Add verified browser action plans - #65
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Cursor Bugbot has reviewed your changes using high effort and found 2 potential issues.
Autofix Details
Bugbot Autofix prepared fixes for both issues found in the latest run.
- ✅ Fixed: Batch summary ignores failed waits
- The batch status now always surfaces failed browser waits before action-plan outcomes, so mixed batches no longer hide wait failures.
- ✅ Fixed: Missing TSDoc on exported formatter
- Added TSDoc to
formatBrowserActResultdescribing its purpose, inputs, and why diff output is truncated versus structured details.
- Added TSDoc to
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diff --git a/packages/agent/src/tools.ts b/packages/agent/src/tools.ts
--- a/packages/agent/src/tools.ts
+++ b/packages/agent/src/tools.ts
@@ -199,17 +199,15 @@
const acts = readResults.flatMap((read) => read.type === "browser_act" ? [read.result] : []);
const waits = readResults.flatMap((read) => read.type === "browser_wait_for" ? [read.result] : []);
const failedWait = ["interrupted", "timed_out", "unverifiable"].find((status) => waits.some((wait) => wait.status === status));
- const statusText = acts.length > 0
+ const actStatusText = acts.length > 0
? acts.some((act) => act.outcome === "didnt")
? "Browser action plan did not satisfy its expectations."
: acts.every((act) => act.outcome === "worked")
? "Browser action plan worked."
: "Browser action plan outcome is unknown."
- : waits.length === 0
- ? "Actions executed successfully."
- : failedWait
- ? `Browser condition ${failedWait}.`
- : "Browser condition satisfied.";
+ : undefined;
+ const waitStatusText = waits.length === 0 ? undefined : failedWait ? `Browser condition ${failedWait}.` : "Browser condition satisfied.";
+ const statusText = failedWait ? `Browser condition ${failedWait}.` : actStatusText ?? waitStatusText ?? "Actions executed successfully.";
return { content, details: { statusText, readResults } };
}
@@ -287,6 +285,11 @@
return [`wait_for: ${result.status}/${result.evidence}${reason} after ${result.elapsed_ms}ms`, ...result.details].join("\n");
}
+/**
+ * Formats a browser action plan result for model-facing tool text output.
+ * Includes per-step outcomes and successor details while capping successor
+ * diff lines so large diffs stay in structured `readResults`, not tool text.
+ */
export function formatBrowserActResult(result: BrowserActResult): string {
const lines = [`browser_act: ${result.outcome}`];
if (result.stopped_at !== undefined) lines.push(`stopped_at: ${result.stopped_at} (${result.stop_reason ?? "unknown"})`);You can send follow-ups to the cloud agent here.
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Cursor Bugbot has reviewed your changes using high effort and found 2 potential issues.
Autofix Details
Bugbot Autofix prepared fixes for both issues found in the latest run.
- ✅ Fixed: Baseline wait aborts navigation expects
- I allowed location expectations with an explicit pre-action baseline to continue past initial navigation drift so the poll loop can mark successful navigations as newly verified.
- ✅ Fixed: Mixed batch ignores wait failures
- I updated mixed-batch execution to stop after browser_wait_for results with interrupted, timed_out, or unverifiable statuses, matching the existing browser_act stop behavior.
