feat: support apply_patch for DeepSeek models

AGENTS.md

@@ -21,7 +21,7 @@ Conventions for human contributors and AI agents working on this repository.
 ## Constraints
 
 - No Bun APIs. Runtime is Node only.
-- This extension registers the `apply_patch` tool and only activates it for OpenAI GPT-family models.
+- This extension registers the `apply_patch` tool and only activates it for OpenAI GPT-family models and DeepSeek models (id prefix `deepseek-`) exposed through `openai-responses` / `openai-codex-responses` APIs.
 - Keep the tool schema, grammar, and descriptions byte-for-byte compatible with Codex unless intentionally updating the golden source.
 - No dependency on pi-coding-agent internal modules outside the documented public extension API in `@mariozechner/pi-coding-agent`.
 

CHANGELOG.md

@@ -6,3 +6,4 @@
 
 - Initial standalone `apply_patch` pi extension.
 - Support GPT models exposed through custom `openai-responses` and `openai-codex-responses` providers.
+- Support DeepSeek models (`deepseek-` id prefix, e.g. `deepseek-v4-flash` via OpenCode Go Responses) exposed through `openai-responses` and `openai-codex-responses` providers.

README.md

@@ -10,7 +10,8 @@ The extension registers one LLM-callable tool: `apply_patch`. The tool accepts C
 |------|--------|
 | OpenAI GPT provider active | replaces `write` and `edit` with `apply_patch` |
 | Custom `openai-responses` GPT provider active | replaces `write` and `edit` with `apply_patch` |
-| Non-GPT model active | restores the original `write` and `edit` toolset |
+| DeepSeek model on `openai-responses` provider (e.g. `deepseek-v4-flash` via OpenCode Go Responses) | replaces `write` and `edit` with `apply_patch` |
+| Non-GPT / non-DeepSeek model active | restores the original `write` and `edit` toolset |
 | Raw freeform patch input | accepted and applied |
 | JSON `{ "input": "..." }` patch input | accepted and applied |
 | Absolute or parent-escaping path | accepted and resolved by Node path semantics |
@@ -35,7 +36,7 @@ Use this tool to edit files with the Codex patch format.
 
 Pi exposes this as a freeform grammar tool. Models with `compat.supportsOpenAIGrammarTools` enabled receive an OpenAI custom grammar tool; other Responses-compatible models fall back to a function tool with an `input` string.
 
-Custom provider names are supported when the model id starts with `gpt-` and its Pi API is `openai-responses` or `openai-codex-responses`. For example, a model registered as `my-proxy/gpt-5` with `api: "openai-responses"` activates `apply_patch` without adding the provider name to a hard-coded allowlist.
+Custom provider names are supported when the model id starts with `gpt-` or `deepseek-` and its Pi API is `openai-responses` or `openai-codex-responses`. For example, a model registered as `my-proxy/gpt-5` or `opencode-go-responses/deepseek-v4-flash` with `api: "openai-responses"` activates `apply_patch` without adding the provider name to a hard-coded allowlist.
 
 ## Installation
 

src/index.ts

@@ -178,6 +178,7 @@ function hasErrorCode(error: unknown, code: string): boolean {
 	return Boolean(error && typeof error === "object" && "code" in error && error.code === code);
 }
 
+const APPLY_PATCH_MODEL_ID_PREFIXES = ["gpt-", "deepseek-"] as const;
 const GPT_APPLY_PATCH_PROVIDERS = new Set(["openai", "openai-codex", "azure-openai-responses", "github-copilot"]);
 const GPT_APPLY_PATCH_APIS = new Set(["openai-responses", "openai-codex-responses"]);
 export const PATCH_PREVIEW_MAX_LINES = 16;
@@ -338,10 +339,10 @@ eof_line: "*** End of File" LF
 %import common.LF
 `;
 
-export function isOpenAIGptModel(
-	model: (Pick<Model<string>, "provider" | "id"> & Partial<Pick<Model<string>, "api">>) | undefined,
-): boolean {
-	if (!model?.id.startsWith("gpt-")) {
+export type ApplyPatchCandidateModel = Pick<Model<string>, "provider" | "id"> & Partial<Pick<Model<string>, "api">>;
+
+export function isApplyPatchCapableModel(model: ApplyPatchCandidateModel | undefined): boolean {
+	if (!model || !APPLY_PATCH_MODEL_ID_PREFIXES.some((prefix) => model.id.startsWith(prefix))) {
 		return false;
 	}
 
