Code tab: resolve bare-filename file refs when basename is unique

packages/client/src/ui/lineRef.test.ts

@@ -193,4 +193,48 @@ describe("resolveLineRefPath", () => {
       }),
     ).toBe("nested/src/app.ts");
   });
+
+  it("resolves a bare filename whose basename is unique in the repo", () => {
+    expect(
+      resolveLineRefPath({
+        rawPath: "Main.hs",
+        repoRoot,
+        cwd: repoRoot,
+        repoPaths,
+      }),
+    ).toBe("packages/a/src/Main.hs");
+  });
+
+  it("returns null when the basename is ambiguous", () => {
+    expect(
+      resolveLineRefPath({
+        rawPath: "app.ts",
+        repoRoot,
+        cwd: repoRoot,
+        repoPaths,
+      }),
+    ).toBeNull();
+  });
+
+  it("falls back to basename when a slash-containing path doesn't match", () => {
+    expect(
+      resolveLineRefPath({
+        rawPath: "wrong/Main.hs",
+        repoRoot,
+        cwd: repoRoot,
+        repoPaths,
+      }),
+    ).toBe("packages/a/src/Main.hs");
+  });
+
+  it("prefers an exact path candidate over the basename fallback", () => {
+    expect(
+      resolveLineRefPath({
+        rawPath: "src/app.ts",
+        repoRoot,
+        cwd: repoRoot,
+        repoPaths,
+      }),
+    ).toBe("src/app.ts");
+  });
 });

packages/client/src/ui/lineRef.ts

@@ -104,7 +104,13 @@ function hasRefBoundary(text: string, index: number): boolean {
  *    falls back to repo-relative interpretation only.
  *  - `repoPaths`: live `fsListAll` paths — repo-relative, no leading
  *    `/`. The resolver only returns a path that's actually in this
- *    set. */
+ *    set.
+ *
+ *  When path-based candidates miss, falls back to a basename match —
+ *  compiler output often prints just `Foo.hs:42` without the
+ *  `src/lib/` prefix (#898). The fallback only fires when the
+ *  basename is unique in the repo; ambiguous matches stay null since
+ *  opening the wrong file is worse than the toast. */
 export function resolveLineRefPath(args: {
   rawPath: string;
   repoRoot: string;
@@ -115,7 +121,27 @@ export function resolveLineRefPath(args: {
   for (const candidate of candidates(args)) {
     if (set.has(candidate)) return candidate;
   }
-  return null;
+  return resolveByBasename(args.rawPath, args.repoPaths);
+}
+
+function resolveByBasename(
+  rawPath: string,
+  repoPaths: readonly string[],
+): string | null {
+  const target = basename(rawPath);
+  if (target === "") return null;
+  let unique: string | null = null;
+  for (const p of repoPaths) {
+    if (basename(p) !== target) continue;
+    if (unique !== null) return null;
+    unique = p;
+  }
+  return unique;
+}
+
+function basename(path: string): string {
+  const i = path.lastIndexOf("/");
+  return i < 0 ? path : path.slice(i + 1);
 }
 
 function* candidates(args: {

packages/tests/features/file-ref-link.feature

@@ -25,6 +25,17 @@ Feature: File-ref autolinking in terminal
     And I trigger the terminal file-ref link "range.txt:2-4"
     Then the selected file should show content "three"
 
+  Scenario: Bare filename resolves when its basename is unique in the repo
+    When I run "git init /tmp/kolu-file-ref-898 && cd /tmp/kolu-file-ref-898"
+    And I run "git commit --allow-empty -m init"
+    And I run "mkdir -p src/lib && printf 'alpha\nbeta\ngamma\n' > src/lib/notes.txt"
+    And I run "echo 'see notes.txt:2 for the line'"
+    And I trigger the terminal file-ref link "notes.txt:2"
+    Then the right panel should be visible
+    And the Code tab should be active
+    And the Code tab mode should be "browse"
+    And the selected file should show content "beta"
+
   Scenario: Re-clicking the same file-ref after closing the panel re-selects the line
     When I run "git init /tmp/kolu-file-ref-861-reclick && cd /tmp/kolu-file-ref-861-reclick"
     And I run "git commit --allow-empty -m init"