diff --git a/agents/langchain-deepagents-code/generate-config.ts b/agents/langchain-deepagents-code/generate-config.ts
index 836134bf2f..b0c3a55be1 100644
--- a/agents/langchain-deepagents-code/generate-config.ts
+++ b/agents/langchain-deepagents-code/generate-config.ts
@@ -8,9 +8,10 @@
 
 import { chmodSync, mkdirSync, writeFileSync } from "node:fs";
 import { homedir } from "node:os";
-import { join } from "node:path";
+import { join, resolve } from "node:path";
+import { pathToFileURL } from "node:url";
 
-type Settings = {
+export type Settings = {
   model: string;
   baseUrl: string;
   providerKey: string;
@@ -86,16 +87,40 @@ function tomlArray(values: readonly string[]): string {
   return `[${values.map(tomlString).join(", ")}]`;
 }
 
-function modelNameForOpenAiProvider(model: string): string {
+/**
+ * Return the model identifier NemoClaw should write into the deepagents
+ * config.toml as the value NemoClaw prepends `openai:` to.
+ *
+ * Two contradictory shapes reach `NEMOCLAW_MODEL` at build time:
+ *   1. A bare model id — this is what NemoClaw sets non-interactively via
+ *      `src/lib/onboard/providers.ts::getNonInteractiveModel`. The bare id
+ *      may legally contain `:` — the `NEMOCLAW_MODEL` build-arg validator's
+ *      regex explicitly allows `:`, precisely because Ollama tags carry a
+ *      `<name>:<tag>` separator (e.g. `qwen2.5:7b`, `llama3.1:8b-instruct-q4_0`).
+ *   2. An `openai:<model>` provider-qualified id — some callers pre-prefix
+ *      the identifier with the deepagents provider label; without a strip
+ *      the emitted default would become `openai:openai:<model>` (a double
+ *      prefix that the deepagents CLI rejects). See the existing regression
+ *      test `test/langchain-deepagents-code-config.test.ts::does not
+ *      double-prefix provider-qualified model names`.
+ *
+ * The previous implementation split on the FIRST `:` and returned the
+ * suffix, which handled (2) but silently ate the leading segment of any
+ * (1) that carried a colon — producing `openai:7b` in place of
+ * `openai:qwen2.5:7b` (#6325).
+ *
+ * Strip ONLY the exact `openai:` provider label — the sole provider we
+ * emit under `[models.providers.openai]`. Any other colon in the model id
+ * is part of the model tag itself (Ollama's `name:tag` separator, HF-style
+ * `org/name:tag` variant qualifiers, etc.) and MUST pass through.
+ */
+export function modelNameForOpenAiProvider(model: string): string {
   const trimmed = model.trim();
-  const providerSeparator = trimmed.indexOf(":");
-  if (providerSeparator > 0) {
-    return trimmed.slice(providerSeparator + 1);
-  }
-  return trimmed;
+  const PROVIDER_PREFIX = "openai:";
+  return trimmed.startsWith(PROVIDER_PREFIX) ? trimmed.slice(PROVIDER_PREFIX.length) : trimmed;
 }
 
-function buildConfig(settings: Settings): string {
+export function buildConfig(settings: Settings): string {
   const model = modelNameForOpenAiProvider(settings.model);
   const defaultModel = `openai:${model}`;
   return [
@@ -123,7 +148,7 @@ function buildConfig(settings: Settings): string {
   ].join("\n");
 }
 
-function main(): void {
+export function main(): void {
   const settings = readSettings(process.env);
   const configDir = join(homedir(), ".deepagents");
   mkdirSync(join(configDir, ".state"), { recursive: true, mode: 0o770 });
@@ -138,4 +163,8 @@ function main(): void {
   );
 }
 
