diff --git a/CHANGELOG.md b/CHANGELOG.md
index 668a91823..68ca94c1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,6 +48,14 @@ Status: unreleased.
 
 ## 2026.1.24-2
 
+## [Unreleased]
+
+### Added
+- DeepSeek provider support with `deepseek-chat` and `deepseek-reasoner` models
+  - Set `DEEPSEEK_API_KEY` environment variable to enable
+  - OpenAI-compatible API at https://api.deepseek.com/v1
+  - Supports 128K context window
+
 ### Fixes
 - Packaging: include dist/link-understanding output in npm tarball (fixes missing apply.js import on install).
 
diff --git a/src/agents/model-auth.ts b/src/agents/model-auth.ts
index 680d0f53c..e987ecf06 100644
--- a/src/agents/model-auth.ts
+++ b/src/agents/model-auth.ts
@@ -281,6 +281,7 @@ export function resolveEnvApiKey(provider: string): EnvApiKeyResult | null {
     moonshot: "MOONSHOT_API_KEY",
     "kimi-code": "KIMICODE_API_KEY",
     minimax: "MINIMAX_API_KEY",
+    deepseek: "DEEPSEEK_API_KEY",
     synthetic: "SYNTHETIC_API_KEY",
     venice: "VENICE_API_KEY",
     mistral: "MISTRAL_API_KEY",
diff --git a/src/agents/models-config.providers.ts b/src/agents/models-config.providers.ts
index 996f09dd0..88258ee78 100644
--- a/src/agents/models-config.providers.ts
+++ b/src/agents/models-config.providers.ts
@@ -64,6 +64,19 @@ const QWEN_PORTAL_DEFAULT_COST = {
   cacheWrite: 0,
 };
 
+const DEEPSEEK_BASE_URL = "https://api.deepseek.com/v1";
+const DEEPSEEK_CHAT_MODEL_ID = "deepseek-chat";
+const DEEPSEEK_REASONER_MODEL_ID = "deepseek-reasoner";
+const DEEPSEEK_CONTEXT_WINDOW = 128000;
+const DEEPSEEK_CHAT_MAX_TOKENS = 8192;
+const DEEPSEEK_REASONER_MAX_TOKENS = 64000;
+const DEEPSEEK_COST = {
+  input: 0.28,
+  output: 1.1,
+  cacheRead: 0.028,
+  cacheWrite: 0.28,
+};
+
 const OLLAMA_BASE_URL = "http://127.0.0.1:11434/v1";
 const OLLAMA_API_BASE_URL = "http://127.0.0.1:11434";
 const OLLAMA_DEFAULT_CONTEXT_WINDOW = 128000;
@@ -333,6 +346,33 @@ function buildQwenPortalProvider(): ProviderConfig {
   };
 }
 
+function buildDeepSeekProvider(): ProviderConfig {
+  return {
+    baseUrl: DEEPSEEK_BASE_URL,
+    api: "openai-completions",
+    models: [
+      {
+        id: DEEPSEEK_CHAT_MODEL_ID,
+        name: "DeepSeek V3.2 Chat",
+        reasoning: false,
+        input: ["text"],
+        cost: DEEPSEEK_COST,
+        contextWindow: DEEPSEEK_CONTEXT_WINDOW,
+        maxTokens: DEEPSEEK_CHAT_MAX_TOKENS,
+      },
+      {
+        id: DEEPSEEK_REASONER_MODEL_ID,
+        name: "DeepSeek V3.2 Reasoner",
+        reasoning: true,
+        input: ["text"],
+        cost: DEEPSEEK_COST,
+        contextWindow: DEEPSEEK_CONTEXT_WINDOW,
+        maxTokens: DEEPSEEK_REASONER_MAX_TOKENS,
+      },
+    ],
+  };
+}
+
 function buildSyntheticProvider(): ProviderConfig {
   return {
     baseUrl: SYNTHETIC_BASE_URL,
@@ -388,6 +428,13 @@ export async function resolveImplicitProviders(params: {
     providers["kimi-code"] = { ...buildKimiCodeProvider(), apiKey: kimiCodeKey };
   }
 
