diff --git a/packages/ai/src/native-tools.ts b/packages/ai/src/native-tools.ts
index fa8832af..99c2dbeb 100644
--- a/packages/ai/src/native-tools.ts
+++ b/packages/ai/src/native-tools.ts
@@ -99,7 +99,7 @@ export function resolveNativeTool(spec: CuaNativeToolSpec, model: Model<Api>, mo
 	const info = NATIVE_TOOL_INFO[spec.type];
 	if (!info) throw new Error(`unknown native tool type "${(spec as { type: string }).type}"`);
 	if (model.provider !== info.provider) {
-		throw new Error(`native tool "${spec.type}" requires an ${info.provider} model; got provider "${model.provider}"`);
+		throw new Error(`native tool "${spec.type}" requires an ${info.provider} model paired with mode "${info.mode}"; got provider "${model.provider}"`);
 	}
 	if (mode !== info.mode) {
 		throw new Error(`native tool "${spec.type}" requires mode "${info.mode}"; got "${mode}"`);
diff --git a/packages/ai/src/providers/common.ts b/packages/ai/src/providers/common.ts
index 6430fae2..3b667703 100644
--- a/packages/ai/src/providers/common.ts
+++ b/packages/ai/src/providers/common.ts
@@ -303,17 +303,19 @@ export interface ResponseThreadingDelta {
  * Anchors on the most recent assistant turn: returns its `responseId` and the
  * messages after it (the delta). An errored or aborted turn may carry a
  * `responseId` captured from an incomplete response the server never stored, so
- * its id is ignored. When the anchor has no usable `responseId`, or there is no
- * assistant turn yet, returns every message and no id so the caller replays the
- * full history, rather than chaining to a phantom id and pruning past it.
+ * its id is ignored. A turn produced by a different `api` (e.g. after a
+ * mid-session `-m` provider switch) is ignored too — its id would be foreign to
+ * the current provider. When the anchor has no usable `responseId`, or there is
+ * no assistant turn yet, returns every message and no id so the caller replays
+ * the full history, rather than chaining to a phantom id and pruning past it.
  */
-export function responseThreadingDelta(messages: readonly Message[]): ResponseThreadingDelta {
+export function responseThreadingDelta(messages: readonly Message[], api: Api): ResponseThreadingDelta {
 	for (let index = messages.length - 1; index >= 0; index -= 1) {
 		const message = messages[index]!;
 		if (message.role !== "assistant") continue;
 		const assistant = message as AssistantMessage;
 		const failed = assistant.stopReason === "error" || assistant.stopReason === "aborted";
-		const responseId = failed ? undefined : assistant.responseId;
+		const responseId = failed || assistant.api !== api ? undefined : assistant.responseId;
 		return responseId ? { previousResponseId: responseId, deltaMessages: messages.slice(index + 1) } : { deltaMessages: [...messages] };
 	}
 	return { deltaMessages: [...messages] };
diff --git a/packages/ai/src/providers/openai/provider.ts b/packages/ai/src/providers/openai/provider.ts
index cb8bc75d..bca616a3 100644
--- a/packages/ai/src/providers/openai/provider.ts
+++ b/packages/ai/src/providers/openai/provider.ts
@@ -29,7 +29,7 @@ export function threadRequest(
 	context: Context,
 	options: (ResponseThreadingOptions & { onPayload?: OnPayload }) | undefined,
 ): { context: Context; onPayload: OnPayload } {
-	const delta = responseThreadingEnabled(options) ? responseThreadingDelta(context.messages) : undefined;
+	const delta = responseThreadingEnabled(options) ? responseThreadingDelta(context.messages, OPENAI_CUA_RESPONSES_API) : undefined;
 	const previousResponseId = delta?.previousResponseId;
 	const messages = previousResponseId && delta ? delta.deltaMessages : context.messages;
 	const onPayload: OnPayload = async (payload, model) => {
diff --git a/packages/ai/src/providers/tzafon/provider.ts b/packages/ai/src/providers/tzafon/provider.ts
index db64cc90..95f31de9 100644