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diff --git a/packages/agent/src/translator/browser-wait.ts b/packages/agent/src/translator/browser-wait.ts
--- a/packages/agent/src/translator/browser-wait.ts
+++ b/packages/agent/src/translator/browser-wait.ts
@@ -109,7 +109,9 @@
}
const initial = evaluateBrowserExpectation(options.expect, baseline, baseline, runtime.resolveRef);
if (!baseline.complete) return terminal("unverifiable", "unverifiable", initial, initial, started, now(), "incomplete_observation");
- if (runtime.liveNavigationEpoch(targetId) !== baseline.navigationEpoch || [...baseline.generations].some(([key, generation]) => runtime.liveGeneration(key) !== generation)) return terminal("interrupted", "unverifiable", initial, initial, started, now(), "navigation");
+ const baselineNavigated = runtime.liveNavigationEpoch(targetId) !== baseline.navigationEpoch || [...baseline.generations].some(([key, generation]) => runtime.liveGeneration(key) !== generation);
+ const allowLocationRecovery = !!options.baseline && isLocationExpectation(options.expect);
+ if (baselineNavigated && !allowLocationRecovery) return terminal("interrupted", "unverifiable", initial, initial, started, now(), "navigation");
if (expired()) return timedOut(started, now());
if (initial.reason === "stale_ref") return terminal("interrupted", "unverifiable", initial, initial, started, now(), initial.reason);
if (initial.truth === true && !options.baseline) return terminal("satisfied", "preexisting", initial, initial, started, now());
diff --git a/packages/agent/src/translator/translator.ts b/packages/agent/src/translator/translator.ts
--- a/packages/agent/src/translator/translator.ts
+++ b/packages/agent/src/translator/translator.ts
@@ -136,7 +136,10 @@
await flush();
const reads = await this.browser().execute(action);
result.readResults.push(...reads);
- if (action.type === "browser_act" && reads.some((read) => read.type === "browser_act" && read.result.stop_reason)) break;
+ if (
+ (action.type === "browser_act" && reads.some((read) => read.type === "browser_act" && read.result.stop_reason)) ||
+ (action.type === "browser_wait_for" && reads.some((read) => read.type === "browser_wait_for" && (read.result.status === "interrupted" || read.result.status === "timed_out" || read.result.status === "unverifiable")))
+ ) break;
continue;
}
switch (action.type) {
diff --git a/packages/agent/test/browser-wait.test.ts b/packages/agent/test/browser-wait.test.ts
--- a/packages/agent/test/browser-wait.test.ts
+++ b/packages/agent/test/browser-wait.test.ts
@@ -131,6 +131,23 @@
expect(result).toMatchObject({ status: "satisfied", evidence: "newly_verified" });
});
+ it("allows location expectations to verify when a pre-action baseline is already stale", async () => {
+ let time = 0;
+ const baseline = observation([], true, { url: "https://a.test/start", generations: new Map([["page", 0]]) });
+ const result = await waitForBrowserExpectation({
+ selectTarget: async () => "page",
+ observeTarget: async () => observation([], true, { url: "https://a.test/done", navigationEpoch: 1, generations: new Map([["page", 1]]) }),
+ dialogCount: () => 0,
+ targetExists: async () => true,
+ liveGeneration: () => 1,
+ liveNavigationEpoch: () => 1,
+ resolveRef: missingRef,
+ now: () => time,
+ delay: async (ms) => { time += ms; },
+ }, { expect: { type: "url", changed: true }, baseline, targetId: "page", timeoutMs: 20, pollMs: 10 });
+ expect(result).toMatchObject({ status: "satisfied", evidence: "newly_verified" });
+ });
+
it("reports navigation instead of timeout when a location change lands at the deadline", async () => {
let time = 0, reads = 0;
const result = await waitForBrowserExpectation({
diff --git a/packages/agent/test/translator-browser.test.ts b/packages/agent/test/translator-browser.test.ts
--- a/packages/agent/test/translator-browser.test.ts
+++ b/packages/agent/test/translator-browser.test.ts
@@ -300,6 +300,30 @@
await translator.executeBatch([{ type: "browser_act", steps: [{ type: "wait" }] }, { type: "browser_text" }]);
expect(executed).toEqual(["browser_act"]);
});
+
+ it.each(["interrupted", "timed_out", "unverifiable"] as const)("stops a mixed batch after a browser_wait_for %s result", async (status) => {
+ const { client } = createClient();
+ const executed: string[] = [];
+ const result: BrowserWaitForResult = {
+ status,
+ evidence: status === "timed_out" ? "failed" : "unverifiable",
+ initial: { truth: false, details: ["before"] },
+ final: { truth: false, details: ["after"] },
+ elapsed_ms: 1,
+ ...(status === "interrupted" ? { reason: "navigation" } : {}),
+ details: [],
+ };
+ const executor = { execute: async (action: CuaBrowserAction) => {
+ executed.push(action.type);
+ return action.type === "browser_wait_for" ? [{ type: "browser_wait_for", result } as BatchReadResult] : [];
+ } } as unknown as BrowserExecutor;
+ const translator = new InternalComputerTranslator({ browser, client, createBrowserExecutor: () => executor });
+ await translator.executeBatch([
+ { type: "browser_wait_for", expect: { type: "text", text: "Ready" } },
+ { type: "browser_text" },
+ ]);
+ expect(executed).toEqual(["browser_wait_for"]);
+ });
});
describe("InternalComputerTranslator computer additions", () => {You can send follow-ups to the cloud agent here.
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Cursor Bugbot has reviewed your changes using high effort and found 2 potential issues.
Autofix Details
Bugbot Autofix prepared fixes for both issues found in the latest run.
- ✅ Fixed: Stop reason masks failed expectation
- I reordered stop-reason resolution so failed semantic waits are classified before post-action observation completeness fallbacks.
