chore: import upstream snapshot with attribution

@omniroute/opencode-plugin/tests/usable-combo.test.ts

@@ -0,0 +1,85 @@
+/**
+ * Regression tests for `isUsableCombo` (release/v3.8.2 code review, finding C1).
+ *
+ * The combo member refs returned by `/api/combos` do NOT carry a separate
+ * `providerId` field — OmniRoute's `normalizeComboRecord` folds the provider
+ * id INTO the full model string (e.g. "cc/claude-opus-4-7"). The previous
+ * implementation read `step.providerId` (always `undefined`), so the
+ * `usableOnly` combo filter silently never dropped anything. These tests pin
+ * the corrected behavior: the verdict is derived from the `step.model` prefix,
+ * mirroring `isUsableRawModelId`'s subtract-filter semantics.
+ */
+
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { isUsableCombo, type OmniRouteRawCombo } from "../src/index.js";
+
+/** Build a `usable` set bundle for the tests. */
+function buildUsable(opts: { aliases?: string[]; canonicals?: string[]; known?: string[] }): {
+  aliases: Set<string>;
+  canonicals: Set<string>;
+  knownAliases: Set<string>;
+} {
+  return {
+    aliases: new Set(opts.aliases ?? []),
+    canonicals: new Set(opts.canonicals ?? []),
+    // knownAliases is the union of every prefix the universe is aware of —
+    // usable or not. Default to including the usable aliases too.
+    knownAliases: new Set([...(opts.known ?? []), ...(opts.aliases ?? [])]),
+  };
+}
+
+function combo(models: OmniRouteRawCombo["models"]): OmniRouteRawCombo {
+  return { id: "c1", name: "Test Combo", models };
+}
+
+test("isUsableCombo: member with a usable alias prefix → keep", () => {
+  const usable = buildUsable({ aliases: ["cc"], known: ["cc", "dead"] });
+  const c = combo([{ kind: "model", model: "cc/claude-opus-4-7" }]);
+  assert.equal(isUsableCombo(c, usable), true);
+});
+
+test("isUsableCombo: all members known-but-NOT-usable → drop (the C1 regression)", () => {
+  // Before the fix this returned true unconditionally because step.providerId
+  // was always undefined. Now the known-but-unusable "dead" prefix is dropped.
+  const usable = buildUsable({ aliases: ["cc"], known: ["cc", "dead"] });
+  const c = combo([
+    { kind: "model", model: "dead/legacy-model" },
+    { kind: "model", model: "dead/another" },
+  ]);
+  assert.equal(isUsableCombo(c, usable), false);
+});
+
+test("isUsableCombo: unknown prefix → keep (cannot prove unroutable)", () => {
+  const usable = buildUsable({ aliases: ["cc"], known: ["cc", "dead"] });
+  const c = combo([{ kind: "model", model: "agentrouter/mystery" }]);
+  assert.equal(isUsableCombo(c, usable), true);
+});
+
+test("isUsableCombo: mixed non-usable + usable member → keep", () => {
+  const usable = buildUsable({ aliases: ["cc"], known: ["cc", "dead"] });
+  const c = combo([
+    { kind: "model", model: "dead/legacy" },
+    { kind: "model", model: "cc/claude-opus-4-7" },
+  ]);
+  assert.equal(isUsableCombo(c, usable), true);
+});
+
+test("isUsableCombo: zero members → keep", () => {
+  const usable = buildUsable({ aliases: ["cc"], known: ["cc"] });
+  assert.equal(isUsableCombo(combo([]), usable), true);
+  assert.equal(isUsableCombo(combo(undefined), usable), true);
+});
+
+test("isUsableCombo: only combo-ref steps (no resolvable model) → keep", () => {
+  const usable = buildUsable({ aliases: ["cc"], known: ["cc", "dead"] });
+  const c = combo([{ kind: "combo-ref", comboName: "nested" }]);
+  assert.equal(isUsableCombo(c, usable), true);
+});
+
+test("isUsableCombo: usable canonical prefix → keep", () => {
+  const usable = buildUsable({ canonicals: ["anthropic"], known: ["anthropic", "dead"] });
+  const c = combo([{ kind: "model", model: "anthropic/claude-opus-4-7" }]);
+  assert.equal(isUsableCombo(c, usable), true);
+});