test+feat: add cargo workspace crate resolution for rust resolver (#151)

* test+feat: add cargo workspace crate resolution for rust resolver

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Co-authored-by: miketheman <529516+miketheman@users.noreply.github.com>

* perf: cache cargo workspace map during rust resolution

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* feat(rust): expand cargo workspace member globs and trust workspace hits

- Parse glob entries in `[workspace].members` (e.g. `crates/*`,
  `helix-*`) via picomatch against a new optional
  `ResolutionContext.listDirectories` so workspaces that don't
  enumerate every member are covered. Implementation walks the
  static-prefix subtree with a depth cap and skips `target`,
  `node_modules`, `.git`, etc.
- Bump Pattern 4's confidence to 0.95 when the workspace map
  produces a hit. The cargo manifest gives an unambiguous
  crate-name -> crate-root mapping, so workspace-driven module
  resolution should beat name-matcher's self-file matches
  (otherwise every file with `use foo::...` self-resolves at 0.7
  and the cross-crate edge never materializes).
- Validated against astral-sh/uv (`members = ["crates/*"]`,
  67 crates, 567 .rs files): 1,969 cross-crate `imports` edges
  reaching 60 distinct member lib.rs files, up from 0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Colby McHenry <me@colbymchenry.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/resolution/frameworks/rust.ts

@@ -7,6 +7,17 @@
 import { Node } from '../../types';
 import { FrameworkResolver, UnresolvedRef, ResolvedRef, ResolutionContext } from '../types';
 import { stripCommentsForRegex } from '../strip-comments';
+import { getCargoWorkspaceCrateMap } from './cargo-workspace';
+
+const cargoWorkspaceMapCache = new WeakMap<ResolutionContext, Map<string, string>>();
+
+function getCachedCargoWorkspaceCrateMap(context: ResolutionContext): Map<string, string> {
+  const cached = cargoWorkspaceMapCache.get(context);
+  if (cached) return cached;
+  const map = getCargoWorkspaceCrateMap(context);
+  cargoWorkspaceMapCache.set(context, map);
+  return map;
+}
 
 export const rustResolver: FrameworkResolver = {
   name: 'rust',
@@ -61,10 +72,15 @@ export const rustResolver: FrameworkResolver = {
     if (/^[a-z_]+$/.test(ref.referenceName)) {
       const result = resolveModule(ref.referenceName, context);
       if (result) {
+        // Workspace-manifest hits are an exact crate-name -> crate-root
+        // mapping straight from Cargo.toml, so we trust them above
+        // name-matcher self-file matches (which otherwise win at 0.7
+        // because every file containing `use foo::...` has its own
+        // import node named `foo`).
         return {
           original: ref,
-          targetNodeId: result,
-          confidence: 0.6,
+          targetNodeId: result.targetId,
+          confidence: result.fromWorkspace ? 0.95 : 0.6,
           resolvedBy: 'framework',
         };
       }
@@ -191,25 +207,32 @@ function resolveByNameAndKind(
   return kindFiltered[0]!.id;
 }
 
-function resolveModule(name: string, context: ResolutionContext): string | null {
+interface ModuleResolution {
+  targetId: string;
+  fromWorkspace: boolean;
+}
+
+function resolveModule(name: string, context: ResolutionContext): ModuleResolution | null {
   // Rust modules can be either mod.rs in a directory or name.rs
-  const possiblePaths = [
-    `src/${name}.rs`,
-    `src/${name}/mod.rs`,
+  const localPaths = [`src/${name}.rs`, `src/${name}/mod.rs`];
+
+  const workspaceCrates = getCachedCargoWorkspaceCrateMap(context);
+  const cratePath = workspaceCrates.get(name);
+  const workspacePaths = cratePath
+    ? [`${cratePath}/src/lib.rs`, `${cratePath}/src/main.rs`]
+    : [];
+
+  const candidates: Array<{ path: string; fromWorkspace: boolean }> = [
+    ...localPaths.map((path) => ({ path, fromWorkspace: false })),
+    ...workspacePaths.map((path) => ({ path, fromWorkspace: true })),
   ];
 
-  for (const modPath of possiblePaths) {
-    if (context.fileExists(modPath)) {
-      const nodes = context.getNodesInFile(modPath);
-      const modNode = nodes.find((n) => n.kind === 'module');
-      if (modNode) {
-        return modNode.id;
-      }
-      // If no explicit module node, return the first node in the file
-      if (nodes.length > 0) {
-        return nodes[0]!.id;
-      }
-    }
+  for (const { path: modPath, fromWorkspace } of candidates) {
+    if (!context.fileExists(modPath)) continue;
+    const nodes = context.getNodesInFile(modPath);
+    const modNode = nodes.find((n) => n.kind === 'module');
+    if (modNode) return { targetId: modNode.id, fromWorkspace };
+    if (nodes.length > 0) return { targetId: nodes[0]!.id, fromWorkspace };
   }
 
   return null;