+  const deepseekKey =
+    resolveEnvApiKeyVarName("deepseek") ??
+    resolveApiKeyFromProfiles({ provider: "deepseek", store: authStore });
+  if (deepseekKey) {
+    providers.deepseek = { ...buildDeepSeekProvider(), apiKey: deepseekKey };
+  }
+
   const syntheticKey =
     resolveEnvApiKeyVarName("synthetic") ??
     resolveApiKeyFromProfiles({ provider: "synthetic", store: authStore });
diff --git a/src/agents/models-config.skips-writing-models-json-no-env-token.test.ts b/src/agents/models-config.skips-writing-models-json-no-env-token.test.ts
index 93b7ee628..8f084e40b 100644
--- a/src/agents/models-config.skips-writing-models-json-no-env-token.test.ts
+++ b/src/agents/models-config.skips-writing-models-json-no-env-token.test.ts
@@ -51,6 +51,7 @@ describe("models-config", () => {
       const previousKimiCode = process.env.KIMICODE_API_KEY;
       const previousMinimax = process.env.MINIMAX_API_KEY;
       const previousMoonshot = process.env.MOONSHOT_API_KEY;
+      const previousDeepSeek = process.env.DEEPSEEK_API_KEY;
       const previousSynthetic = process.env.SYNTHETIC_API_KEY;
       const previousVenice = process.env.VENICE_API_KEY;
       delete process.env.COPILOT_GITHUB_TOKEN;
@@ -59,6 +60,7 @@ describe("models-config", () => {
       delete process.env.KIMICODE_API_KEY;
       delete process.env.MINIMAX_API_KEY;
       delete process.env.MOONSHOT_API_KEY;
+      delete process.env.DEEPSEEK_API_KEY;
       delete process.env.SYNTHETIC_API_KEY;
       delete process.env.VENICE_API_KEY;
 
@@ -89,6 +91,8 @@ describe("models-config", () => {
         else process.env.MINIMAX_API_KEY = previousMinimax;
         if (previousMoonshot === undefined) delete process.env.MOONSHOT_API_KEY;
         else process.env.MOONSHOT_API_KEY = previousMoonshot;
+        if (previousDeepSeek === undefined) delete process.env.DEEPSEEK_API_KEY;
+        else process.env.DEEPSEEK_API_KEY = previousDeepSeek;
         if (previousSynthetic === undefined) delete process.env.SYNTHETIC_API_KEY;
         else process.env.SYNTHETIC_API_KEY = previousSynthetic;
         if (previousVenice === undefined) delete process.env.VENICE_API_KEY;
@@ -181,3 +185,38 @@ describe("models-config", () => {
     });
   });
 });
+
+it("adds deepseek provider when DEEPSEEK_API_KEY is set", async () => {
+  await withTempHome(async () => {
+    vi.resetModules();
+    const prevKey = process.env.DEEPSEEK_API_KEY;
+    process.env.DEEPSEEK_API_KEY = "sk-deepseek-test";
+    try {
+      const { ensureClawdbotModelsJson } = await import("./models-config.js");
+      const { resolveClawdbotAgentDir } = await import("./agent-paths.js");
+
+      await ensureClawdbotModelsJson({});
+
+      const modelPath = path.join(resolveClawdbotAgentDir(), "models.json");
+      const raw = await fs.readFile(modelPath, "utf8");
+      const parsed = JSON.parse(raw) as {
+        providers: Record<
+          string,
+          {
+            baseUrl?: string;
+            apiKey?: string;
+            models?: Array<{ id: string }>;
+          }
+        >;
+      };
+      expect(parsed.providers.deepseek?.baseUrl).toBe("https://api.deepseek.com/v1");
+      expect(parsed.providers.deepseek?.apiKey).toBe("DEEPSEEK_API_KEY");
+      const ids = parsed.providers.deepseek?.models?.map((model) => model.id);
+      expect(ids).toContain("deepseek-chat");
+      expect(ids).toContain("deepseek-reasoner");
+    } finally {
+      if (prevKey === undefined) delete process.env.DEEPSEEK_API_KEY;
+      else process.env.DEEPSEEK_API_KEY = prevKey;
+    }
+  });
+});
diff --git a/src/commands/auth-choice-options.ts b/src/commands/auth-choice-options.ts
index f13eef365..d8bb498da 100644
--- a/src/commands/auth-choice-options.ts
+++ b/src/commands/auth-choice-options.ts
@@ -20,6 +20,7 @@ export type AuthChoiceGroupId =
   | "zai"
   | "opencode-zen"
   | "minimax"
+  | "deepseek"
   | "synthetic"
   | "venice"
   | "qwen";
@@ -55,6 +56,12 @@ const AUTH_CHOICE_GROUP_DEFS: {
     hint: "M2.1 (recommended)",
     choices: ["minimax-api", "minimax-api-lightning"],
   },
+  {
+    value: "deepseek",
+    label: "DeepSeek",
+    hint: "V3.2 Chat + Reasoner",
+    choices: ["deepseek-api-key"],
+  },
   {
     value: "qwen",
     label: "Qwen",
diff --git a/src/commands/auth-choice.apply.api-providers.ts b/src/commands/auth-choice.apply.api-providers.ts
index 8be02008b..92b8e21ef 100644
--- a/src/commands/auth-choice.apply.api-providers.ts
+++ b/src/commands/auth-choice.apply.api-providers.ts
@@ -13,6 +13,8 @@ import {
 } from "./google-gemini-model-default.js";
 import {
   applyAuthProfileConfig,
+  applyDeepSeekConfig,
+  applyDeepSeekProviderConfig,
   applyKimiCodeConfig,
   applyKimiCodeProviderConfig,
   applyMoonshotConfig,
@@ -579,5 +581,64 @@ export async function applyAuthChoiceApiProviders(
     return { config: nextConfig, agentModelOverride };
   }
 