- ✅ Fixed: Misleading stopped_at on successor race
- I removed the late-boundary fallback that assigned
stopped_atduring successor collection when no step loop interruption occurred.
- I removed the late-boundary fallback that assigned
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diff --git a/packages/agent/src/translator/browser-act.ts b/packages/agent/src/translator/browser-act.ts
--- a/packages/agent/src/translator/browser-act.ts
+++ b/packages/agent/src/translator/browser-act.ts
@@ -88,13 +88,14 @@
const postBoundary = after && afterTargets ? boundary(before, after, targets, afterTargets, dialogs, runtime) : undefined;
if (after && afterTargets) { current = after; targets = afterTargets; dialogs = runtime.dialogCount(); }
- stopReason = (!after?.complete ? "control_flow" : undefined)
- ?? postBoundary
+ stopReason = postBoundary
?? waitStopReason(waitResult)
?? (stale ? "stale_ref"
: actionError ? "action_failed"
: expectation?.status === "failed" ? "expectation_failed"
- : expectation?.status === "preexisting" || expectation?.status === "unverifiable" || !after ? "control_flow" : undefined);
+ : undefined)
+ ?? (!after?.complete ? "control_flow" : undefined)
+ ?? (expectation?.status === "preexisting" || expectation?.status === "unverifiable" || !after ? "control_flow" : undefined);
if (stopReason) { stoppedAt = index; break; }
}
@@ -123,7 +124,6 @@
current = observed; targets = successorTargets; dialogs = runtime.dialogCount();
if (lateBoundary) {
stopReason ??= lateBoundary;
- stoppedAt ??= finalStepIndex;
successorError = new Error(`${lateBoundary} changed successor observation`);
continue;
}
diff --git a/packages/agent/test/translator-browser.test.ts b/packages/agent/test/translator-browser.test.ts
--- a/packages/agent/test/translator-browser.test.ts
+++ b/packages/agent/test/translator-browser.test.ts
@@ -156,6 +156,13 @@
expect(rt.dispatched).toEqual(["click"]);
});
+ it("keeps expectation_failed when post-action observation fails", async () => {
+ const result = await runBrowserAct({ type: "browser_act", steps: [{ type: "click", ref: "e1", expect: { type: "text", text: "Missing" } }] }, runtime([
+ observation("before"), observation("before"), observation("after"),
+ ], [waitResult("failed")], { failObservationAt: 2 }));
+ expect(result).toMatchObject({ outcome: "didnt", stopped_at: 0, stop_reason: "expectation_failed", steps: [{ outcome: "didnt", expectation: { status: "failed" } }] });
+ });
+
it("stops on a stale ref without dispatching later steps", async () => {
const rt = runtime([observation("before"), observation("before"), observation("successor")], [], { dispatchError: new Error("ref e1 is stale") });
const result = await runBrowserAct({ type: "browser_act", steps: [{ type: "click", ref: "e1" }, { type: "type", text: "no" }] }, rt);
@@ -190,6 +197,7 @@
observation("before"), observation("before"), observation("after"), observation("stale"), observation("stable"),
], [waitResult("newly_verified")], { targets: [["target-1"], ["target-1"], ["target-1"], ["target-1", "target-2"], ["target-1", "target-2"]] }));
expect(result).toMatchObject({ stop_reason: "control_flow", successor: { status: "observed", title: "stable", text: "stable" } });
+ expect(result).not.toHaveProperty("stopped_at");
});
it("preserves a timed-out final expectation when the successor satisfies it", async () => {You can send follow-ups to the cloud agent here.
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✅ Bugbot reviewed your changes and found no new issues!
1 issue from previous review remains unresolved.
Comment @cursor review or bugbot run to trigger another review on this PR
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Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.
Autofix Details
Bugbot Autofix prepared a fix for the issue found in the latest run.
- ✅ Fixed: Final expect upgrade leaves stop reason
- When successor evaluation upgrades an unverifiable final expectation to true, runBrowserAct now clears the inherited stop_reason/stopped_at so the verified result reports worked consistently.
