diff --git a/canvas/src/components/ConversationTraceModal.tsx b/canvas/src/components/ConversationTraceModal.tsx
index 41dd9f80..4dfd380f 100644
--- a/canvas/src/components/ConversationTraceModal.tsx
+++ b/canvas/src/components/ConversationTraceModal.tsx
@@ -13,7 +13,8 @@ interface Props {
   onClose: () => void;
 }
 
-function extractMessageText(body: Record<string, unknown> | null): string {
+/** Exported for unit testing — see ConversationTraceModal.test.ts */
+export function extractMessageText(body: Record<string, unknown> | null): string {
   if (!body) return "";
   try {
     // Simple task format from MCP server: {task: "..."}
@@ -84,6 +85,7 @@ export function ConversationTraceModal({ open, workspaceId: _workspaceId, onClos
     });
   }, [open, nodes]);
 
+  /** Exported for unit testing — see ConversationTraceModal.test.ts */
   const isA2A = (e: ActivityEntry) =>
     e.activity_type === "a2a_receive" || e.activity_type === "a2a_send";
 
diff --git a/canvas/src/components/__tests__/ConversationTraceModal.test.tsx b/canvas/src/components/__tests__/ConversationTraceModal.test.tsx
new file mode 100644
index 00000000..39d16a86
--- /dev/null
+++ b/canvas/src/components/__tests__/ConversationTraceModal.test.tsx
@@ -0,0 +1,156 @@
+// @vitest-environment jsdom
+/**
+ * Tests for ConversationTraceModal's extractMessageText helper.
+ *
+ * Covers: MCP simple task format, request params.message.parts extraction,
+ * response result.parts extraction, result.root.text extraction, plain string
+ * result, null input, malformed input, empty strings.
+ */
+import { describe, expect, it } from "vitest";
+import { extractMessageText } from "../ConversationTraceModal";
+
+describe("extractMessageText — MCP simple task format", () => {
+  it("extracts text from body.task field", () => {
+    const body = { task: "Deploy the agent to production" };
+    expect(extractMessageText(body)).toBe("Deploy the agent to production");
+  });
+
+  it("returns empty string when body is null", () => {
+    expect(extractMessageText(null)).toBe("");
+  });
+
+  it("returns empty string when body is undefined", () => {
+    expect(extractMessageText(undefined as unknown as null)).toBe("");
+  });
+});
+
+describe("extractMessageText — request params.message format", () => {
+  it("extracts text from params.message.parts[].text", () => {
+    const body = {
+      params: {
+        message: {
+          parts: [{ text: "Hello world" }],
+        },
+      },
+    };
+    expect(extractMessageText(body)).toBe("Hello world");
+  });
+
+  it("joins multiple parts with newlines", () => {
+    const body = {
+      params: {
+        message: {
+          parts: [
+            { text: "First part" },
+            { text: "Second part" },
+            { text: "Third part" },
+          ],
+        },
+      },
+    };
+    expect(extractMessageText(body)).toBe("First part\nSecond part\nThird part");
+  });
+
+  it("ignores parts without text field", () => {
+    const body = {
+      params: {
+        message: {
+          parts: [{ text: "Hello" }, { other: "field" }, { text: "World" }],
+        },
+      },
+    };
+    expect(extractMessageText(body)).toBe("Hello\nWorld");
+  });
+
+  it("returns empty string when params.message is absent", () => {
+    const body = { params: {} };
+    expect(extractMessageText(body)).toBe("");
+  });
+});
+
+describe("extractMessageText — response result format", () => {
+  it("extracts text from result.parts[].text", () => {
+    const body = {
+      result: {
+        parts: [{ text: "Agent response" }],
+      },
+    };
+    expect(extractMessageText(body)).toBe("Agent response");
+  });
+
+  it("extracts text from result.parts[].root.text", () => {
+    const body = {
+      result: {
+        parts: [{ root: { text: "Root response text" } }],
+      },
+    };
+    expect(extractMessageText(body)).toBe("Root response text");
+  });
+
+  it("prefers parts[].text over parts[].root.text", () => {
+    const body = {
+      result: {
+        parts: [
+          { text: "Direct text" },
+          { root: { text: "Root text" } },
+        ],
+      },
+    };
+    // Both are non-empty strings, so the first one wins (filter picks the first)
+    // The implementation: rText from rParts[0].text = "Direct text"
+    expect(extractMessageText(body)).toBe("Direct text");
+  });
+});
+
+describe("extractMessageText — plain string result", () => {
+  it("returns body.result when it is a plain string", () => {
+    const body = { result: "Simple string response" };
+    expect(extractMessageText(body)).toBe("Simple string response");