+  if (authChoice === "deepseek-api-key") {
+    let hasCredential = false;
+
+    if (!hasCredential && params.opts?.token && params.opts?.tokenProvider === "deepseek") {
+      await setDeepSeekApiKey(normalizeApiKeyInput(params.opts.token), params.agentDir);
+      hasCredential = true;
+    }
+
+    if (!hasCredential) {
+      await params.prompter.note(
+        [
+          "DeepSeek provides high-performance AI models with competitive pricing.",
+          "Get your API key at: https://platform.deepseek.com/",
+          "Supports both chat and reasoning models.",
+        ].join("\n"),
+        "DeepSeek",
+      );
+    }
+
+    const envKey = resolveEnvApiKey("deepseek");
+    if (envKey) {
+      const useExisting = await params.prompter.confirm({
+        message: `Use existing DEEPSEEK_API_KEY (${envKey.source}, ${formatApiKeyPreview(envKey.apiKey)})?`,
+        initialValue: true,
+      });
+      if (useExisting) {
+        await setDeepSeekApiKey(envKey.apiKey, params.agentDir);
+        hasCredential = true;
+      }
+    }
+    if (!hasCredential) {
+      const key = await params.prompter.text({
+        message: "Enter DeepSeek API key",
+        validate: validateApiKeyInput,
+      });
+      await setDeepSeekApiKey(normalizeApiKeyInput(String(key)), params.agentDir);
+    }
+    nextConfig = applyAuthProfileConfig(nextConfig, {
+      profileId: "deepseek:default",
+      provider: "deepseek",
+      mode: "api_key",
+    });
+    {
+      const applied = await applyDefaultModelChoice({
+        config: nextConfig,
+        setDefaultModel: params.setDefaultModel,
+        defaultModel: "deepseek/deepseek-chat",
+        applyDefaultConfig: applyDeepSeekConfig,
+        applyProviderConfig: applyDeepSeekProviderConfig,
+        noteDefault: "deepseek/deepseek-chat",
+        noteAgentModel,
+        prompter: params.prompter,
+      });
+      nextConfig = applied.config;
+      agentModelOverride = applied.agentModelOverride ?? agentModelOverride;
+    }
+    return { config: nextConfig, agentModelOverride };
+  }
+
   return null;
 }
diff --git a/src/commands/auth-choice.preferred-provider.ts b/src/commands/auth-choice.preferred-provider.ts
index 6fe26b59a..737328bca 100644
--- a/src/commands/auth-choice.preferred-provider.ts
+++ b/src/commands/auth-choice.preferred-provider.ts
@@ -20,6 +20,7 @@ const PREFERRED_PROVIDER_BY_AUTH_CHOICE: Partial<Record<AuthChoice, string>> = {
   "zai-api-key": "zai",
   "synthetic-api-key": "synthetic",
   "venice-api-key": "venice",
+  "deepseek-api-key": "deepseek",
   "github-copilot": "github-copilot",
   "copilot-proxy": "copilot-proxy",
   "minimax-cloud": "minimax",
diff --git a/src/commands/onboard-auth.config-core.ts b/src/commands/onboard-auth.config-core.ts
index 0d3a8523a..00ef68e39 100644
--- a/src/commands/onboard-auth.config-core.ts
+++ b/src/commands/onboard-auth.config-core.ts
@@ -411,6 +411,71 @@ export function applyVeniceConfig(cfg: ClawdbotConfig): ClawdbotConfig {
   };
 }
 