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diff --git a/packages/agent/src/translator/browser-act.ts b/packages/agent/src/translator/browser-act.ts
--- a/packages/agent/src/translator/browser-act.ts
+++ b/packages/agent/src/translator/browser-act.ts
@@ -131,11 +131,16 @@
if (!observed.complete) throw new Error("successor observation incomplete");
if (action.expect && finalExpectation && finalExpectation.status !== "failed") {
const evaluation = runtime.evaluate(action.expect, observed, baseline);
+ const priorFinalStatus = finalExpectation.status;
finalExpectation = {
status: evaluation.truth === true ? finalExpectation.before === true ? "preexisting" : "newly_verified" : evaluation.truth === false ? "failed" : "unverifiable",
before: finalExpectation.before, after: evaluation.truth,
details: [...finalExpectation.details, ...evaluation.details.map((detail) => `successor: ${detail}`)],
};
+ if (evaluation.truth === true && priorFinalStatus === "unverifiable") {
+ stopReason = undefined;
+ stoppedAt = undefined;
+ }
if (evaluation.truth !== true) {
stopReason = evaluation.truth === false ? "expectation_failed" : "control_flow";
stoppedAt = finalStepIndex;
diff --git a/packages/agent/test/translator-browser.test.ts b/packages/agent/test/translator-browser.test.ts
--- a/packages/agent/test/translator-browser.test.ts
+++ b/packages/agent/test/translator-browser.test.ts
@@ -199,6 +199,15 @@
expect(result).toMatchObject({ outcome: "didnt", stop_reason: "expectation_failed", final_expectation: { status: "failed", after: false }, successor: { status: "observed", title: "after" } });
});
+ it("clears an unverifiable final stop reason when successor verification succeeds", async () => {
+ const result = await runBrowserAct({ type: "browser_act", steps: [{ type: "wait" }], expect: { type: "url", contains: "after" } }, runtime([
+ observation("before"), observation("before"), observation("after"), observation("after"),
+ ], [waitResult("unverifiable")]));
+ expect(result).toMatchObject({ outcome: "worked", final_expectation: { status: "newly_verified", after: true }, successor: { status: "observed", title: "after" } });
+ expect(result).not.toHaveProperty("stop_reason");
+ expect(result).not.toHaveProperty("stopped_at");
+ });
+
it("does not report incomplete successor observations as authoritative", async () => {
const incomplete = { ...observation("after"), complete: false };
const result = await runBrowserAct({ type: "browser_act", steps: [{ type: "click", ref: "e1", expect: { type: "text", text: "Done" } }] }, runtime([You can send follow-ups to the cloud agent here.
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Cursor Bugbot has reviewed your changes using high effort and found 2 potential issues.
Autofix Details
Bugbot Autofix prepared fixes for both issues found in the latest run.
- ✅ Fixed: Failed step expects misreported global timeout
- I only treat timed-out semantic waits as timeouts when evidence is not failed, so failed waits now report expectation_failed and still attempt successor observation.
- ✅ Fixed: Worked act still skips batch
- Batch stopping now ignores browser_act stop_reason when that act outcome is worked, so later independent actions in mixed batches continue executing.
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diff --git a/packages/agent/src/index.ts b/packages/agent/src/index.ts
--- a/packages/agent/src/index.ts
+++ b/packages/agent/src/index.ts
@@ -10,7 +10,19 @@
export type {
BatchExecutionResult,
BatchReadResult,
+ BrowserActExpectationEvidence,
+ BrowserActExpectationStatus,
+ BrowserActObservedSuccessor,
+ BrowserActOutcome,
+ BrowserActResult,
+ BrowserActStepResult,
+ BrowserActStopReason,
+ BrowserActSuccessor,
+ BrowserActUnavailableSuccessor,
BrowserExpectationEvidence,
+ BrowserExpectationState,
+ BrowserObservationDiff,
+ BrowserObservationDiffEntry,
BrowserWaitForResult,
BrowserWaitReason,
} from "./translator/types";
diff --git a/packages/agent/src/tools.ts b/packages/agent/src/tools.ts
--- a/packages/agent/src/tools.ts
+++ b/packages/agent/src/tools.ts
@@ -16,8 +16,12 @@
} from "@onkernel/cua-ai";
import { InternalComputerTranslator, type KernelBrowser } from "./translator/translator";
import type { AgentTool, AgentToolResult } from "@earendil-works/pi-agent-core";
-import type { BrowserWaitForResult } from "./translator/types";
+import type { BrowserActResult, BrowserWaitForResult } from "./translator/types";
+const BROWSER_ACT_DIFF_ENTRY_LIMIT = 200;
+const BROWSER_ACT_DIFF_CHAR_LIMIT = 20_000;
+const BROWSER_ACT_RESULT_CHAR_LIMIT = 50_000;
+
export interface ComputerToolOptions {
browser: KernelBrowser;
client: Kernel;
@@ -41,6 +45,7 @@
| { type: "cursor_position"; x: number; y: number }
| { type: "browser_text"; label: string; bytes: number }
| { type: "browser_wait_for"; result: BrowserWaitForResult }
+ | { type: "browser_act"; result: BrowserActResult }
>;
}
@@ -179,6 +184,9 @@
} else if (read.type === "browser_wait_for") {
readResults.push(read);
content.push({ type: "text", text: formatBrowserWaitResult(read.result) });
+ } else if (read.type === "browser_act") {
+ readResults.push(read);
+ content.push({ type: "text", text: formatBrowserActResult(read.result) });
} else {
readResults.push({ type: "screenshot", bytes: read.data.length });
content.push({ type: "image", data: read.data.toString("base64"), mimeType: read.mimeType });
@@ -194,13 +202,18 @@
} catch (err) {
throw new Error(`Actions failed: ${errorMessage(err)}`, { cause: err });
}
+ const acts = readResults.flatMap((read) => read.type === "browser_act" ? [read.result] : []);
const waits = readResults.flatMap((read) => read.type === "browser_wait_for" ? [read.result] : []);
const failedWait = ["interrupted", "timed_out", "unverifiable"].find((status) => waits.some((wait) => wait.status === status));
- let statusText = waits.length === 0
- ? "Actions executed successfully."
