diff --git a/tests/test-pure-functions.ts b/tests/test-pure-functions.ts
new file mode 100644
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--- /dev/null
+++ b/tests/test-pure-functions.ts
@@ -0,0 +1,637 @@
+/**
+ * Unit tests for pi-commandcode-provider pure functions.
+ *
+ * These tests DON'T require pi's runtime or any network access.
+ * They verify message/tool/schema conversion logic in isolation.
+ *
+ * Run with: npx tsx tests/test-pure-functions.ts
+ * Or:      node --import tsx tests/test-pure-functions.ts
+ */
+
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+
+// ---------------------------------------------------------------------------
+// Pure functions copied from index.ts (standalone, no pi imports needed)
+// ---------------------------------------------------------------------------
+
+function uuid(): string {
+  return crypto.randomUUID();
+}
+
+function textContent(m: { content: any[] }): string {
+  return (m.content ?? [])
+    .filter((c: any) => c.type === "text")
+    .map((c: any) => c.text ?? "")
+    .join("\n");
+}
+
+function getEnvironmentInfo(): string {
+  return `${process.platform}-${process.arch}, Node.js ${process.version}`;
+}
+
+/**
+ * Minimal typebox → JSON Schema converter.
+ * Handles Object, String, Number, Boolean, Array, Union, Optional, Enum.
+ */
+function toJsonSchema(schema: any): any {
+  if (!schema) return {};
+  const s = schema as Record<string, any>;
+  const kind = s.kind ?? s.type;
+
+  if (s.enum) {
+    return { type: typeof s.enum[0], enum: s.enum };
+  }
+
+  switch (kind) {
+    case "string":
+    case "String":
+      return { type: "string" };
+    case "number":
+    case "Number":
+      return { type: "number" };
+    case "boolean":
+    case "Boolean":
+      return { type: "boolean" };
+    case "object":
+    case "Object": {
+      const props: Record<string, any> = {};
+      const inferredRequired: string[] = [];
+      if (s.properties) {
+        for (const [k, v] of Object.entries(s.properties)) {
+          props[k] = toJsonSchema(v);
+          if (!(v as any).optional && !s.optional?.includes?.(k))
+            inferredRequired.push(k);
+        }
+      }
+      const required = Array.isArray(s.required) ? s.required : inferredRequired;
+      const out: any = { type: "object" };
+      if (Object.keys(props).length) out.properties = props;
+      if (required.length) out.required = required;
+      return out;
+    }
+    case "array":
+    case "Array":
+      return { type: "array", items: toJsonSchema(s.items ?? s.element) };
+    case "union":
+    case "Union": {
+      const variants = s.variants ?? s.anyOf ?? [];
+      for (const v of variants) {
+        const schema = toJsonSchema(v);
+        if (schema && Object.keys(schema).length) return schema;
+      }
+      return {};
+    }
+    case "optional":
+    case "Optional":
+      return toJsonSchema(s.wrapped ?? s.inner);
+    default:
+      return {};
+  }
+}
+
+function toolsToJson(tools: any[]): any[] {
+  if (!tools) return [];
+  return tools.map((t) => {
+    const schema = t.parameters ? toJsonSchema(t.parameters) : {};
+    return {
+      type: "function",
+      name: t.name,
+      description: t.description,
+      input_schema: schema,
+    };
+  });
+}
+
+function messagesToCC(msgs: any[]): any[] {
+  const out: any[] = [];
+  for (const m of msgs) {
+    if (m.role === "user") {
+      out.push({
+        role: "user",
+        content: typeof m.content === "string" ? m.content : m.content,
+      });
+    } else if (m.role === "assistant") {
+      const parts: any[] = [];
+      for (const c of m.content) {
+        if (c.type === "text") {
+          parts.push({ type: "text", text: c.text });
+        } else if (c.type === "thinking") {
+          parts.push({ type: "reasoning", text: c.thinking });
+        } else if (c.type === "toolCall") {
+          parts.push({
+            type: "tool-call",
+            toolCallId: c.id,
+            toolName: c.name,
+            input: c.arguments,
+          });
+        }
+      }
+      out.push({ role: "assistant", content: parts });
+    } else if (m.role === "toolResult") {
+      out.push({
+        role: "tool",
+        content: [
+          {
+            type: "tool-result",
+            toolCallId: m.toolCallId,
+            toolName: m.toolName,
+            output: m.isError
+              ? { type: "error-text", value: textContent(m) }
+              : { type: "text", value: textContent(m) },
+          },
+        ],
+      });
+    }
+  }
+  return out;
+}
+
+// ===========================================================================
+// Tests
+// ===========================================================================
+
+describe("uuid()", () => {
+  it("returns a valid UUID string", () => {
+    const id = uuid();
+    assert.match(id, /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i);
+  });
+
