fix(extraction): map PHP include/require to file→file dependency edges (#660) (#663)

PHP's importTypes only captured namespace_use_declaration, so
include/require(_once) — the dependency mechanism in procedural and
script-style PHP — never produced edges. callers, impact, and trace
missed the entire file-include graph; only namespace `use` became a
dependency edge.

Capture the four include/require expression types and emit file→file
imports edges, reusing the path-based resolution that C/C++ #include
already goes through. Only static string-literal paths are resolved
(relative to the including file); dynamic forms (include $var,
require __DIR__ . '/x', interpolated strings) are skipped.

Include PATHS are distinguished from namespace `use` symbols by shape: a
path contains '/' or '.', which PHP identifiers and FQNs never do. A
path-shaped include that doesn't resolve to a known project file is left
unresolved and does NOT fall back to the symbol name-matcher, which would
otherwise mis-connect "inc/db.php" to an unrelated db.php elsewhere — a
wrong edge is worse than a missing one.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Colby McHenry <me@colbymchenry.com>

src/resolution/index.ts

@@ -17,7 +17,7 @@ import {
   ImportMapping,
 } from './types';
 import { matchReference, sameLanguageFamily, crossesKnownFamily } from './name-matcher';
-import { resolveViaImport, resolveJvmImport, extractImportMappings, extractReExports, loadCppIncludeDirs } from './import-resolver';
+import { resolveViaImport, resolveJvmImport, extractImportMappings, extractReExports, loadCppIncludeDirs, isPhpIncludePathRef } from './import-resolver';
 import { detectFrameworks } from './frameworks';
 import { synthesizeCallbackEdges } from './callback-synthesizer';
 import { loadProjectAliases, type AliasMap } from './path-aliases';
@@ -666,6 +666,18 @@ export class ReferenceResolver {
       candidates.push(importResult);
     }
 
+    // PHP include/require paths resolve to files via import resolution only.
+    // If that didn't find the file, do NOT fall back to the symbol
+    // name-matcher — it would mis-connect e.g. "inc/db.php" to an unrelated
+    // db.php elsewhere in the tree (a wrong edge is worse than none, #660).
+    if (isPhpIncludePathRef(ref)) {
+      return candidates.length > 0
+        ? candidates.reduce((best, curr) =>
+            curr.confidence > best.confidence ? curr : best
+          )
+        : null;
+    }
+
     // Strategy 3: Try name matching
     const nameResult = this.gateLanguage(matchReference(ref, this.context), ref);
     if (nameResult) {