+ let statusText = acts.some((act) => act.outcome === "didnt")
+ ? "Browser action plan did not satisfy its expectations."
: failedWait
? `Browser condition ${failedWait}.`
- : "Browser condition satisfied.";
+ : acts.some((act) => act.outcome === "unknown")
+ ? "Browser action plan outcome is unknown."
+ : acts.length > 0
+ ? "Browser action plan worked."
+ : waits.length > 0 ? "Browser condition satisfied." : "Actions executed successfully.";
if (skippedActions) {
const skipped = `${skippedActions} subsequent action${skippedActions === 1 ? " was" : "s were"} skipped.`;
statusText = `${statusText} ${skipped}`;
@@ -290,6 +303,52 @@
return [`wait_for: ${result.status}/${result.evidence}${reason} after ${result.elapsed_ms}ms`, ...result.details].join("\n");
}
+/** Format model-facing plan feedback with bounded diff entries, diff characters, and total characters. */
+export function formatBrowserActResult(result: BrowserActResult): string {
+ const lines = [`browser_act: ${result.outcome}`];
+ if (result.stopped_at !== undefined) lines.push(`stopped_at: ${result.stopped_at} (${result.stop_reason ?? "unknown"})`);
+ for (const step of result.steps) {
+ lines.push(`step ${step.index} ${step.type}: ${step.outcome} — ${step.diagnostics.join("; ")}`);
+ for (const diagnostic of step.expectation?.diagnostics ?? []) lines.push(` ${diagnostic}`);
+ }
+ if (result.final_expectation) {
+ lines.push(`final expectation: ${result.final_expectation.status}`);
+ for (const diagnostic of result.final_expectation.diagnostics) lines.push(` ${diagnostic}`);
+ }
+ if (result.successor.status === "unavailable") {
+ lines.push(`successor unavailable: ${result.successor.error}`);
+ return boundedBrowserActOutput(lines);
+ }
+ const { diff } = result.successor;
+ const addedCount = diff.added.reduce((total, entry) => total + entry.count, 0);
+ const removedCount = diff.removed.reduce((total, entry) => total + entry.count, 0);
+ lines.push(`successor: ${result.successor.title} (${result.successor.url})`);
+ lines.push(`diff: ${diff.changed ? `+${addedCount} -${removedCount}` : "unchanged"}`);
+ if (diff.url) lines.push(` url: ${diff.url.before} -> ${diff.url.after}`);
+ if (diff.title) lines.push(` title: ${diff.title.before} -> ${diff.title.after}`);
+ const changes = [
+ ...diff.added.map((entry) => ` + ${entry.line}${entry.count === 1 ? "" : ` ×${entry.count}`}`),
+ ...diff.removed.map((entry) => ` - ${entry.line}${entry.count === 1 ? "" : ` ×${entry.count}`}`),
+ ];
+ let emittedChars = 0;
+ let emittedEntries = 0;
+ for (const change of changes) {
+ if (emittedEntries >= BROWSER_ACT_DIFF_ENTRY_LIMIT || emittedChars + change.length > BROWSER_ACT_DIFF_CHAR_LIMIT) break;
+ lines.push(change);
+ emittedEntries += 1;
+ emittedChars += change.length;
+ }
+ if (emittedEntries < changes.length) lines.push(` … ${changes.length - emittedEntries} more diff entries omitted`);
+ lines.push(result.successor.text);