--- a/packages/ai/src/providers/tzafon/provider.ts
+++ b/packages/ai/src/providers/tzafon/provider.ts
@@ -76,7 +76,7 @@ export function buildTzafonRequestInput(model: Model<Api>, context: Context, opt
 		max_output_tokens: options?.maxTokens ?? model.maxTokens,
 	};
 	if (!responseThreadingEnabled(options)) return body;
-	const { previousResponseId, deltaMessages } = responseThreadingDelta(context.messages);
+	const { previousResponseId, deltaMessages } = responseThreadingDelta(context.messages, TZAFON_RESPONSES_API);
 	if (!previousResponseId) return body;
 	return { ...body, input: convertMessages(deltaMessages), previous_response_id: previousResponseId, store: true };
 }
diff --git a/packages/ai/test/native-tools.test.ts b/packages/ai/test/native-tools.test.ts
index fa815fc7..399bc498 100644
--- a/packages/ai/test/native-tools.test.ts
+++ b/packages/ai/test/native-tools.test.ts
@@ -35,7 +35,7 @@ describe("native tool validation", () => {
 
 	it("rejects native tools on non-anthropic models", () => {
 		expect(() => resolveCuaRuntimeSpec("openai:gpt-5.5", { nativeTool: { type: "computer_20260701" } })).toThrow(
-			/requires an anthropic model/,
+			/requires an anthropic model paired with mode "computer"/,
 		);
 	});
 });
diff --git a/packages/ai/test/openai-threading.test.ts b/packages/ai/test/openai-threading.test.ts
index 7ba25602..d4821d06 100644
--- a/packages/ai/test/openai-threading.test.ts
+++ b/packages/ai/test/openai-threading.test.ts
@@ -96,6 +96,25 @@ describe("openai threadRequest", () => {
 		expect(((await onPayload({}, model)) as Record<string, unknown>).previous_response_id).toBeUndefined();
 	});
 
+	it("never anchors previous_response_id on an assistant turn from a different api", async () => {
+		const ctx = multiTurnContext();
+		// A mid-session -m provider switch leaves the prior provider's turn (and its foreign id) as the anchor.
+		ctx.messages.push({
+			role: "assistant",
+			content: [{ type: "text", text: "done" }],
+			api: "anthropic-messages",
+			provider: "anthropic",
+			model: "claude-opus-4-8",
+			responseId: "msg_anthropic",
+			usage: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, totalTokens: 0, cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 } },
+			stopReason: "stop",
+			timestamp: 0,
+		});
+		const { context, onPayload } = threadRequest(ctx, undefined);
+		expect(context).toBe(ctx);
+		expect(((await onPayload({}, model)) as Record<string, unknown>).previous_response_id).toBeUndefined();
+	});
+
 	it("composes a caller onPayload on top of the threaded payload", async () => {
 		const { onPayload } = threadRequest(multiTurnContext(), {
 			onPayload: (payload) => ({ wrapped: payload }),
diff --git a/packages/ai/test/tzafon-threading.test.ts b/packages/ai/test/tzafon-threading.test.ts
index e7ba1f15..959b55c5 100644
--- a/packages/ai/test/tzafon-threading.test.ts
+++ b/packages/ai/test/tzafon-threading.test.ts
@@ -115,6 +115,25 @@ describe("buildTzafonRequestInput response threading", () => {
 		expect(screenshotImageUrls(body.input)).toHaveLength(TURNS);
 	});
 
+	it("replays full history when the latest assistant turn is from a different api", () => {
+		const context = multiTurnContext();
+		context.messages.push({
+			role: "assistant",
+			content: [{ type: "text", text: "done" }],
+			api: "anthropic-messages",
+			provider: "anthropic",
+			model: "claude-opus-4-8",
+			responseId: "msg_anthropic",
+			usage: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, totalTokens: 0, cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 } },
+			stopReason: "stop",
+			timestamp: 0,
+		});
+
+		const body = tzafon.buildTzafonRequestInput(model, context);
+		expect(body.previous_response_id).toBeUndefined();
+		expect(screenshotImageUrls(body.input)).toHaveLength(TURNS);
+	});
+
 	// Off-path screenshot count scales with turn count; on-path stays constant at one.