+  it("returns unique values on each call", () => {
+    const a = uuid();
+    const b = uuid();
+    assert.notEqual(a, b);
+  });
+});
+
+// ---------------------------------------------------------------
+// textContent
+// ---------------------------------------------------------------
+
+describe("textContent()", () => {
+  it("extracts text from content array", () => {
+    const msg = { content: [{ type: "text", text: "hello" }, { type: "text", text: "world" }] };
+    assert.equal(textContent(msg), "hello\nworld");
+  });
+
+  it("filters non-text content", () => {
+    const msg = { content: [{ type: "text", text: "hello" }, { type: "image", data: "x" }] };
+    assert.equal(textContent(msg), "hello");
+  });
+
+  it("returns empty string for empty content", () => {
+    assert.equal(textContent({ content: [] }), "");
+  });
+
+  it("handles missing content gracefully", () => {
+    assert.equal(textContent({ content: undefined as any }) ?? "", "");
+  });
+});
+
+// ---------------------------------------------------------------
+// getEnvironmentInfo
+// ---------------------------------------------------------------
+
+describe("getEnvironmentInfo()", () => {
+  it("returns string with platform, arch, and node version", () => {
+    const info = getEnvironmentInfo();
+    assert.match(info, /^(darwin|linux|win32)-/);
+    assert.ok(info.includes("Node.js"), `expected Node.js in: ${info}`);
+  });
+});
+
+// ---------------------------------------------------------------
+// toJsonSchema
+// ---------------------------------------------------------------
+
+describe("toJsonSchema — scalar types", () => {
+  it("handles string (lowercase kind)", () => {
+    assert.deepEqual(toJsonSchema({ kind: "string" }), { type: "string" });
+  });
+  it("handles String (capitalized)", () => {
+    assert.deepEqual(toJsonSchema({ kind: "String" }), { type: "string" });
+  });
+  it("handles number", () => {
+    assert.deepEqual(toJsonSchema({ kind: "number" }), { type: "number" });
+  });
+  it("handles Number", () => {
+    assert.deepEqual(toJsonSchema({ kind: "Number" }), { type: "number" });
+  });
+  it("handles boolean", () => {
+    assert.deepEqual(toJsonSchema({ kind: "boolean" }), { type: "boolean" });
+  });
+  it("handles Boolean", () => {
+    assert.deepEqual(toJsonSchema({ kind: "Boolean" }), { type: "boolean" });
+  });
+});
+
+describe("toJsonSchema — enum", () => {
+  it("detects enum by property (string values)", () => {
+    const schema = { kind: "string", enum: ["left", "right"] };
+    assert.deepEqual(toJsonSchema(schema), { type: "string", enum: ["left", "right"] });
+  });
+  it("detects enum by property (number values)", () => {
+    const schema = { kind: "number", enum: [1, 2, 3] };
+    assert.deepEqual(toJsonSchema(schema), { type: "number", enum: [1, 2, 3] });
+  });
+});
+
+describe("toJsonSchema — object", () => {
+  it("converts simple object with string props", () => {
+    const schema = {
+      kind: "object",
+      properties: {
+        name: { kind: "string" },
+        age: { kind: "number" },
+      },
+    };
+    assert.deepEqual(toJsonSchema(schema), {
+      type: "object",
+      properties: { name: { type: "string" }, age: { type: "number" } },
+      required: ["name", "age"],
+    });
+  });
+
+  it("marks optional properties correctly", () => {
+    const schema = {
+      kind: "object",
+      properties: {
+        name: { kind: "string" },
+        nickname: { kind: "string", optional: true },
+      },
+    };
+    const result = toJsonSchema(schema);
+    assert.deepEqual(result.required, ["name"]);
+    assert.deepEqual(result.properties?.nickname, { type: "string" });
+  });
+
+  it("handles optional via top-level optional array", () => {
+    const schema = {
+      kind: "Object",
+      properties: {
+        name: { kind: "string" },
+        age: { kind: "number" },
+      },
+      optional: ["age"],
+    };
+    const result = toJsonSchema(schema);
+    assert.deepEqual(result.required, ["name"]);
+  });
+
+  it("preserves TypeBox required arrays", () => {
+    const schema = {
+      type: "object",
+      properties: {
+        name: { type: "string" },
+        nickname: { type: "string" },
+      },
+      required: ["name"],
+    };
+    const result = toJsonSchema(schema);
+    assert.deepEqual(result.required, ["name"]);
+  });
+
+  it("handles empty object", () => {
+    assert.deepEqual(toJsonSchema({ kind: "object" }), { type: "object" });
+  });
+
+  it("handles Object (capitalized)", () => {
+    assert.deepEqual(toJsonSchema({ kind: "Object" }), { type: "object" });
+  });
+});
+
+describe("toJsonSchema — array", () => {
+  it("converts array with items", () => {
+    const schema = { kind: "array", items: { kind: "string" } };
+    assert.deepEqual(toJsonSchema(schema), { type: "array", items: { type: "string" } });
+  });
+
+  it("converts array with element (alternative prop name)", () => {