+ return boundedBrowserActOutput(lines);
+}
+
+function boundedBrowserActOutput(lines: readonly string[]): string {
+ const output = lines.join("\n");
+ if (output.length <= BROWSER_ACT_RESULT_CHAR_LIMIT) return output;
+ return `${output.slice(0, BROWSER_ACT_RESULT_CHAR_LIMIT)}\n… browser_act output truncated at ${BROWSER_ACT_RESULT_CHAR_LIMIT} characters`;
+}
+
function formatPlaywrightResult(result: unknown): string {
return typeof result === "string" ? result : JSON.stringify(result);
}
diff --git a/packages/agent/src/translator/browser-act.ts b/packages/agent/src/translator/browser-act.ts
new file mode 100644
--- /dev/null
+++ b/packages/agent/src/translator/browser-act.ts
@@ -1,0 +1,358 @@
+import type { CuaActionBrowserAct, CuaActionBrowserSnapshot, CuaBrowserActStep, CuaBrowserExpectation } from "@onkernel/cua-ai";
+import { diffObservations, type BrowserObservation, type BrowserPresentation } from "./browser-observation";
+import type { BrowserExpectationEvaluation } from "./browser-wait";
+import type { BrowserActExpectationEvidence, BrowserActResult, BrowserActStepResult, BrowserWaitForResult } from "./types";
+
+const DEFAULT_ACT_TIMEOUT_MS = 30_000;
+type ActTimeoutReason = "global_timeout" | "step_timeout";
+type ActDeadline = { at: number; reason: ActTimeoutReason };
+
+class BrowserActDeadlineError extends Error {
+ constructor(readonly reason: ActTimeoutReason) {
+ super(reason === "global_timeout" ? "browser action plan timed out" : "browser action step timed out");
+ }
+}
+
+/**
+ * Narrow adapter between plan policy and browser mechanics. Implementations own live
+ * target/ref/CDP state; the orchestrator owns sequencing, deadlines, attribution, and
+ * stop decisions. `observe` is intentionally a full fenced AX observation: one baseline
+ * plus pre/post observations around steps make causal claims safer, but are not cheap.
+ */
+export interface BrowserActRuntime {
+ observe(tabId?: string): Promise<BrowserObservation>;
+ targetIds(): Promise<string[]>;
+ dialogCount(): number;
+ liveGeneration(frameId: string): number;
+ liveNavigationEpoch(targetId: string): number;
+ executeStep(step: CuaBrowserActStep, tabId?: string): Promise<void>;
+ wait(expect: CuaBrowserExpectation, baseline: BrowserObservation, targetId: string, tabId?: string, timeoutMs?: number, pollMs?: number): Promise<BrowserWaitForResult>;
+ evaluate(expect: CuaBrowserExpectation, observation: BrowserObservation, baseline: BrowserObservation): BrowserExpectationEvaluation;
+ present(observation: BrowserObservation, action: CuaActionBrowserSnapshot): BrowserPresentation;
+ render(presentation: BrowserPresentation): string;
+}
+
+/**
+ * Execute a dependent action plan and derive causal outcomes, stop reasons, and a stable
+ * successor. Expectations are evaluated against observations captured before input; a
+ * condition already matched before input is `preexisting`, never proof that input worked.