 	it("grows the payload per turn when off but stays flat when on", () => {
 		const counts = (turns: number, disable: boolean) => {
diff --git a/packages/cli/src/action/prompts.ts b/packages/cli/src/action/prompts.ts
index 6772c0b8..18b552a5 100644
--- a/packages/cli/src/action/prompts.ts
+++ b/packages/cli/src/action/prompts.ts
@@ -90,5 +90,5 @@ Be concise and factual. Do NOT perform any actions. Only observe and respond.`;
 }
 
 function urlPrompt(): string {
-	return `Report the current page URL. Use the url action to read it. Do not perform any other actions.`;
+	return `Report the current page URL. Use the url action to read it. Do not perform any other actions. Respond with only the bare URL, no markdown or other formatting.`;
 }
diff --git a/packages/cli/src/action/result.ts b/packages/cli/src/action/result.ts
index 61b81e36..e656b5cd 100644
--- a/packages/cli/src/action/result.ts
+++ b/packages/cli/src/action/result.ts
@@ -94,7 +94,7 @@ function extractFirstUrl(text: string): string | undefined {
 		/(?:https?:\/\/\S+|about:blank|file:\/\/\S+|chrome:\/\/\S+|chrome-extension:\/\/\S+|edge:\/\/\S+|brave:\/\/\S+)/gi,
 	);
 	if (!matches || matches.length === 0) return undefined;
-	return matches[matches.length - 1]!.replace(/[),.;!?]+$/, "");
+	return matches[matches.length - 1]!.replace(/[)*_`,.;!?]+$/, "");
 }
 
 export function formatCompact(r: ActionResult): string {
diff --git a/packages/cli/src/cli-harness.ts b/packages/cli/src/cli-harness.ts
index 9c028047..51a36c27 100644
--- a/packages/cli/src/cli-harness.ts
+++ b/packages/cli/src/cli-harness.ts
@@ -12,6 +12,7 @@ import {
 	type CuaNativeToolSpec,
 	parseCuaModelRef,
 	requireCuaEnvApiKey,
+	resolveCuaRuntimeSpec,
 } from "@onkernel/cua-ai";
 import { parseArgs } from "node:util";
 import { stderr, stdout } from "node:process";
@@ -29,6 +30,8 @@ import {
 	formatRelativeAge,
 	listNamedSessions,
 	type NamedSessionMetadata,
+	readNamedSession,
+	recordSessionModel,
 	recordTranscriptPath,
 	shortKernelId,
 	startNamedSession,
@@ -362,10 +365,24 @@ export interface SetupHarnessRuntimeOptions {
 	skipDiskSession?: boolean;
 }
 
+/** Default -m/--mode/--native-tool from a named session's stored values when not passed explicitly. */
+export function applyNamedSessionDefaults(flags: HarnessCliFlags, meta: NamedSessionMetadata): HarnessCliFlags {
+	return {
+		...flags,
+		model: flags.model ?? meta.model,
+		mode: flags.mode ?? meta.mode,
+		nativeTool: flags.nativeTool ?? meta.native_tool,
+	};
+}
+
 async function setupHarnessRuntime(
 	flags: HarnessCliFlags,
 	opts: SetupHarnessRuntimeOptions = {},
 ): Promise<HarnessRuntime> {
+	if (flags.namedSession) {
+		const named = await readNamedSession(flags.namedSession);
+		if (named) flags = applyNamedSessionDefaults(flags, named);
+	}
 	const auth = resolveAuth(flags);
 	const cwd = process.cwd();
 	const env = new NodeExecutionEnv({ cwd });
@@ -380,6 +397,7 @@ async function setupHarnessRuntime(
 	// never leaves an orphaned browser behind.
