feat(app): rank combobox options by word-boundary match quality

Introduce a shared scoreMatch utility that tiers matches by
word-boundary vs mid-word offset, and use it to rank combobox
options so e.g. "py" prefers "a/py" over "happy".

packages/app/src/components/ui/combobox-options.test.ts

@@ -88,6 +88,39 @@ describe("filterAndRankComboboxOptions", () => {
   it("returns empty when nothing matches", () => {
     expect(filterAndRankComboboxOptions(options, "zzz")).toEqual([]);
   });
+
+  it("ranks word-boundary matches above mid-word substring matches", () => {
+    const items = [
+      { id: "happy", label: "happy" },
+      { id: "a/py", label: "a/py" },
+    ];
+    const result = filterAndRankComboboxOptions(items, "py");
+    expect(result.map((o) => o.id)).toEqual(["a/py", "happy"]);
+  });
+
+  it("interleaves mixed branches and PRs by match quality", () => {
+    const items = [
+      { id: "branch:feat/api-login", label: "feat/api-login" },
+      { id: "branch:feat/pi-direct-sdk", label: "feat/pi-direct-sdk" },
+      { id: "github-pr:202", label: "#202 feat(server): replace Pi ACP with direct SDK provider" },
+      { id: "github-pr:355", label: "#355 feat: add LaTeX math formula rendering" },
+    ];
+    const result = filterAndRankComboboxOptions(items, "pi");
+    expect(result.map((o) => o.id)).toEqual([
+      "branch:feat/pi-direct-sdk",
+      "github-pr:202",
+      "branch:feat/api-login",
+    ]);
+  });
+
+  it("ranks PR-number matches via word-boundary on #", () => {
+    const items = [
+      { id: "github-pr:202", label: "#202 some title" },
+      { id: "github-pr:1202", label: "#1202 another title" },
+    ];
+    const result = filterAndRankComboboxOptions(items, "202");
+    expect(result.map((o) => o.id)).toEqual(["github-pr:202", "github-pr:1202"]);
+  });
 });
 
 describe("combobox above-search ordering", () => {

packages/app/src/components/ui/combobox-options.ts

@@ -1,3 +1,5 @@
+import { compareMatchScores, type MatchScore, scoreMatch } from "../../utils/score-match";
+
 export type ComboboxOptionKind = "directory" | "file";
 
 export interface ComboboxOptionModel {
@@ -7,6 +9,23 @@ export interface ComboboxOptionModel {
   kind?: ComboboxOptionKind;
 }
 
+const DESCRIPTION_FALLBACK_TIER = 99;
+
+function scoreOption(opt: ComboboxOptionModel, search: string): MatchScore | null {
+  const labelScore = scoreMatch(search, opt.label);
+  const idScore = scoreMatch(search, opt.id);
+  let best: MatchScore | null = null;
+  if (labelScore) best = labelScore;
+  if (idScore && (!best || compareMatchScores(idScore, best) < 0)) {
+    best = idScore;
+  }
+  if (best) return best;
+  if (opt.description && opt.description.toLowerCase().includes(search)) {
+    return { tier: DESCRIPTION_FALLBACK_TIER, offset: 0 };
+  }
+  return null;
+}
+
 export interface BuildVisibleComboboxOptionsInput {
   options: ComboboxOptionModel[];
   searchQuery: string;
@@ -40,21 +59,17 @@ export function filterAndRankComboboxOptions(
   search: string,
 ): ComboboxOptionModel[] {
   if (!search) return options;
-  return options
-    .filter(
-      (opt) =>
-        opt.label.toLowerCase().includes(search) ||
-        opt.id.toLowerCase().includes(search) ||
-        opt.description?.toLowerCase().includes(search),
-    )
-    .sort((a, b) => {
-      const aPrefix =
-        a.label.toLowerCase().startsWith(search) || a.id.toLowerCase().startsWith(search);
-      const bPrefix =
-        b.label.toLowerCase().startsWith(search) || b.id.toLowerCase().startsWith(search);
-      if (aPrefix !== bPrefix) return aPrefix ? -1 : 1;
-      return 0;
-    });
+  const scored: { opt: ComboboxOptionModel; score: MatchScore }[] = [];
+  for (const opt of options) {
+    const score = scoreOption(opt, search);
+    if (score) scored.push({ opt, score });
+  }
+  scored.sort((a, b) => {
+    const cmp = compareMatchScores(a.score, b.score);
+    if (cmp !== 0) return cmp;
+    return a.opt.label.localeCompare(b.opt.label);
+  });
+  return scored.map((entry) => entry.opt);
 }
 
 export function buildVisibleComboboxOptions(