+ */
+export async function runBrowserAct(action: CuaActionBrowserAct, runtime: BrowserActRuntime): Promise<BrowserActResult> {
+ const finalStepIndex = action.steps.length - 1;
+ const globalDeadline: ActDeadline = { at: Date.now() + (action.timeout_ms ?? DEFAULT_ACT_TIMEOUT_MS), reason: "global_timeout" };
+ let baseline: BrowserObservation;
+ let current: BrowserObservation;
+ let targets: string[];
+ try {
+ baseline = current = await beforeDeadline(() => runtime.observe(action.tab_id), globalDeadline);
+ if (!isComplete(baseline)) throw new Error("baseline observation incomplete");
+ targets = await beforeDeadline(() => runtime.targetIds(), globalDeadline);
+ } catch (error) {
+ return unavailable(error, 0);
+ }
+ let dialogs = runtime.dialogCount();
+ const steps: BrowserActStepResult[] = [];
+ let stoppedAt: number | undefined;
+ let stopReason: BrowserActResult["stop_reason"];
+ let timedOut = false;
+
+ for (let index = 0; index < action.steps.length; index += 1) {
+ const step = action.steps[index]!;
+ const deadline = stepDeadline(step, globalDeadline);
+ let before: BrowserObservation;
+ let nextTargets: string[];
+ try {
+ before = await beforeDeadline(() => runtime.observe(action.tab_id), deadline);
+ nextTargets = await beforeDeadline(() => runtime.targetIds(), deadline);
+ } catch (error) {
+ const timeout = timeoutReason(error);
+ steps.push(stepResult(index, step, "unknown", [timeout ? message(error) : `pre-action observation failed: ${message(error)}`]));
+ timedOut ||= timeout !== undefined;
+ stoppedAt = index; stopReason = timeout ?? "control_flow"; break;
+ }
+ const preBoundary = boundary(current, before, targets, nextTargets, dialogs, runtime);
+ current = before; targets = nextTargets; dialogs = runtime.dialogCount();
+ if (!isComplete(before) || preBoundary) {
+ const reason = isComplete(before) ? `${preBoundary} detected before action` : "pre-action observation incomplete";
+ steps.push(stepResult(index, step, "unknown", [reason]));
+ stoppedAt = index; stopReason = preBoundary ?? "control_flow"; break;
+ }
+
+ const diagnostics: string[] = [];
+ let actionError: unknown;
+ let timeout: ActTimeoutReason | undefined;
+ try {
+ await beforeDeadline(() => runtime.executeStep(step, action.tab_id), deadline);
+ diagnostics.push("action dispatched");
+ } catch (error) {
+ actionError = error;
+ timeout = timeoutReason(error);
+ diagnostics.push(message(error));
+ }
+
+ let expectation: BrowserActExpectationEvidence | undefined;
+ let waitResult: BrowserWaitForResult | undefined;
+ let after: BrowserObservation | undefined;
+ let afterTargets: string[] | undefined;
+ if (!timeout) {
+ try {
+ if (step.expect) {
+ waitResult = await beforeDeadline(
+ () => runtime.wait(step.expect!, before, before.targetId, action.tab_id, remaining(deadline), action.poll_ms),
+ deadline,
+ );
+ expectation = expectationEvidence(waitResult);
+ if (waitResult.status === "timed_out" && expectation.status !== "failed") timeout = deadline.reason;
+ }
+ if (!timeout) {
+ after = await beforeDeadline(() => runtime.observe(action.tab_id), deadline);
+ afterTargets = await beforeDeadline(() => runtime.targetIds(), deadline);
+ }
+ } catch (error) {
+ timeout = timeoutReason(error);
+ diagnostics.push(timeout ? message(error) : `post-action observation failed: ${message(error)}`);
+ }
+ }
+
+ timedOut ||= timeout !== undefined;
+ const stale = isStale(actionError) || waitResult?.reason === "stale_ref" || expectation?.status === "unverifiable" && expectation.reason === "stale_ref";
+ const outcome = stepOutcome(expectation, actionError, stale);
+ if (expectation) diagnostics.push(`expectation ${expectation.status}`);
+ steps.push(stepResult(index, step, outcome, diagnostics, expectation));
+
+ const postBoundary = after && afterTargets ? boundary(before, after, targets, afterTargets, dialogs, runtime) : undefined;
+ if (after && afterTargets) { current = after; targets = afterTargets; dialogs = runtime.dialogCount(); }
+ stopReason = timeout
+ ?? (stale
+ ? "stale_ref"
+ : expectation?.status === "failed"
+ ? "expectation_failed"
+ : actionError
+ ? "action_failed"
+ : waitStopReason(waitResult)
+ ?? postBoundary
+ ?? (!after || !isComplete(after) || expectation?.status === "preexisting" || expectation?.status === "unverifiable" ? "control_flow" : undefined));
+ if (stopReason) { stoppedAt = index; break; }
+ }
+
+ let finalExpectation: BrowserActExpectationEvidence | undefined;
+ const terminalNavigation = stopReason === "navigation" && stoppedAt === finalStepIndex;
+ if (action.expect && (!stopReason || terminalNavigation)) {