 	const mode = parseMode(flags.mode);
 	const nativeTool = parseNativeTool(flags.nativeTool);
+	resolveCuaRuntimeSpec(auth.modelRef, { mode, nativeTool });
 
 	const provisioned = await provisionForFlags(flags, auth);
 	try {
@@ -429,6 +447,11 @@ async function finishHarnessRuntime(
 		});
 		if (provisioned.named) {
 			await recordTranscriptPath(provisioned.named.name, resolved.transcriptPath);
+			await recordSessionModel(provisioned.named.name, {
+				model: auth.modelRef,
+				mode: flags.mode,
+				native_tool: flags.nativeTool,
+			});
 		}
 		if (flags.verbose) {
 			stderr.write(`[cua] session=${resolved.transcriptPath}\n`);
@@ -653,6 +676,7 @@ export async function runSessionSubcommand(args: string[], flags: HarnessCliFlag
 				browserTimeoutSeconds: flags.browserTimeout,
 				profileSelector: flags.browserProfile,
 				saveProfileChanges: flags.profileSaveChanges,
+				model: flags.model ? resolveCuaModelRef(flags.model) : undefined,
 			});
 			stdout.write(`name=${meta.name}\n`);
 			stdout.write(`kernel_session_id=${browser.session_id}\n`);
diff --git a/packages/cli/src/harness-named-sessions.ts b/packages/cli/src/harness-named-sessions.ts
index 9b703d3d..663b91b9 100644
--- a/packages/cli/src/harness-named-sessions.ts
+++ b/packages/cli/src/harness-named-sessions.ts
@@ -19,6 +19,10 @@ export interface NamedSessionMetadata {
 	live_url?: string;
 	profile_id?: string;
 	transcript_path?: string;
+	/** Model ref last used with this session; chained invocations without -m default to it. */
+	model?: string;
+	mode?: string;
+	native_tool?: string;
 	created_at: number;
 }
 
@@ -99,6 +103,8 @@ export interface StartNamedSessionOptions {
 	/** Profile id or name (created if missing). Same semantics as `--profile`. */
 	profileSelector?: string;
 	saveProfileChanges?: boolean;
+	/** Canonical model ref to seed the session with (same semantics as `-m`). */
+	model?: string;
 }
 
 export interface StartNamedSessionResult {
@@ -138,6 +144,7 @@ export async function startNamedSession(opts: StartNamedSessionOptions): Promise
 		kernel_session_id: browser.session_id,
 		live_url: browser.browser_live_view_url,
 		profile_id: profileId,
+		model: opts.model,
 		created_at: Date.now(),
 	};
 	const metadataPath = await writeNamedSession(meta);
@@ -232,6 +239,20 @@ export async function recordTranscriptPath(name: string, transcriptPath: string)
 	await writeNamedSession(meta);
 }
 
+/** Persist the model/mode/native-tool used with a named session so chained invocations reuse them. */
+export async function recordSessionModel(
+	name: string,
+	runtime: { model: string; mode?: string; native_tool?: string },
+): Promise<void> {
+	const meta = await readNamedSession(name);
+	if (!meta) return;
+	if (meta.model === runtime.model && meta.mode === runtime.mode && meta.native_tool === runtime.native_tool) return;
+	meta.model = runtime.model;
+	meta.mode = runtime.mode;
+	meta.native_tool = runtime.native_tool;
+	await writeNamedSession(meta);
+}
+
 export function shortKernelId(id: string): string {
 	return id.length > 10 ? `${id.slice(0, 8)}…` : id;
 }
diff --git a/packages/cli/test/action-result.test.ts b/packages/cli/test/action-result.test.ts
new file mode 100644
index 00000000..f1b25d11
--- /dev/null
+++ b/packages/cli/test/action-result.test.ts
@@ -0,0 +1,25 @@
+import { describe, expect, it } from "vitest";
