol.test.ts

@@ -0,0 +1,217 @@
+/**
+ * #1473 — callers/callees/impact must not silently answer for a different
+ * symbol when the requested name has no exact match (or has an exact match
+ * with zero callers). Fuzzy FTS hits may appear only as did-you-mean hints.
+ */
+
+import { describe, it, expect, beforeAll, beforeEach, afterEach } from 'vitest';
+import { execFileSync } from 'child_process';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import { initGrammars, loadAllGrammars } from '../src/extraction/grammars';
+
+const BIN = path.resolve(__dirname, '../dist/bin/codegraph.js');
+
+beforeAll(async () => {
+  await initGrammars();
+  await loadAllGrammars();
+});
+
+function hasSqliteBindings(): boolean {
+  try {
+    const { DatabaseSync } = require('node:sqlite');
+    const db = new DatabaseSync(':memory:');
+    db.close();
+    return true;
+  } catch {
+    return false;
+  }
+}
+const HAS_SQLITE = hasSqliteBindings();
+
+function tmpRoot(prefix: string): string {
+  return fs.mkdtempSync(path.join(os.tmpdir(), prefix));
+}
+
+function rmTree(dir: string): void {
+  if (fs.existsSync(dir)) fs.rmSync(dir, { recursive: true, force: true });
+}
+
+function runCli(args: string[], cwd: string): { stdout: string; status: number } {
+  try {
+    const stdout = execFileSync(process.execPath, [BIN, ...args], {
+      cwd,
+      encoding: 'utf-8',
+      env: {
+        ...process.env,
+        CODEGRAPH_NO_DAEMON: '1',
+        CODEGRAPH_TELEMETRY: '0',
+      },
+      stdio: ['ignore', 'pipe', 'pipe'],
+    });
+    return { stdout, status: 0 };
+  } catch (err: unknown) {
+    const e = err as { stdout?: string; status?: number };
+    return { stdout: e.stdout ?? '', status: typeof e.status === 'number' ? e.status : 1 };
+  }
+}
+
+describe.skipIf(!HAS_SQLITE)('no silent fuzzy substitution (#1473) — MCP', () => {
+  let projectRoot: string;
+  let cg: any;
+  let handler: any;
+
+  beforeEach(async () => {
+    projectRoot = tmpRoot('codegraph-1473-mcp-');
+    const src = path.join(projectRoot, 'src', 'a', 'b', 'c');
+    fs.mkdirSync(src, { recursive: true });
+    fs.writeFileSync(
+      path.join(src, 'D.java'),
+      `package a.b.c;\n\npublic class D {\n    public void e()  { System.out.println("e"); }\n    public void ef() { System.out.println("ef"); }\n}\n`
+    );
+    fs.writeFileSync(
+      path.join(src, 'Caller.java'),
+      `package a.b.c;\n\npublic class Caller {\n    public void callsEfOnly() { D d = new D(); d.ef(); }\n    public void alsoCallsEf() { D d = new D(); d.ef(); }\n}\n`
+    );
+    // Case-differing pair: exact Fetch has 0 callers; lowercase fetch has callers.
+    fs.writeFileSync(
+      path.join(projectRoot, 'src', 'Fetch.cs'),
+      `public class Torture {\n  public void Fetch() {}\n}\n`
+    );
+    fs.writeFileSync(
+      path.join(projectRoot, 'src', 'fetch.py'),
+      `def fetch():\n    return 1\n\ndef load():\n    return fetch()\n`
+    );
+
+    const CodeGraph = (await import('../src/index')).default;
+    const { ToolHandler } = await import('../src/mcp/tools');
+    cg = CodeGraph.initSync(projectRoot);
+    await cg.indexAll();
+    handler = new ToolHandler(cg);
+  });
+
+  afterEach(() => {
+    handler?.closeAll();
+    cg?.destroy();
+    rmTree(projectRoot);
+  });
+
+  async function text(tool: string, args: Record<string, unknown>): Promise<string> {
+    const res = await handler.execute(tool, args);
+    return res.content?.[0]?.text ?? '';
+  }
+
+  it('callers: missing name is not found (with did-you-mean), not a fuzzy hit labelled as the typed name', async () => {
+    const out = await text('codegraph_callers', { symbol: 'Calls' });
+    expect(out).toMatch(/Symbol "Calls" not found/);
+    expect(out).toMatch(/Did you mean:/);
+    expect(out).not.toMatch(/Callees of Calls|Callers of Calls/);
+    expect(out).not.toMatch(/\bef\b/);
+  });
+
+  it('callees: missing name does not return another method\'s callees', async () => {
+    const out = await text('codegraph_callees', { symbol: 'Calls' });
+    expect(out).toMatch(/Symbol "Calls" not found/);
+    expect(out).not.toContain('Callees of Calls');
+  });
+
