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fix: forward model variants to opencode prompt body #15

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fix: forward model variants to opencode prompt body #15

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86bffee
fix: forward model variants to opencode prompt body
AveryanAlex Jun 12, 2026
0396c46
fix: remove unsupported shell variant option
AveryanAlex Jun 12, 2026
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7 changes: 3 additions & 4 deletions src/helpers.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -64,15 +64,14 @@ export function setModelDefaults(providerID?: string, modelID?: string): void {
export function applyModelDefaults(
providerID?: string,
modelID?: string,
variant?: string,
): { providerID: string; modelID: string; variant?: string } | undefined {
): { providerID: string; modelID: string } | undefined {
// Explicit params take priority
if (providerID && modelID) {
return { providerID, modelID, ...(variant ? { variant } : {}) };
return { providerID, modelID };
}
// Fall back to env-var defaults
if (_defaultProviderID && _defaultModelID) {
return { providerID: _defaultProviderID, modelID: _defaultModelID, ...(variant ? { variant } : {}) };
return { providerID: _defaultProviderID, modelID: _defaultModelID };
}
// No defaults available — let the server decide
return undefined;
Expand Down
14 changes: 8 additions & 6 deletions src/tools/message.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -104,8 +104,9 @@ export function registerMessageTools(
const body: Record<string, unknown> = {
parts: [{ type: "text", text }],
};
const model = applyModelDefaults(providerID, modelID, variant);
const model = applyModelDefaults(providerID, modelID);
if (model) body.model = model;
if (variant) body.variant = variant;
if (agent) body.agent = agent;
if (noReply !== undefined) body.noReply = noReply;
if (system) body.system = system;
Expand Down Expand Up @@ -155,8 +156,9 @@ export function registerMessageTools(
const body: Record<string, unknown> = {
parts: [{ type: "text", text }],
};
const model = applyModelDefaults(providerID, modelID, variant);
const model = applyModelDefaults(providerID, modelID);
if (model) body.model = model;
if (variant) body.variant = variant;
if (agent) body.agent = agent;
await client.post(`/session/${sessionId}/prompt_async`, body, { directory });
return toolResult(
Expand Down Expand Up @@ -202,8 +204,9 @@ export function registerMessageTools(
arguments: args ?? "",
};
if (agent) body.agent = agent;
const cmdModel = applyModelDefaults(providerID, modelID, variant);
const cmdModel = applyModelDefaults(providerID, modelID);
if (cmdModel) body.model = cmdModel;
if (variant) body.variant = variant;
const result = await client.post(
`/session/${sessionId}/command`,
body,
Expand All @@ -225,13 +228,12 @@ export function registerMessageTools(
agent: z.string().describe("Agent to use for the shell command"),
providerID: z.string().optional().describe("Provider ID"),
modelID: z.string().optional().describe("Model ID"),
variant: z.string().optional().describe("Model variant"),
directory: directoryParam,
},
async ({ sessionId, command, agent, providerID, modelID, variant, directory }) => {
async ({ sessionId, command, agent, providerID, modelID, directory }) => {
try {
const body: Record<string, unknown> = { command, agent };
const shellModel = applyModelDefaults(providerID, modelID, variant);
const shellModel = applyModelDefaults(providerID, modelID);
if (shellModel) body.model = shellModel;
const result = await client.post(
`/session/${sessionId}/shell`,
Expand Down
15 changes: 10 additions & 5 deletions src/tools/workflow.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -261,8 +261,9 @@ export function registerWorkflowTools(
const body: Record<string, unknown> = {
parts: [{ type: "text", text: prompt }],
};
const model = applyModelDefaults(providerID, modelID, variant);
const model = applyModelDefaults(providerID, modelID);
if (model) body.model = model;
if (variant) body.variant = variant;
if (agent) body.agent = agent;
if (system) body.system = system;

Expand Down Expand Up @@ -308,8 +309,9 @@ export function registerWorkflowTools(
const body: Record<string, unknown> = {
parts: [{ type: "text", text: prompt }],
};
const model = applyModelDefaults(providerID, modelID, variant);
const model = applyModelDefaults(providerID, modelID);
if (model) body.model = model;
if (variant) body.variant = variant;
if (agent) body.agent = agent;

const response = await client.post(
Expand Down Expand Up @@ -607,10 +609,11 @@ export function registerWorkflowTools(
};
// Use the specified model, or let the provider pick its default
if (modelID) {
body.model = { providerID: providerId, modelID, ...(variant ? { variant } : {}) };
body.model = { providerID: providerId, modelID };
} else {
body.providerID = providerId;
}
if (variant) body.variant = variant;

const response = await client.post(
`/session/${sessionId}/message`,
Expand Down Expand Up @@ -688,8 +691,9 @@ export function registerWorkflowTools(
parts: [{ type: "text", text: prompt }],
noReply: false,
};
const model = applyModelDefaults(providerID, modelID, variant);
const model = applyModelDefaults(providerID, modelID);
if (model) body.model = model;
if (variant) body.variant = variant;
if (agent) body.agent = agent;