+import { parseResult } from "../src/action/result";
+
+describe("parseResult url extraction", () => {
+	it("passes through a plain url", () => {
+		const res = parseResult("url", "https://quotes.toscrape.com/page/2/", [], 10);
+		expect(res.status).toBe("ok");
+		expect(res.url).toBe("https://quotes.toscrape.com/page/2/");
+	});
+
+	it("strips markdown bold markers", () => {
+		const res = parseResult("url", "**https://quotes.toscrape.com/page/2/**", [], 10);
+		expect(res.url).toBe("https://quotes.toscrape.com/page/2/");
+	});
+
+	it("strips wrapping backticks", () => {
+		const res = parseResult("url", "`https://example.com/path`", [], 10);
+		expect(res.url).toBe("https://example.com/path");
+	});
+
+	it("strips trailing punctuation", () => {
+		const res = parseResult("url", "The current URL is https://example.com/page.", [], 10);
+		expect(res.url).toBe("https://example.com/page");
+	});
+});
diff --git a/packages/cli/test/cli-harness-validation.test.ts b/packages/cli/test/cli-harness-validation.test.ts
new file mode 100644
index 00000000..c8f20ce3
--- /dev/null
+++ b/packages/cli/test/cli-harness-validation.test.ts
@@ -0,0 +1,67 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { type HarnessCliFlags, runActionCommand } from "../src/cli-harness";
+import { provisionBrowser } from "../src/harness-browser";
+
+vi.mock("../src/harness-browser", () => ({ provisionBrowser: vi.fn() }));
+
+function flagsWith(overrides: Partial<HarnessCliFlags>): HarnessCliFlags {
+	return {
+		verbose: false,
+		profileSaveChanges: false,
+		continueLatest: false,
+		resumePicker: false,
+		noSession: true,
+		noSkills: true,
+		debugTui: false,
+		jsonlIncludeDeltas: false,
+		jsonlIncludeImages: false,
+		playwright: false,
+		skillPaths: [],
+		...overrides,
+	};
+}
+
+describe("mode/native-tool validation before provisioning", () => {
+	beforeEach(() => {
+		vi.stubEnv("KERNEL_API_KEY", "test-kernel-key");
+		vi.stubEnv("ANTHROPIC_API_KEY", "test-anthropic-key");
+		vi.stubEnv("OPENAI_API_KEY", "test-openai-key");
+		vi.stubEnv("GOOGLE_API_KEY", "test-google-key");
+	});
+
+	afterEach(() => {
+		vi.unstubAllEnvs();
+		vi.mocked(provisionBrowser).mockClear();
+	});
+
+	it("rejects a native tool whose mode conflicts without provisioning a browser", async () => {
+		await expect(
+			runActionCommand("url", [], flagsWith({
+				model: "anthropic:claude-opus-4-8",
+				mode: "hybrid",
+				nativeTool: "computer_20260701",
+			})),
+		).rejects.toThrow('native tool "computer_20260701" requires mode "computer"; got "hybrid"');
+		expect(provisionBrowser).not.toHaveBeenCalled();
+	});
+
+	it("rejects a native tool on a non-anthropic model without provisioning a browser", async () => {
+		await expect(
+			runActionCommand("url", [], flagsWith({
+				model: "openai:gpt-5.5",
+				nativeTool: "computer_20260701",
+			})),
+		).rejects.toThrow('native tool "computer_20260701" requires an anthropic model paired with mode "computer"; got provider "openai"');
+		expect(provisionBrowser).not.toHaveBeenCalled();
+	});
+
+	it("rejects an unsupported provider/mode pair without provisioning a browser", async () => {
+		await expect(
+			runActionCommand("url", [], flagsWith({
+				model: "google:gemini-3-flash-preview",
+				mode: "browser",
+			})),
+		).rejects.toThrow('provider "google" does not support mode "browser" (computer only)');