+  it('impact: missing prefix does not substitute a longer name', async () => {
+    const out = await text('codegraph_impact', { symbol: 'callsEf' });
+    expect(out).toMatch(/Symbol "callsEf" not found/);
+    expect(out).toMatch(/Did you mean:.*callsEfOnly/);
+    // Suggestion only — must not claim impact results for the mistyped name.
+    expect(out).not.toMatch(/Impact:|"callsEf" affects|affected/);
+  });
+
+  it('callers: exact name with zero callers stays empty (no case-sibling substitution)', async () => {
+    const out = await text('codegraph_callers', { symbol: 'Fetch' });
+    expect(out).toMatch(/No callers found for "Fetch"/);
+    expect(out).not.toContain('load');
+  });
+
+  it('callers: real exact name still resolves', async () => {
+    const out = await text('codegraph_callers', { symbol: 'ef' });
+    expect(out).toContain('Callers of ef');
+    expect(out).toContain('callsEfOnly');
+    expect(out).toContain('alsoCallsEf');
+  });
+
+  it('findAllSymbols returns no nodes for a fuzzy-only hit', async () => {
+    const findAllSymbols = (handler as any).findAllSymbols.bind(handler);
+    const all = findAllSymbols(cg, 'Calls');
+    expect(all.nodes).toEqual([]);
+    expect(all.note).toMatch(/Did you mean:/);
+  });
+});
+
+describe.skipIf(!HAS_SQLITE || !fs.existsSync(BIN))('no silent fuzzy substitution (#1473) — CLI', () => {
+  let projectRoot: string;
+
+  beforeEach(async () => {
+    projectRoot = tmpRoot('codegraph-1473-cli-');
+    const src = path.join(projectRoot, 'src', 'a', 'b', 'c');
+    fs.mkdirSync(src, { recursive: true });
+    fs.writeFileSync(
+      path.join(src, 'D.java'),
+      `package a.b.c;\n\npublic class D {\n    public void e()  { System.out.println("e"); }\n    public void ef() { System.out.println("ef"); }\n}\n`
+    );
+    fs.writeFileSync(
+      path.join(src, 'Caller.java'),
+      `package a.b.c;\n\npublic class Caller {\n    public void callsEfOnly() { D d = new D(); d.ef(); }\n    public void alsoCallsEf() { D d = new D(); d.ef(); }\n}\n`
+    );
+    fs.writeFileSync(
+      path.join(projectRoot, 'src', 'Fetch.cs'),
+      `public class Torture {\n  public void Fetch() {}\n}\n`
+    );
+    fs.writeFileSync(
+      path.join(projectRoot, 'src', 'fetch.py'),
+      `def fetch():\n    return 1\n\ndef load():\n    return fetch()\n`
+    );
+
+    const CodeGraph = (await import('../src/index')).default;
+    const cg = CodeGraph.initSync(projectRoot);
+    await cg.indexAll();
+    cg.close();
+  });
+
+  afterEach(() => {
+    rmTree(projectRoot);
+  });
+
+  it('callers: fuzzy-only name → not found with did-you-mean (JSON stays empty)', () => {
+    const { stdout } = runCli(['callers', 'Calls', '--json'], projectRoot);
+    // JSON path is only taken on a successful resolve; not-found prints info text.
+    expect(stdout).toMatch(/Symbol "Calls" not found/);
+    expect(stdout).toMatch(/did you mean/i);
+    expect(stdout).not.toMatch(/"name":\s*"ef"/);
+  });
+
+  it('callees: fuzzy-only name → not found', () => {
+    const { stdout } = runCli(['callees', 'Calls', '--json'], projectRoot);
+    expect(stdout).toMatch(/Symbol "Calls" not found/);
+    expect(stdout).not.toMatch(/"name":\s*"ef"/);
+  });
+
+  it('impact: prefix of a real name → not found', () => {
+    const { stdout } = runCli(['impact', 'callsEf', '--json'], projectRoot);
+    expect(stdout).toMatch(/Symbol "callsEf" not found/);
+    expect(stdout).toMatch(/did you mean:.*callsEfOnly/i);
+    // Not a successful JSON impact payload for the fuzzy hit.
+    expect(stdout).not.toMatch(/"affected"\s*:/);
+    expect(stdout).not.toMatch(/"symbol":\s*"callsEf"/);
+  });
+
+  it('callers: exact Fetch with zero callers → empty list, not fetch\'s callers', () => {
+    const { stdout } = runCli(['callers', 'Fetch', '--json'], projectRoot);
+    expect(stdout).toContain('"symbol": "Fetch"');
+    expect(stdout).toMatch(/"callers":\s*\[\s*\]/);
+    expect(stdout).not.toContain('load');
+  });
+
+  it('callers: exact ef still lists real callers', () => {
+    const { stdout } = runCli(['callers', 'ef', '--json'], projectRoot);
+    expect(stdout).toContain('callsEfOnly');
+    expect(stdout).toContain('alsoCallsEf');
+  });
+});