+    const schema = { kind: "Array", element: { kind: "number" } };
+    assert.deepEqual(toJsonSchema(schema), { type: "array", items: { type: "number" } });
+  });
+});
+
+describe("toJsonSchema — union", () => {
+  it("uses first non-empty variant", () => {
+    const schema = { kind: "union", variants: [{}, { kind: "string" }] };
+    assert.deepEqual(toJsonSchema(schema), { type: "string" });
+  });
+
+  it("uses anyOf as fallback property name", () => {
+    const schema = { kind: "Union", anyOf: [{ kind: "number" }] };
+    assert.deepEqual(toJsonSchema(schema), { type: "number" });
+  });
+
+  it("returns empty object for empty union", () => {
+    assert.deepEqual(toJsonSchema({ kind: "union", variants: [] }), {});
+  });
+});
+
+describe("toJsonSchema — optional", () => {
+  it("unwraps optional via wrapped", () => {
+    const schema = { kind: "optional", wrapped: { kind: "string" } };
+    assert.deepEqual(toJsonSchema(schema), { type: "string" });
+  });
+
+  it("unwraps optional via inner", () => {
+    const schema = { kind: "Optional", inner: { kind: "number" } };
+    assert.deepEqual(toJsonSchema(schema), { type: "number" });
+  });
+});
+
+describe("toJsonSchema — edge cases", () => {
+  it("returns empty object for null", () => {
+    assert.deepEqual(toJsonSchema(null), {});
+  });
+
+  it("returns empty object for undefined", () => {
+    assert.deepEqual(toJsonSchema(undefined), {});
+  });
+
+  it("handles unknown kind gracefully", () => {
+    assert.deepEqual(toJsonSchema({ kind: "foobar" }), {});
+  });
+
+  it("handles nested objects recursively", () => {
+    const schema = {
+      kind: "object",
+      properties: {
+        user: {
+          kind: "object",
+          properties: {
+            name: { kind: "string" },
+            address: {
+              kind: "object",
+              properties: { city: { kind: "string" } },
+            },
+          },
+        },
+      },
+    };
+    const result = toJsonSchema(schema);
+    assert.equal(result.properties.user.type, "object");
+    assert.equal(result.properties.user.properties.address.type, "object");
+    assert.equal(
+      result.properties.user.properties.address.properties.city.type,
+      "string",
+    );
+  });
+
+  it("handles type property as fallback for kind", () => {
+    assert.deepEqual(toJsonSchema({ type: "string" }), { type: "string" });
+  });
+});
+
+// ---------------------------------------------------------------
+// toolsToJson
+// ---------------------------------------------------------------
+
+describe("toolsToJson()", () => {
+  it("returns empty array for undefined", () => {
+    assert.deepEqual(toolsToJson(undefined as any), []);
+  });
+
+  it("returns empty array for null", () => {
+    assert.deepEqual(toolsToJson(null as any), []);
+  });
+
+  it("returns empty array for empty array", () => {
+    assert.deepEqual(toolsToJson([]), []);
+  });
+
+  it("converts a tool with object parameters", () => {
+    const tools = [
+      {
+        name: "get_weather",
+        description: "Get the weather for a city",
+        parameters: {
+          kind: "object",
+          properties: {
+            city: { kind: "string" },
+          },
+        },
+      },
+    ];
+    const result = toolsToJson(tools);
+    assert.equal(result.length, 1);
+    assert.equal(result[0].type, "function");
+    assert.equal(result[0].name, "get_weather");
+    assert.equal(result[0].description, "Get the weather for a city");
+    assert.deepEqual(result[0].input_schema, {
+      type: "object",
+      properties: { city: { type: "string" } },
+      required: ["city"],
+    });
+  });
+
+  it("handles tool without parameters", () => {
+    const tools = [{ name: "ping", description: "Check connectivity" }];
+    const result = toolsToJson(tools);
+    assert.equal(result.length, 1);
+    assert.deepEqual(result[0].input_schema, {});
+  });
+
+  it("converts multiple tools", () => {
+    const tools = [
+      { name: "tool_a", description: "A", parameters: { kind: "string" } },
+      { name: "tool_b", description: "B", parameters: { kind: "number" } },
+    ];
+    const result = toolsToJson(tools);
+    assert.equal(result.length, 2);
+    assert.equal(result[0].name, "tool_a");
+    assert.equal(result[1].name, "tool_b");
+  });
+});
+
+// ---------------------------------------------------------------
+// messagesToCC
+// ---------------------------------------------------------------
+
+describe("messagesToCC() — user messages", () => {
+  it("converts string content user message", () => {
+    const msgs = [{ role: "user", content: "hello" }];
+    const result = messagesToCC(msgs);
+    assert.equal(result.length, 1);
+    assert.equal(result[0].role, "user");
+    assert.equal(result[0].content, "hello");
+  });
+
+  it("passes through array content user message", () => {
+    const content = [{ type: "text", text: "hello" }];
+    const msgs = [{ role: "user", content }];