await client.post(`/session/${sid}/message`, body, { directory });
Expand Down Expand Up @@ -802,8 +806,9 @@ export function registerWorkflowTools(
parts: [{ type: "text", text: prompt }],
noReply: false,
};
const model = applyModelDefaults(providerID, modelID, variant);
const model = applyModelDefaults(providerID, modelID);
if (model) body.model = model;
if (variant) body.variant = variant;
if (agent) body.agent = agent;

await client.post(`/session/${sid}/message`, body, { directory });
Expand Down
86 changes: 84 additions & 2 deletions tests/tools.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -28,15 +28,16 @@ function createMockClient(overrides: Record<string, unknown> = {}) {
// ─── Tool registration capture ───────────────────────────────────────────

function captureTools(registerFn: (server: McpServer, client: OpenCodeClient) => void) {
const tools = new Map<string, { description: string; handler: Function }>();
const tools = new Map<string, { description: string; schema: unknown; handler: Function }>();
const mockServer = {
tool: vi.fn((...args: unknown[]) => {
// Handle both 4-arg (name, desc, schema, handler) and
// 5-arg (name, desc, schema, annotations, handler) forms
const name = args[0] as string;
const description = args[1] as string;
const schema = args[2];
const handler = args[args.length - 1] as Function;
tools.set(name, { description, handler });
tools.set(name, { description, schema, handler });
}),
} as unknown as McpServer;
const mockClient = createMockClient();
Expand Down Expand Up @@ -103,6 +104,17 @@ describe("Tool registration", () => {
});
});

describe("registerMessageTools", () => {
it("does not expose unsupported variant parameter on shell execution", () => {
const { tools } = captureTools(registerMessageTools);
const shell = tools.get("opencode_shell_execute")!;
const schema = shell.schema as Record<string, unknown>;
expect(schema).toHaveProperty("providerID");
expect(schema).toHaveProperty("modelID");
expect(schema).not.toHaveProperty("variant");
});
});

describe("registerFileTools", () => {
it("registers 6 file tools", () => {
const { tools } = captureTools(registerFileTools);
Expand Down Expand Up @@ -230,6 +242,19 @@ describe("Tool handlers", () => {
expect(body.model).toEqual({ providerID: "anthropic", modelID: "claude-3" });
});

it("sends variant as a top-level prompt field", async () => {
await handler({
prompt: "test",
providerID: "openai",
modelID: "gpt-5.4",
variant: "xhigh",
});
const [, body] = (mockClient.post as ReturnType<typeof vi.fn>).mock.calls[1];
expect(body.model).toEqual({ providerID: "openai", modelID: "gpt-5.4" });
expect(body.model).not.toHaveProperty("variant");
expect(body.variant).toBe("xhigh");
});

it("includes agent when set", async () => {
await handler({ prompt: "test", agent: "build" });
const [, body] = (mockClient.post as ReturnType<typeof vi.fn>).mock.calls[1];
Expand Down Expand Up @@ -335,6 +360,34 @@ describe("Tool handlers", () => {
expect(result.content[0].text).toContain("Sure, here you go");
expect(result.content[0].text).not.toContain("WARNING");
});

it("sends variant as a top-level field", async () => {
const mockClient = createMockClient({
post: vi.fn().mockResolvedValueOnce({
info: { id: "m2", role: "assistant" },
parts: [{ type: "text", text: "Sure" }],
}),
});
const tools = new Map<string, Function>();
const mockServer = {
tool: vi.fn((...args: unknown[]) => {
tools.set(args[0] as string, args[args.length - 1] as Function);
}),
} as unknown as McpServer;
registerWorkflowTools(mockServer, mockClient);
const handler = tools.get("opencode_reply")!;
await handler({
sessionId: "s1",
prompt: "follow up",
providerID: "openai",
modelID: "gpt-5.4",
variant: "low",
});
const [, body] = (mockClient.post as ReturnType<typeof vi.fn>).mock.calls[0];
expect(body.model).toEqual({ providerID: "openai", modelID: "gpt-5.4" });
expect(body.model).not.toHaveProperty("variant");
expect(body.variant).toBe("low");
});
});

describe("opencode_context", () => {
Expand Down Expand Up @@ -1156,6 +1209,35 @@ describe("Tool handlers", () => {
expect(result.content[0].text).not.toContain("WARNING");
});

it("sends variant as a top-level field", async () => {
const mockClient = createMockClient({
post: vi.fn().mockResolvedValueOnce({
info: { id: "m1", role: "assistant" },
parts: [{ type: "text", text: "Here is the answer" }],
}),
});
const tools = new Map<string, Function>();
const mockServer = {
tool: vi.fn((...args: unknown[]) => {
tools.set(args[0] as string, args[args.length - 1] as Function);
}),
} as unknown as McpServer;
registerMessageTools(mockServer, mockClient);

const handler = tools.get("opencode_message_send")!;
await handler({
sessionId: "s1",
text: "hello",
providerID: "openai",
modelID: "gpt-5.4",
variant: "xhigh",
});
const [, body] = (mockClient.post as ReturnType<typeof vi.fn>).mock.calls[0];
expect(body.model).toEqual({ providerID: "openai", modelID: "gpt-5.4" });
expect(body.model).not.toHaveProperty("variant");
expect(body.variant).toBe("xhigh");
});

it("returns 'Empty response.' when formatted output is empty string", async () => {
const mockClient = createMockClient({
post: vi.fn().mockResolvedValueOnce(null),
Expand Down