__tests__/symbol-lookup.test.ts

@@ -157,6 +157,26 @@ describe.skipIf(!HAS_SQLITE)('matchesSymbol — module-qualified lookups (#173)'
     expect(matches.length).toBe(0);
   });
 
+  it('findAllSymbols rejects a fuzzy-only bare prefix with a suggestion (#1473)', () => {
+    expect(cg.getNodesByName('run_due')).toEqual([]);
+    expect(cg.searchNodes('run_due').length).toBeGreaterThan(0);
+    const all = findAllSymbols(cg, 'run_due');
+    expect(all.nodes).toEqual([]);
+    expect(all.note).toMatch(/Did you mean:.*run_due_tasks/);
+  });
+
+  it('findAllSymbols rejects an unknown qualifier even when the bare tail exists (#173)', () => {
+    expect(cg.getNodesByName('run').length).toBeGreaterThan(0);
+    expect(findAllSymbols(cg, 'missing::run').nodes).toEqual([]);
+  });
+
+  it('preserves codegraph_node file-basename lookup (#1473)', () => {
+    expect(cg.getNodesByName('stage_apply')).toEqual([]);
+    const matches = findSymbolMatches(cg, 'stage_apply');
+    expect(matches.length).toBeGreaterThan(0);
+    expect(matches[0]!.filePath).toMatch(/configurator\/stage_apply\.rs$/);
+  });
+
   it('codegraph_node with a `file` hint pins an overloaded name to that file', async () => {
     // `run` is defined in BOTH stage_apply.rs and stage_detect.rs. A bare lookup
     // returns both; the `file` hint narrows to the one the caller saw in a trail.
@@ -391,4 +411,15 @@ describe.skipIf(!HAS_SQLITE)('lookupSymbolNodes — the shared path used by call
     const { nodes } = lookupSymbolNodes(cg, 'chart.nonexistent_fn');
     expect(nodes.length).toBe(0);
   });
+
+  it.each(['grou', 'Group'])('rejects fuzzy-only bare name "%s" (#1473)', (symbol) => {
+    expect(cg.getNodesByName(symbol)).toEqual([]);
+    expect(cg.searchNodes(symbol).length).toBeGreaterThan(0);
+    expect(lookupSymbolNodes(cg, symbol)).toEqual({ nodes: [], ambiguous: false });
+  });
+
+  it('rejects an unknown qualifier even when the bare tail exists (#173)', () => {
+    expect(cg.getNodesByName('group').length).toBeGreaterThan(0);
+    expect(lookupSymbolNodes(cg, 'missing.group')).toEqual({ nodes: [], ambiguous: false });
+  });
 });

src/bin/codegraph.ts

@@ -365,6 +365,13 @@ function warn(message: string): void {
   console.log(chalk.yellow(getGlyphs().warn) + ' ' + message);
 }
 
+/** "not found" (+ optional did-you-mean) when no exact symbol matches. */
+function formatSymbolNotFound(symbol: string, fuzzyNames: string[]): string {
+  const suggestions = [...new Set(fuzzyNames.filter((n) => n !== symbol))].slice(0, 3);
+  if (suggestions.length === 0) return `Symbol "${symbol}" not found`;
+  return `Symbol "${symbol}" not found — did you mean: ${suggestions.join(', ')}?`;
+}
+
 /** Compact node shape retained by the CLI's existing JSON lists. */
 function cliNode(node: Node) {
   return { name: node.name, kind: node.kind, filePath: node.filePath, startLine: node.startLine };
@@ -2212,7 +2219,7 @@ for (const direction of ['callers', 'callees'] as const) {
           const limit = parseInt(options.limit || '20', 10);
           const { nodes: targets } = lookupSymbolNodes(cg, symbol);
           if (targets.length === 0) {
-            info(`Symbol "${symbol}" not found`);
+            info(formatSymbolNotFound(symbol, cg.searchNodes(symbol, { limit: 5 }).map((m) => m.node.name)));
             return;
           }
 