+const DEEPSEEK_BASE_URL = "https://api.deepseek.com/v1";
+const DEEPSEEK_DEFAULT_MODEL_REF = "deepseek/deepseek-chat";
+
+export function applyDeepSeekProviderConfig(cfg: ClawdbotConfig): ClawdbotConfig {
+  const providers = { ...cfg.models?.providers };
+  const existingProvider = providers.deepseek;
+  const existingModels = Array.isArray(existingProvider?.models) ? existingProvider.models : [];
+  const { apiKey: existingApiKey, ...existingProviderRest } = (existingProvider ?? {}) as Record<
+    string,
+    unknown
+  > as { apiKey?: string };
+  const resolvedApiKey = typeof existingApiKey === "string" ? existingApiKey : undefined;
+  const normalizedApiKey = resolvedApiKey?.trim();
+  providers.deepseek = {
+    ...existingProviderRest,
+    baseUrl: DEEPSEEK_BASE_URL,
+    api: "openai-completions",
+    ...(normalizedApiKey ? { apiKey: normalizedApiKey } : {}),
+    models: existingModels,
+  };
+
+  const models = { ...cfg.agents?.defaults?.models };
+  models[DEEPSEEK_DEFAULT_MODEL_REF] = {
+    ...models[DEEPSEEK_DEFAULT_MODEL_REF],
+    alias: "DeepSeek",
+  };
+
+  return {
+    ...cfg,
+    agents: {
+      ...cfg.agents,
+      defaults: {
+        ...cfg.agents?.defaults,
+        models,
+      },
+    },
+    models: {
+      mode: cfg.models?.mode ?? "merge",
+      providers,
+    },
+  };
+}
+
+export function applyDeepSeekConfig(cfg: ClawdbotConfig): ClawdbotConfig {
+  const next = applyDeepSeekProviderConfig(cfg);
+  const existingModel = next.agents?.defaults?.model;
+  return {
+    ...next,
+    agents: {
+      ...next.agents,
+      defaults: {
+        ...next.agents?.defaults,
+        model: {
+          ...(existingModel && "fallbacks" in (existingModel as Record<string, unknown>)
+            ? {
+                fallbacks: (existingModel as { fallbacks?: string[] }).fallbacks,
+              }
+            : undefined),
+          primary: DEEPSEEK_DEFAULT_MODEL_REF,
+        },
+      },
+    },
+  };
+}
+
 export function applyAuthProfileConfig(
   cfg: ClawdbotConfig,
   params: {
diff --git a/src/commands/onboard-auth.credentials.ts b/src/commands/onboard-auth.credentials.ts
index 0c7dff409..4deaca324 100644
--- a/src/commands/onboard-auth.credentials.ts
+++ b/src/commands/onboard-auth.credentials.ts
@@ -60,6 +60,19 @@ export async function setMinimaxApiKey(key: string, agentDir?: string) {
   });
 }
 
+export async function setDeepSeekApiKey(key: string, agentDir?: string) {
+  // Write to resolved agent dir so gateway finds credentials on startup.
+  upsertAuthProfile({
+    profileId: "deepseek:default",
+    credential: {
+      type: "api_key",
+      provider: "deepseek",
+      key,
+    },
+    agentDir: resolveAuthAgentDir(agentDir),
+  });
+}
+
 export async function setMoonshotApiKey(key: string, agentDir?: string) {
   // Write to resolved agent dir so gateway finds credentials on startup.
   upsertAuthProfile({
diff --git a/src/commands/onboard-auth.ts b/src/commands/onboard-auth.ts
index b122d89cf..abcdbbd72 100644
--- a/src/commands/onboard-auth.ts
+++ b/src/commands/onboard-auth.ts
@@ -5,6 +5,8 @@ export {
 export { VENICE_DEFAULT_MODEL_ID, VENICE_DEFAULT_MODEL_REF } from "../agents/venice-models.js";
 export {
   applyAuthProfileConfig,
+  applyDeepSeekConfig,
+  applyDeepSeekProviderConfig,
   applyKimiCodeConfig,
   applyKimiCodeProviderConfig,
   applyMoonshotConfig,
@@ -35,6 +37,7 @@ export {
 export {
   OPENROUTER_DEFAULT_MODEL_REF,
   setAnthropicApiKey,
+  setDeepSeekApiKey,
   setGeminiApiKey,
   setKimiCodeApiKey,
   setMinimaxApiKey,
diff --git a/src/commands/onboard-types.ts b/src/commands/onboard-types.ts
index 84c15afc4..9844a488c 100644
--- a/src/commands/onboard-types.ts
+++ b/src/commands/onboard-types.ts
@@ -27,6 +27,7 @@ export type AuthChoice =
   | "minimax"
   | "minimax-api"
   | "minimax-api-lightning"
+  | "deepseek-api-key"
   | "opencode-zen"
   | "github-copilot"
   | "copilot-proxy"
@@ -68,6 +69,7 @@ export type OnboardOptions = {
   geminiApiKey?: string;
   zaiApiKey?: string;
   minimaxApiKey?: string;
+  deepseekApiKey?: string;
   syntheticApiKey?: string;
   veniceApiKey?: string;
   opencodeZenApiKey?: string;