+  });
+});
+
+describe("extractMessageText — priority order", () => {
+  it("prefers task format over params format", () => {
+    const body = {
+      task: "Task text",
+      params: { message: { parts: [{ text: "Params text" }] } },
+    };
+    // Implementation: checks task first, returns if non-empty
+    expect(extractMessageText(body)).toBe("Task text");
+  });
+
+  it("prefers params format over result format", () => {
+    const body = {
+      params: { message: { parts: [{ text: "Params text" }] } },
+      result: { parts: [{ text: "Result text" }] },
+    };
+    // Implementation: checks params.message.parts first (after task)
+    expect(extractMessageText(body)).toBe("Params text");
+  });
+});
+
+describe("extractMessageText — error resilience", () => {
+  it("returns empty string on malformed input", () => {
+    expect(extractMessageText({})).toBe("");
+    expect(extractMessageText({ params: null })).toBe("");
+    expect(extractMessageText({ result: null })).toBe("");
+  });
+
+  it("returns empty string when all fields are absent", () => {
+    expect(extractMessageText({ random: "field" })).toBe("");
+  });
+
+  it("handles missing parts array gracefully", () => {
+    const body = { params: { message: {} } };
+    expect(extractMessageText(body)).toBe("");
+  });
+
+  it("handles parts with undefined text gracefully", () => {
+    const body = {
+      result: {
+        parts: [{ text: undefined }, { text: "valid" }],
+      },
+    };
+    expect(extractMessageText(body)).toBe("valid");
+  });
+});
diff --git a/canvas/src/components/__tests__/MissingKeysModal.test.tsx b/canvas/src/components/__tests__/MissingKeysModal.test.tsx
new file mode 100644
index 00000000..23db886f
--- /dev/null
+++ b/canvas/src/components/__tests__/MissingKeysModal.test.tsx
@@ -0,0 +1,69 @@
+// @vitest-environment jsdom
+/**
+ * Tests for MissingKeysModal's providerIdForModel helper.
+ *
+ * Covers: model match, no match, empty modelId, whitespace-only modelId,
+ * model with no required_env, models undefined, single vs multiple env vars,
+ * stable sort order for env var ordering.
+ */
+import { describe, expect, it } from "vitest";
+import { providerIdForModel } from "../MissingKeysModal";
+
+describe("providerIdForModel — match behavior", () => {
+  it("returns sorted-joined env vars when model is found", () => {
+    const models = [
+      { id: "claude-3-5-sonnet", name: "Claude 3.5 Sonnet", required_env: ["ANTHROPIC_API_KEY"] },
+    ];
+    expect(providerIdForModel("claude-3-5-sonnet", models)).toBe("ANTHROPIC_API_KEY");
+  });
+
+  it("returns null when model is not found", () => {
+    const models = [
+      { id: "claude-3-5-sonnet", name: "Claude 3.5 Sonnet", required_env: ["ANTHROPIC_API_KEY"] },
+    ];
+    expect(providerIdForModel("unknown-model", models)).toBeNull();
+  });
+
+  it("returns null when models is undefined", () => {
+    expect(providerIdForModel("claude-3-5-sonnet", undefined)).toBeNull();
+  });
+
+  it("returns null when modelId is empty string", () => {
+    const models = [{ id: "claude", name: "Claude", required_env: ["KEY"] }];
+    expect(providerIdForModel("", models)).toBeNull();
+  });
+
+  it("returns null when modelId is whitespace-only", () => {
+    const models = [{ id: "claude", name: "Claude", required_env: ["KEY"] }];
+    expect(providerIdForModel("   ", models)).toBeNull();
+  });
+
+  it("trims whitespace from modelId before matching", () => {
+    const models = [{ id: "claude", name: "Claude", required_env: ["KEY"] }];
+    expect(providerIdForModel("  claude  ", models)).toBe("KEY");
+  });
+});
+
+describe("providerIdForModel — required_env variations", () => {
+  it("returns null when model has no required_env", () => {
+    const models = [{ id: "local-model", name: "Local Model", required_env: [] }];
+    expect(providerIdForModel("local-model", models)).toBeNull();
+  });
+
+  it("returns null when model.required_env is undefined", () => {
+    const models = [{ id: "local-model", name: "Local Model" }] as Array<{
+      id: string;
+      name: string;
+      required_env?: string[];
+    }>;
+    expect(providerIdForModel("local-model", models)).toBeNull();
+  });
+
+  it("sorts and joins multiple required_env alphabetically", () => {
+    const models = [
+      { id: "openrouter", name: "OpenRouter", required_env: ["OPENAI_API_KEY", "ANTHROPIC_API_KEY"] },
+    ];
+    // Expected: alphabetically sorted = ANTHROPIC_API_KEY|OPENAI_API_KEY
+    expect(providerIdForModel("openrouter", models)).toBe("ANTHROPIC_API_KEY|OPENAI_API_KEY");
+  });
+});