@@ -2330,7 +2337,7 @@ program
         const depth = Math.min(Math.max(parseInt(options.depth || '2', 10), 1), 10);
         const { nodes: targets } = lookupSymbolNodes(cg, symbol);
         if (targets.length === 0) {
-          info(`Symbol "${symbol}" not found`);
+          info(formatSymbolNotFound(symbol, cg.searchNodes(symbol, { limit: 5 }).map((m) => m.node.name)));
           return;
         }
 

src/graph/named-symbol-flow.ts

@@ -44,6 +44,10 @@ export { RUST_PATH_PREFIXES, lastQualifierPart, matchesSymbol } from './symbol-l
 /**
  * Find ALL symbols matching a name. Used by callers/callees/impact to aggregate
  * results across all matching symbols (e.g., multiple classes with an `execute` method).
+ *
+ * Exact matches only (#1473): a missing / mistyped name must NOT silently
+ * resolve to the top fuzzy FTS hit under the caller's typed label. Closest
+ * hits may appear in `note` as a did-you-mean hint when `nodes` is empty.
  */
 export function findAllSymbols(cg: CodeGraph, symbol: string): { nodes: Node[]; note: string } {
   // Nix option paths: the declaration is stored as `options.<path>` and
@@ -66,42 +70,57 @@ export function findAllSymbols(cg: CodeGraph, symbol: string): { nodes: Node[];
       return { nodes, note: '' };
     }
   }
-  let results = cg.searchNodes(symbol, { limit: 50 });
 
-  // Mirror the fallback in `findSymbol` for qualified queries — FTS
-  // strips colons, so a module-qualified lookup needs a second pass
-  // by the bare last part.
-  if (results.length === 0 && /[.\/]|::/.test(symbol)) {
-    const tail = lastQualifierPart(symbol);
-    if (tail && tail !== symbol) results = cg.searchNodes(tail, { limit: 50 });
+  const isQualified = /[.\/]|::/.test(symbol);
+  let exactNodes: Node[];
+
+  if (!isQualified) {
+    // Direct index — every exact-name overload, case-sensitive. Avoids FTS
+    // ranking a differently-cased sibling above the real node (#1473 Fetch).
+    exactNodes = cg.getNodesByName(symbol);
+  } else {
+    let results = cg.searchNodes(symbol, { limit: 50 });
+    // Mirror findSymbolMatches — FTS strips colons, so re-search by bare tail.
+    if (results.length === 0) {
+      const tail = lastQualifierPart(symbol);
+      if (tail && tail !== symbol) results = cg.searchNodes(tail, { limit: 50 });
+    }
+    exactNodes = results
+      .filter((r) => matchesSymbol(r.node, symbol))
+      .map((r) => r.node);
   }
 
-  if (results.length === 0) {
-    return { nodes: [], note: '' };
+  if (exactNodes.length === 0) {
+    const fuzzy = cg.searchNodes(symbol, { limit: 5 });
+    const suggestions = [
+      ...new Set(fuzzy.map((r) => r.node.name).filter((n) => n !== symbol)),
+    ].slice(0, 3);
+    const note =
+      suggestions.length > 0
+        ? `\n\n> **Note:** no symbol named "${symbol}". Did you mean: ${suggestions.join(', ')}?`
+        : '';
+    return { nodes: [], note };
   }
 
-  const exactMatches = results.filter(r => matchesSymbol(r.node, symbol));
-
-  if (exactMatches.length <= 1) {
-    const node = exactMatches[0]?.node ?? results[0]!.node;
-    return { nodes: [node], note: '' };
+  if (exactNodes.length === 1) {
+    return { nodes: exactNodes, note: '' };
   }
 
   // Same generated-file down-rank as findSymbol — keeps callers/callees
   // /impact aggregation aligned (a query against "Send" returns the
   // hand-written implementations before the protobuf scaffold).
-  const isGen = cg.generatedFilePredicate(exactMatches.map((r) => r.node.filePath));
-  const ranked = [...exactMatches].sort((a, b) => {
-    const aGen = isGen(a.node.filePath) ? 1 : 0;
-    const bGen = isGen(b.node.filePath) ? 1 : 0;
+  const isGen = cg.generatedFilePredicate(exactNodes.map((n) => n.filePath));
+  const ranked = [...exactNodes].sort((a, b) => {
+    const aGen = isGen(a.filePath) ? 1 : 0;
+    const bGen = isGen(b.filePath) ? 1 : 0;
     return aGen - bGen;
   });
 
