feat(agent): add free-text vehicle resolver

Mirrors resolveSite: id, then QR code, then exact description, then
substring — and ambiguity is reported, never guessed. Picking the wrong
vehicle silently attributes fuel spend to the wrong machine.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/lib/agent/resolve.test.ts

@@ -1,5 +1,10 @@
 import { describe, it, expect } from "vitest";
-import { resolveSite, type SiteRef } from "./resolve";
+import {
+  resolveSite,
+  resolveVehicle,
+  type SiteRef,
+  type VehicleRef,
+} from "./resolve";
 
 const SITES: SiteRef[] = [
   { id: "aaa111", name: "The Hills", projectCode: "C26/09" },
@@ -67,4 +72,49 @@ describe("resolveSite", () => {
     const r = resolveSite("anything", []);
     expect(r.kind).toBe("none");
   });
-});
+});
+const VEHICLES: VehicleRef[] = [
+  { id: "v1", description: "Center Point Grader", qrCodeId: "1626", projectCode: "C26/09" },
+  { id: "v2", description: "Isuzu MY85HGGP", qrCodeId: "1936", projectCode: "C26/09" },
+  { id: "v3", description: "TLB centre point", qrCodeId: "2201", projectCode: "C26/09" },
+];
+
+describe("resolveVehicle", () => {
+  it("matches an exact record id", () => {
+    const r = resolveVehicle("v2", VEHICLES);
+    expect(r.kind).toBe("exact");
+    if (r.kind === "exact") expect(r.vehicle.id).toBe("v2");
+  });
+
+  it("matches a QR code", () => {
+    const r = resolveVehicle("1626", VEHICLES);
+    expect(r.kind).toBe("exact");
+    if (r.kind === "exact") expect(r.vehicle.id).toBe("v1");
+  });
+
+  it("matches a full description case-insensitively", () => {
+    const r = resolveVehicle("center point grader", VEHICLES);
+    expect(r.kind).toBe("exact");
+    if (r.kind === "exact") expect(r.vehicle.id).toBe("v1");
+  });
+
+  it("matches a unique substring", () => {
+    const r = resolveVehicle("isuzu", VEHICLES);
+    expect(r.kind).toBe("exact");
+    if (r.kind === "exact") expect(r.vehicle.id).toBe("v2");
+  });
+
+  it("reports ambiguity rather than guessing", () => {
+    const r = resolveVehicle("point", VEHICLES);
+    expect(r.kind).toBe("ambiguous");
+    if (r.kind === "ambiguous") expect(r.matches.length).toBe(2);
+  });
+
+  it("returns none for no match", () => {
+    expect(resolveVehicle("helicopter", VEHICLES).kind).toBe("none");
+  });
+
+  it("returns none for an empty query", () => {
+    expect(resolveVehicle("  ", VEHICLES).kind).toBe("none");
+  });
+});

src/lib/agent/resolve.ts

@@ -50,4 +50,54 @@ export function resolveSite(query: string, sites: SiteRef[]): ResolveSiteResult
 /** Human-readable disambiguation line for an ambiguous result. */
 export function describeAmbiguity(matches: SiteRef[]): string {
   return matches.map((m) => `${m.name} (${m.projectCode})`).join(", ");
+}
+
+export interface VehicleRef {
+  id: string;
+  description: string;
+  qrCodeId: string;
+  projectCode: string;
+}
+
+export type ResolveVehicleResult =
+  | { kind: "exact"; vehicle: VehicleRef }
+  | { kind: "ambiguous"; matches: VehicleRef[] }
+  | { kind: "none" };
+
+/**
+ * Free-text vehicle lookup. Mirrors resolveSite: id, then QR code, then
+ * exact description, then substring — and ambiguity is reported, never
+ * guessed. Picking the wrong vehicle silently attributes fuel spend to
+ * the wrong machine.
+ */
+export function resolveVehicle(
+  query: string,
+  vehicles: VehicleRef[],
+): ResolveVehicleResult {
+  const q = query.trim().toLowerCase();
+  if (!q) return { kind: "none" };
+
+  const byId = vehicles.find((v) => v.id === query.trim());
+  if (byId) return { kind: "exact", vehicle: byId };
+
+  const byQr = vehicles.filter((v) => v.qrCodeId.toLowerCase() === q);
+  if (byQr.length === 1) return { kind: "exact", vehicle: byQr[0] };
+  if (byQr.length > 1) return { kind: "ambiguous", matches: byQr };
+
+  const byDesc = vehicles.filter((v) => v.description.toLowerCase() === q);
+  if (byDesc.length === 1) return { kind: "exact", vehicle: byDesc[0] };
+  if (byDesc.length > 1) return { kind: "ambiguous", matches: byDesc };
+
+  const bySub = vehicles.filter((v) =>
+    v.description.toLowerCase().includes(q),
+  );
+  if (bySub.length === 1) return { kind: "exact", vehicle: bySub[0] };
+  if (bySub.length > 1) return { kind: "ambiguous", matches: bySub };
+
+  return { kind: "none" };
+}
+
+/** Human-readable disambiguation line for an ambiguous vehicle result. */
+export function describeVehicleAmbiguity(matches: VehicleRef[]): string {
+  return matches.map((m) => `${m.description} (QR ${m.qrCodeId})`).join(", ");
 }