@@ -350,6 +351,11 @@ export function isOpenAIGptModel(
 	);
 }
 
+/** @deprecated Use {@link isApplyPatchCapableModel}. */
+export function isOpenAIGptModel(model: ApplyPatchCandidateModel | undefined): boolean {
+	return isApplyPatchCapableModel(model);
+}
+
 function normalizePatchText(patchText: string): string {
 	return patchText.replace(/\r\n/g, "\n").replace(/\r/g, "\n");
 }
@@ -1377,7 +1383,7 @@ function syncToolset(
 	model: Model<string> | undefined,
 ): void {
 	const currentToolNames = pi.getActiveTools();
-	if (isOpenAIGptModel(model)) {
+	if (isApplyPatchCapableModel(model)) {
 		pi.setActiveTools(replaceEditToolsWithApplyPatch(currentToolNames));
 		return;
 	}

test/index.test.ts

@@ -10,6 +10,7 @@ import {
 	createApplyPatchTool,
 	extractPatchedPaths,
 	type FreeformToolFormat,
+	isApplyPatchCapableModel,
 	isOpenAIGptModel,
 	PatchParseError,
 	registerApplyPatchExtension,
@@ -173,6 +174,22 @@ describe("pi-apply-patch", () => {
 		expect(harness.getActiveTools()).toEqual(["read", "apply_patch"]);
 	});
 
+	it("#given DeepSeek model on custom Responses provider #when session starts #then enables apply_patch", async () => {
+		// given
+		const harness = createToolsetTestApi(["read", "edit", "write"]);
+		registerApplyPatchExtension(harness.api);
+
+		// when
+		await harness.trigger("session_start", {
+			provider: "opencode-go-responses",
+			id: "deepseek-v4-flash",
+			api: "openai-responses",
+		});
+
+		// then
+		expect(harness.getActiveTools()).toEqual(["read", "apply_patch"]);
+	});
+
 	it("#given non GPT model and no original edit tools #when session starts #then restores standard edit tools", async () => {
 		// given
 		const harness = createToolsetTestApi(["read", "apply_patch"]);
@@ -1097,14 +1114,39 @@ EOF`;
 		expect(extractPatchedPaths(patch)).toEqual(["src/app.ts", "src/new.ts", "src/old.ts", "src/moved.ts"]);
 	});
 
-	it("#given model metadata #when checking GPT activation #then matches known providers and Responses APIs", () => {
+	it("#given model metadata #when checking apply_patch activation #then matches GPT and DeepSeek models on Responses APIs", () => {
+		expect(isApplyPatchCapableModel({ provider: "openai", id: "gpt-5" })).toBe(true);
+		expect(isApplyPatchCapableModel({ provider: "openai-codex", id: "gpt-5.5" })).toBe(true);
+		expect(isApplyPatchCapableModel({ provider: "my-proxy", id: "gpt-5", api: "openai-responses" })).toBe(true);
+		expect(isApplyPatchCapableModel({ provider: "codex-proxy", id: "gpt-5", api: "openai-codex-responses" })).toBe(
+			true,
+		);
+		expect(
+			isApplyPatchCapableModel({
+				provider: "opencode-go-responses",
+				id: "deepseek-v4-flash",
+				api: "openai-responses",
+			}),
+		).toBe(true);
+		expect(
+			isApplyPatchCapableModel({ provider: "my-proxy", id: "deepseek-v4-flash", api: "openai-codex-responses" }),
+		).toBe(true);
+		expect(isApplyPatchCapableModel({ provider: "openai", id: "o1" })).toBe(false);
+		expect(isApplyPatchCapableModel({ provider: "anthropic", id: "gpt-5" })).toBe(false);
+		expect(isApplyPatchCapableModel({ provider: "my-proxy", id: "claude-sonnet", api: "openai-responses" })).toBe(
+			false,
+		);
+		expect(isApplyPatchCapableModel({ provider: "anthropic-proxy", id: "gpt-5", api: "anthropic-messages" })).toBe(
+			false,
+		);
+		expect(isApplyPatchCapableModel({ provider: "my-proxy", id: "deepseek-chat", api: "anthropic-messages" })).toBe(
+			false,
+		);
+
+		// legacy alias stays consistent
+		expect(
+			isOpenAIGptModel({ provider: "opencode-go-responses", id: "deepseek-v4-flash", api: "openai-responses" }),
+		).toBe(true);
 		expect(isOpenAIGptModel({ provider: "openai", id: "gpt-5" })).toBe(true);
-		expect(isOpenAIGptModel({ provider: "openai-codex", id: "gpt-5.5" })).toBe(true);
-		expect(isOpenAIGptModel({ provider: "my-proxy", id: "gpt-5", api: "openai-responses" })).toBe(true);
-		expect(isOpenAIGptModel({ provider: "codex-proxy", id: "gpt-5", api: "openai-codex-responses" })).toBe(true);
-		expect(isOpenAIGptModel({ provider: "openai", id: "o1" })).toBe(false);
-		expect(isOpenAIGptModel({ provider: "anthropic", id: "gpt-5" })).toBe(false);
-		expect(isOpenAIGptModel({ provider: "my-proxy", id: "claude-sonnet", api: "openai-responses" })).toBe(false);
-		expect(isOpenAIGptModel({ provider: "anthropic-proxy", id: "gpt-5", api: "anthropic-messages" })).toBe(false);
 	});
 });