-  const locations = ranked.map(r =>
-    `${r.node.kind} at ${r.node.filePath}:${r.node.startLine}`
+  const locations = ranked.map(
+    (n) => `${n.kind} at ${n.filePath}:${n.startLine}`
   );
   const note = `\n\n> **Note:** Aggregated results across ${ranked.length} symbols named "${symbol}": ${locations.join(', ')}`;
-  return { nodes: ranked.map(r => r.node), note };
+  return { nodes: ranked, note };
 }
 
 /** Node kinds that can sit on a call chain. */

src/graph/symbol-lookup.ts

@@ -167,8 +167,8 @@ export function groupDefinitions(
  * The exact-name index is consulted FIRST and is authoritative: it is complete
  * and uncapped, whereas FTS ranks and truncates, and tokenises away `::` — so
  * a qualified query could miss a symbol that exists, or land on whatever
- * happened to rank first. FTS remains as the fallback for the fuzzy cases it is
- * genuinely good at (file basenames, partial names).
+ * happened to rank first. FTS candidates still have to satisfy the matcher;
+ * partial or mistyped names must never select the top fuzzy hit (#1473).
  */
 export function lookupSymbolNodes(cg: SymbolLookupHost, symbol: string): SymbolLookupResult {
   const qualified = isQualifiedSymbol(symbol);
@@ -183,12 +183,9 @@ export function lookupSymbolNodes(cg: SymbolLookupHost, symbol: string): SymbolL
     const exact = hits.filter((n) => matchesSymbol(n, symbol));
     if (exact.length > 0) {
       nodes = exact;
-    } else if (!qualified && hits[0]) {
-      // A bare name with no exact definition may still mean a file basename.
-      nodes = [hits[0]];
     }
-    // A qualified query with no exact match resolves to NOTHING rather than a
-    // misleading fuzzy hit (#173).
+    // Any query with no exact match resolves to NOTHING rather than a
+    // misleading fuzzy hit (#1473; qualified lookups already did this in #173).
   }
 
   if (nodes.length === 0) return { nodes: [], ambiguous: false };

src/mcp/server-instructions.ts

@@ -56,6 +56,7 @@ calls; a grep/read exploration is dozens.
 - **Reading or editing a file/symbol you can name** → put its name or file path in the \`codegraph_explore\` query — it returns that current line-numbered source (safe to \`Edit\` from) with the call path and blast radius attached, so you don't Read it separately. For an overloaded name it returns every matching definition's body in one call.
 - **Need more?** Call \`codegraph_explore\` again with more specific names — treat the source it returns as already Read. Suggested call counts are advisory only, NOT a quota; extra calls are never rejected or rate-limited.
 - Qualified symbol names accept dots, \`::\`, or slashes, including containers whose names contain dots (for example, \`AppWeb.Format.group\`).
+- Named-symbol call paths require exact matches; partial or mistyped names are never silently substituted as flow endpoints. If a graph query reports a missing symbol with did-you-mean suggestions, query the suggested name explicitly.
 
 ## Anti-patterns
 

src/mcp/tools.ts

@@ -2375,7 +2375,7 @@ export class ToolHandler {
 
     const allMatches = this.findAllSymbols(cg, symbol);
     if (allMatches.nodes.length === 0) {
-      return this.textResult(`Symbol "${symbol}" not found in the codebase`);
+      return this.textResult(`Symbol "${symbol}" not found in the codebase${allMatches.note}`);
     }
 
     const { groups, filteredOut } = this.groupDefinitions(allMatches.nodes, fileFilter);
@@ -2456,7 +2456,7 @@ export class ToolHandler {
 
     const allMatches = this.findAllSymbols(cg, symbol);
     if (allMatches.nodes.length === 0) {
-      return this.textResult(`Symbol "${symbol}" not found in the codebase`);
+      return this.textResult(`Symbol "${symbol}" not found in the codebase${allMatches.note}`);
     }
 
     const { groups, filteredOut } = this.groupDefinitions(allMatches.nodes, fileFilter);
@@ -2534,7 +2534,7 @@ export class ToolHandler {
 
     const allMatches = this.findAllSymbols(cg, symbol);
     if (allMatches.nodes.length === 0) {
-      return this.textResult(`Symbol "${symbol}" not found in the codebase`);
+      return this.textResult(`Symbol "${symbol}" not found in the codebase${allMatches.note}`);
     }
 
     const { groups, filteredOut } = this.groupDefinitions(allMatches.nodes, fileFilter);