-main();
+function isMainModule(): boolean {
+  return process.argv[1] ? import.meta.url === pathToFileURL(resolve(process.argv[1])).href : false;
+}
+
+if (isMainModule()) main();
diff --git a/test/generate-dcode-config.test.ts b/test/generate-dcode-config.test.ts
new file mode 100644
index 0000000000..bc5a72d2c8
--- /dev/null
+++ b/test/generate-dcode-config.test.ts
@@ -0,0 +1,92 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import { describe, expect, it } from "vitest";
+import {
+  buildConfig,
+  modelNameForOpenAiProvider,
+  type Settings,
+} from "../agents/langchain-deepagents-code/generate-config.ts";
+
+const BASE_SETTINGS: Settings = {
+  model: "nvidia/nemotron-3-super-120b-a12b",
+  baseUrl: "https://inference.local/v1",
+  providerKey: "inference",
+  upstreamProvider: "nvidia-prod",
+  inferenceApi: "openai-completions",
+};
+
+describe("modelNameForOpenAiProvider (#6325)", () => {
+  it("preserves an Ollama tag containing a colon (`qwen2.5:7b`) verbatim", () => {
+    // Regression for #6325: the old implementation split on the first `:`
+    // and returned only the suffix, dropping `qwen2.5` and producing `7b`.
+    expect(modelNameForOpenAiProvider("qwen2.5:7b")).toBe("qwen2.5:7b");
+  });
+
+  it("preserves an Ollama tag with an additional dash-qualified variant (`llama3.1:8b-instruct-q4_0`)", () => {
+    expect(modelNameForOpenAiProvider("llama3.1:8b-instruct-q4_0")).toBe(
+      "llama3.1:8b-instruct-q4_0",
+    );
+  });
+
+  it("passes non-colonized model ids through unchanged", () => {
+    expect(modelNameForOpenAiProvider("nvidia/nemotron-3-super-120b-a12b")).toBe(
+      "nvidia/nemotron-3-super-120b-a12b",
+    );
+    expect(modelNameForOpenAiProvider("gpt-5.4-mini")).toBe("gpt-5.4-mini");
+  });
+
+  it("trims surrounding whitespace but does not otherwise mutate the value", () => {
+    expect(modelNameForOpenAiProvider("  qwen2.5:7b  ")).toBe("qwen2.5:7b");
+  });
+
+  it("strips an already-`openai:`-qualified provider label (existing regression)", () => {
+    // Pre-existing contract: some callers pre-prefix the model id with the
+    // deepagents provider label. Without a strip the emitted default would
+    // become `openai:openai:gpt-oss-120b`, which the deepagents CLI rejects.
+    expect(modelNameForOpenAiProvider("openai:gpt-oss-120b")).toBe("gpt-oss-120b");
+  });
+
+  it("only strips the exact `openai:` prefix — a colonized model that starts with a different label is unchanged", () => {
+    // Guard against a hypothetical future regression where a naive
+    // `indexOf(":")` re-appears: `qwen2.5:7b` starts with `qwen2.5`, not
+    // `openai`, so nothing may be stripped.
+    expect(modelNameForOpenAiProvider("qwen2.5:7b")).toBe("qwen2.5:7b");
+    // Ditto for other legitimate colon-carrying ids.
+    expect(modelNameForOpenAiProvider("anthropic:claude-3-sonnet")).toBe(
+      "anthropic:claude-3-sonnet",
+    );
+  });
+});
+
+describe("buildConfig for deepagents (#6325)", () => {
+  it("emits the full Ollama colon-tagged model in both the default and the openai models array", () => {
+    // Reporter's exact scenario: an Ollama model `qwen2.5:7b`. The generated
+    // config.toml must keep the full tag on both the `default = "openai:…"`
+    // line and inside `[models.providers.openai].models = […]`.
+    const toml = buildConfig({ ...BASE_SETTINGS, model: "qwen2.5:7b" });
+    expect(toml).toContain(`default = "openai:qwen2.5:7b"`);
+    expect(toml).toContain(`models = ["qwen2.5:7b"]`);
+    expect(toml).not.toContain(`default = "openai:7b"`);
+    expect(toml).not.toContain(`models = ["7b"]`);
+  });
+
+  it("emits an unambiguous default + models entry when the model has no colon", () => {
+    const toml = buildConfig({
+      ...BASE_SETTINGS,
+      model: "nvidia/nemotron-3-super-120b-a12b",
+    });
+    expect(toml).toContain(`default = "openai:nvidia/nemotron-3-super-120b-a12b"`);
+    expect(toml).toContain(`models = ["nvidia/nemotron-3-super-120b-a12b"]`);
+  });
+
+  it("keeps the openai: provider prefix as the only leading `openai:` token", () => {
+    // Sanity: the fix must not accidentally double-prefix (e.g. produce
+    // `openai:openai:qwen2.5:7b`).
+    const toml = buildConfig({ ...BASE_SETTINGS, model: "qwen2.5:7b" });
+    const openaiPrefixes = toml.match(/"openai:/g) ?? [];
+    // One occurrence in the `[models] default` line, one in the `[models.providers.openai]`
+    // header is a bare `openai` (no `"openai:` prefix), so the default-line hit is unique.
+    expect(openaiPrefixes).toHaveLength(1);
+  });
+});