* The server owns the real list and publishes it at `GET /api/v3` under

 * `extensions["chat.openagents"].parameters.model`. This is the client's copy,

 * kept as data for the same reason the server keeps one: a backend the status

 * line offers, the `--model` flag accepts, and Tab cycles through has to be one

 * list, or the three drift and the CLI offers something the server refuses.

 * line shows and the `--model` flag accepts has to be one list, or the two

 * drift and the CLI offers something the server refuses.

 *

 * Choosing between them is not the client's call today. A coder session runs on

 * a thread, and the inference proxy takes the model from that thread's grant,

 * so this list is what the flag validates against and what the status line

 * names, nothing more.

 *

 * Adding a backend is one entry here and one entry on the server. Nothing else

 * in this package names a backend.

  { id: "gemini-3.7-flash", label: "Gemini 3.7 Flash" },

];

/** The backend a turn uses when nothing named one. */

export const defaultBackend = (): CoderBackend => CODER_BACKENDS[0] as CoderBackend;

/** The backend with this id, or `undefined` when nothing matches. */

export const findBackend = (id: string): CoderBackend | undefined =>

  CODER_BACKENDS.find((backend) => backend.id === id);

/**

 * The next backend after this one, wrapping at the end.

 *

 * Cycling rather than toggling is what makes a third backend data: Tab keeps

 * working without a second key or a menu.

 */

export const nextBackend = (current: CoderBackend): CoderBackend => {

  const index = CODER_BACKENDS.findIndex((backend) => backend.id === current.id);

  return CODER_BACKENDS[(index + 1) % CODER_BACKENDS.length] as CoderBackend;

};

/** Every id, for a flag's error message and its accepted values. */

export const backendIds = (): readonly string[] => CODER_BACKENDS.map((backend) => backend.id);

import { describe, expect, it } from "vitest";

import {

  backendIds,

  CODER_BACKENDS,

  defaultBackend,

  findBackend,

  nextBackend,

} from "../src/coder-backends.js";

import { backendIds, CODER_BACKENDS } from "../src/coder-backends.js";

/**

 * The list three surfaces read.

 * The list two surfaces read.

 *

 * `--model` takes its accepted values from it, the status line takes its label

 * from it, and Tab walks it. These pin the properties those three depend on, so

 * adding a backend stays one entry rather than one entry plus three fixes.

 * `--model` takes its accepted values from it and the status line takes its

 * label from it. These pin the properties those two depend on, so adding a

 * backend stays one entry rather than one entry plus two fixes.

 */

describe("coder backends", () => {

  it("names each backend once", () => {

    }

  });

  it("defaults to the first entry, and finds a backend by the id the server takes", () => {

    expect(defaultBackend()).toBe(CODER_BACKENDS[0]);

    expect(findBackend("gemini-3.7-flash")?.label).toBe("Gemini 3.7 Flash");

    expect(findBackend("gpt-4")).toBeUndefined();

  });

  it("reaches every backend by cycling, and returns to the start", () => {

    const seen: string[] = [];

    let current = defaultBackend();

    for (let step = 0; step < CODER_BACKENDS.length; step += 1) {

      current = nextBackend(current);

      seen.push(current.id);

    }

    expect(new Set(seen)).toEqual(new Set(backendIds()));

    expect(current).toBe(defaultBackend());

  });

  it("publishes ids the chat API's own enum lists", () => {

    // These are the values `POST /api/v3/chat/turns` accepts as `model`, so a

    // change here without the matching server change is a refusal at runtime.

import { EventEmitter } from "node:events";

import { describe, expect, it } from "vitest";

import { CODER_BACKENDS, defaultBackend } from "../src/coder-backends.js";

import { CODER_BACKENDS } from "../src/coder-backends.js";

import { CoderSession, type ReplyChunk, type ReplySource } from "../src/coder-session.js";

import { CoderTaskRegistry } from "../src/coder-tasks.js";

import { runCoderUi } from "../src/coder-ui.js";

    it("wraps around, so every backend is reachable from one key", async () => {

      const { session } = await driveSwitchable(CODER_BACKENDS.map(() => "\t"));

      expect(session.snapshot().model).toBe(defaultBackend().label);

      expect(session.snapshot().model).toBe(CODER_BACKENDS[0]?.label);

    });

    it("does not leave a tab in the composer", async () => {

    "allowed: intentional, permanent exceptions. Each one needs a written reason.",

    "Rationale: docs/quality/uncalled-production-symbols.md",

    "2026-08-03: the guard counted names in comments and strings as callers; fixing that revealed 171 findings it had been blind to. They are inherited debt, not approvals, and the list may only shrink.",

    "2026-08-23: clean origin/main at df62c1fe already failed the guard with 47 pre-existing findings; the currently flagged refs recorded below are inherited debt, not approvals, and the two stale ledger entries were pruned separately.",

    "2026-08-23: running the coder on its own thread took the model choice from the client, so coder-backends' defaultBackend, findBackend, and nextBackend lost their production callers while their tests stayed. Inherited debt: either the proxy takes a client-named model again, or the picker and its tests go."

    "2026-08-23: clean origin/main at df62c1fe already failed the guard with 47 pre-existing findings; the currently flagged refs recorded below are inherited debt, not approvals, and the two stale ledger entries were pruned separately."

  ],

  "baselinedAt": "2026-07-31",

  "inheritedDebt": [

    "packages/openagents-cli/src/api-transport.ts#networkPolicyTestLoopbackLayer",

    "packages/openagents-cli/src/browser-launcher.ts#browserLauncherTestLayer",

    "packages/openagents-cli/src/cli.ts#runCliWith",

    "packages/openagents-cli/src/coder-backends.ts#defaultBackend",

    "packages/openagents-cli/src/coder-backends.ts#findBackend",

    "packages/openagents-cli/src/coder-backends.ts#nextBackend",

    "packages/openagents-cli/src/credential-store.ts#credentialStoreTestFileLayer",

    "packages/openagents-cli/src/credential-store.ts#credentialStoreUnavailableLayer",

    "packages/openagents-cli/src/device-authorization-store.ts#pendingDeviceAuthorizationStoreTestLayer",