+    const result = messagesToCC(msgs);
+    assert.equal(result[0].role, "user");
+    assert.equal(result[0].content, content);
+  });
+});
+
+describe("messagesToCC() — assistant messages", () => {
+  it("converts text content", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [{ type: "text", text: "Hello from assistant" }],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.equal(result.length, 1);
+    assert.equal(result[0].role, "assistant");
+    assert.deepEqual(result[0].content, [
+      { type: "text", text: "Hello from assistant" },
+    ]);
+  });
+
+  it("converts thinking content to reasoning", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [{ type: "thinking", thinking: "Let me think..." }],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.deepEqual(result[0].content, [
+      { type: "reasoning", text: "Let me think..." },
+    ]);
+  });
+
+  it("converts toolCall content", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          {
+            type: "toolCall",
+            id: "call_123",
+            name: "read_file",
+            arguments: { path: "/tmp/test" },
+          },
+        ],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.deepEqual(result[0].content, [
+      {
+        type: "tool-call",
+        toolCallId: "call_123",
+        toolName: "read_file",
+        input: { path: "/tmp/test" },
+      },
+    ]);
+  });
+
+  it("converts mixed content (thinking + text + toolCall)", () => {
+    const msgs = [
+      {
+        role: "assistant",
+        content: [
+          { type: "thinking", thinking: "planning..." },
+          { type: "text", text: "result" },
+          { type: "toolCall", id: "t1", name: "ls", arguments: {} },
+        ],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.equal(result[0].role, "assistant");
+    assert.equal(result[0].content.length, 3);
+    assert.equal(result[0].content[0].type, "reasoning");
+    assert.equal(result[0].content[1].type, "text");
+    assert.equal(result[0].content[2].type, "tool-call");
+  });
+});
+
+describe("messagesToCC() — toolResult messages", () => {
+  it("converts successful tool result", () => {
+    const msgs = [
+      {
+        role: "toolResult",
+        toolCallId: "call_123",
+        toolName: "read_file",
+        isError: false,
+        content: [{ type: "text", text: "file contents here" }],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.equal(result.length, 1);
+    assert.equal(result[0].role, "tool");
+    assert.equal(result[0].content[0].type, "tool-result");
+    assert.equal(result[0].content[0].output.type, "text");
+    assert.equal(result[0].content[0].output.value, "file contents here");
+  });
+
+  it("converts error tool result", () => {
+    const msgs = [
+      {
+        role: "toolResult",
+        toolCallId: "call_456",
+        toolName: "bad_tool",
+        isError: true,
+        content: [{ type: "text", text: "something went wrong" }],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.equal(result[0].content[0].output.type, "error-text");
+    assert.equal(result[0].content[0].output.value, "something went wrong");
+  });
+
+  it("joins multiple text parts", () => {
+    const msgs = [
+      {
+        role: "toolResult",
+        toolCallId: "call_789",
+        toolName: "grep",
+        isError: false,
+        content: [
+          { type: "text", text: "line 1" },
+          { type: "text", text: "line 2" },
+        ],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.equal(result[0].content[0].output.value, "line 1\nline 2");
+  });
+});
+
+describe("messagesToCC() — full conversation", () => {
+  it("handles user → assistant(toolCall) → tool → assistant", () => {
+    const msgs = [
+      { role: "user", content: "read /tmp/test" },
+      {
+        role: "assistant",
+        content: [
+          { type: "thinking", thinking: "I will read the file" },
+          {
+            type: "toolCall",
+            id: "c1",
+            name: "read",
+            arguments: { path: "/tmp/test" },
+          },
+        ],
+      },
+      {
+        role: "toolResult",
+        toolCallId: "c1",
+        toolName: "read",
+        isError: false,
+        content: [{ type: "text", text: "hello world" }],
+      },
+      {
+        role: "assistant",
+        content: [{ type: "text", text: "The file contains: hello world" }],
+      },
+    ];
+    const result = messagesToCC(msgs);
+    assert.equal(result.length, 4);
+    assert.equal(result[0].role, "user");
+    assert.equal(result[1].role, "assistant");
+    assert.equal(result[1].content.length, 2);
+    assert.equal(result[2].role, "tool");
+    assert.equal(result[3].role, "assistant");
+    assert.equal(result[3].content[0].text, "The file contains: hello world");
+  });
+
+  it("handles empty message array", () => {
+    const result = messagesToCC([]);
+    assert.deepEqual(result, []);
+  });
+});