+		expect(provisionBrowser).not.toHaveBeenCalled();
+	});
+});
diff --git a/packages/cli/test/harness-named-sessions.test.ts b/packages/cli/test/harness-named-sessions.test.ts
new file mode 100644
index 00000000..f8db3597
--- /dev/null
+++ b/packages/cli/test/harness-named-sessions.test.ts
@@ -0,0 +1,83 @@
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { mkdtempSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { applyNamedSessionDefaults, type HarnessCliFlags } from "../src/cli-harness";
+import {
+	type NamedSessionMetadata,
+	readNamedSession,
+	recordSessionModel,
+	writeNamedSession,
+} from "../src/harness-named-sessions";
+
+const originalXdg = process.env.XDG_DATA_HOME;
+
+function baseMeta(overrides: Partial<NamedSessionMetadata> = {}): NamedSessionMetadata {
+	return { name: "foo", kernel_session_id: "ks_123", created_at: Date.now(), ...overrides };
+}
+
+function baseFlags(overrides: Partial<HarnessCliFlags> = {}): HarnessCliFlags {
+	return {
+		verbose: false,
+		profileSaveChanges: false,
+		continueLatest: false,
+		resumePicker: false,
+		noSession: false,
+		noSkills: false,
+		debugTui: false,
+		jsonlIncludeDeltas: false,
+		jsonlIncludeImages: false,
+		playwright: false,
+		namedSession: "foo",
+		skillPaths: [],
+		...overrides,
+	};
+}
+
+describe("named session model persistence", () => {
+	beforeEach(() => {
+		process.env.XDG_DATA_HOME = mkdtempSync(join(tmpdir(), "cua-cli-named-"));
+	});
+
+	afterEach(() => {
+		if (originalXdg === undefined) delete process.env.XDG_DATA_HOME;
+		else process.env.XDG_DATA_HOME = originalXdg;
+	});
+
+	it("records the model/mode/native-tool onto the metadata file", async () => {
+		await writeNamedSession(baseMeta());
+		await recordSessionModel("foo", { model: "anthropic:claude-opus-4-8", mode: "hybrid", native_tool: "computer_20260701" });
+		const meta = await readNamedSession("foo");
+		expect(meta?.model).toBe("anthropic:claude-opus-4-8");
+		expect(meta?.mode).toBe("hybrid");
+		expect(meta?.native_tool).toBe("computer_20260701");
+	});
+
+	it("overwrites a previously recorded model on an explicit switch", async () => {
+		await writeNamedSession(baseMeta({ model: "openai:gpt-5.5" }));
+		await recordSessionModel("foo", { model: "anthropic:claude-opus-4-8", mode: "hybrid" });
+		const meta = await readNamedSession("foo");
+		expect(meta?.model).toBe("anthropic:claude-opus-4-8");
+		expect(meta?.mode).toBe("hybrid");
+	});
+
+	it("is a no-op for an unknown session", async () => {
+		await recordSessionModel("missing", { model: "openai:gpt-5.5" });
+		expect(await readNamedSession("missing")).toBeUndefined();
+	});
+
+	it("defaults flags from the stored session model when -m is omitted", () => {
+		const meta = baseMeta({ model: "anthropic:claude-opus-4-8", mode: "hybrid", native_tool: "computer_20260701" });
+		const flags = applyNamedSessionDefaults(baseFlags(), meta);
+		expect(flags.model).toBe("anthropic:claude-opus-4-8");
+		expect(flags.mode).toBe("hybrid");
+		expect(flags.nativeTool).toBe("computer_20260701");
+	});
+
+	it("keeps explicit flags over stored session values", () => {
+		const meta = baseMeta({ model: "anthropic:claude-opus-4-8", mode: "hybrid" });
+		const flags = applyNamedSessionDefaults(baseFlags({ model: "openai:gpt-5.5", mode: "browser" }), meta);
+		expect(flags.model).toBe("openai:gpt-5.5");
+		expect(flags.mode).toBe("browser");
+	});
+});