+ try {
+ const result = await beforeDeadline(
+ () => runtime.wait(action.expect!, baseline, baseline.targetId, action.tab_id, remaining(globalDeadline), action.poll_ms),
+ globalDeadline,
+ );
+ finalExpectation = expectationEvidence(result);
+ timedOut ||= result.status === "timed_out";
+ if (result.status === "timed_out") { stopReason = "global_timeout"; stoppedAt = finalStepIndex; }
+ else if (finalExpectation.status === "failed") { stopReason = "expectation_failed"; stoppedAt = finalStepIndex; }
+ else if (finalExpectation.status === "unverifiable") { stopReason = waitStopReason(result) ?? "control_flow"; stoppedAt = finalStepIndex; }
+ } catch (error) {
+ const timeout = timeoutReason(error);
+ finalExpectation = unverifiableEvidence(runtime.evaluate(action.expect, baseline, baseline), message(error));
+ timedOut ||= timeout !== undefined;
+ stopReason = timeout ?? "control_flow"; stoppedAt = finalStepIndex;
+ }
+ }
+
+ let successor: BrowserActResult["successor"] | undefined;
+ let successorError: unknown;
+ if (stopReason === "global_timeout") {
+ successor = { status: "unavailable", error: "browser action plan timed out" };
+ }
+ for (let attempt = 0; attempt < 3 && !successor; attempt += 1) {
+ try {
+ const observed = await beforeDeadline(() => runtime.observe(action.tab_id), globalDeadline);
+ const successorTargets = await beforeDeadline(() => runtime.targetIds(), globalDeadline);
+ const lateBoundary = boundary(current, observed, targets, successorTargets, dialogs, runtime);
+ current = observed; targets = successorTargets; dialogs = runtime.dialogCount();
+ if (lateBoundary) {
+ stopReason ??= lateBoundary;
+ successorError = new Error(`${lateBoundary} changed successor observation`);
+ continue;
+ }
+ if (!isComplete(observed)) throw new Error("successor observation incomplete");
+ if (action.expect && finalExpectation && finalExpectation.status !== "failed") {
+ const evaluation = runtime.evaluate(action.expect, observed, baseline);
+ finalExpectation = evidenceFromEvaluation(
+ finalExpectation.before,
+ evaluation,
+ [...finalExpectation.diagnostics, ...evaluation.details.map((detail) => `successor: ${detail}`)],
+ );
+ if (evaluation.truth !== true) {
+ stopReason = evaluation.truth === false ? "expectation_failed" : "control_flow";
+ stoppedAt = finalStepIndex;
+ } else if (stopReason === "control_flow" && stoppedAt === finalStepIndex) {
+ stopReason = undefined;
+ stoppedAt = undefined;
+ }
+ }
+ const complete: CuaActionBrowserSnapshot = { type: "browser_snapshot", tab_id: action.tab_id, depth: Number.MAX_SAFE_INTEGER };
+ const presentation = runtime.present(observed, { type: "browser_snapshot", tab_id: action.tab_id, ...action.successor });
+ successor = {
+ status: "observed",
+ text: runtime.render(presentation),
+ url: observed.url,
+ title: observed.title,
+ diff: diffObservations(runtime.present(baseline, complete), runtime.present(observed, complete)),
+ };
+ } catch (error) {
+ successorError = error;
+ if (timeoutReason(error)) break;
+ }
+ }
+ if (!successor) successor = { status: "unavailable", error: message(successorError ?? new Error("successor observation unavailable")) };
+
+ return {
+ outcome: planOutcome(action, steps, finalExpectation, timedOut, stopReason),
+ steps,
+ ...(stoppedAt === undefined ? {} : { stopped_at: stoppedAt }),
+ ...(stopReason ? { stop_reason: stopReason } : {}),
+ ...(finalExpectation ? { final_expectation: finalExpectation } : {}),
+ successor,
+ };
+}
+
+/** A step works only when acknowledged input has newly established its postcondition. */
+function stepOutcome(expectation: BrowserActExpectationEvidence | undefined, actionError: unknown, stale: boolean): BrowserActStepResult["outcome"] {
+ if (expectation?.status === "failed" || stale) return "didnt";
+ if (expectation?.status === "newly_verified" && !actionError) return "worked";
+ return "unknown";
+}
+
+/**
+ * A plan works when its final condition was newly established, or—without a final
+ * condition—every step independently worked. Definitive failure wins; all uncertainty,
+ * preexisting evidence, missing expectations, timeouts, and unsafe stops remain unknown.
+ */
+function planOutcome(
+ action: CuaActionBrowserAct,
+ steps: readonly BrowserActStepResult[],
+ finalExpectation: BrowserActExpectationEvidence | undefined,
+ timedOut: boolean,
+ stopReason: BrowserActResult["stop_reason"],
+): BrowserActResult["outcome"] {
+ if (steps.some((step) => step.outcome === "didnt") || finalExpectation?.status === "failed") return "didnt";
+ if (timedOut) return "unknown";
+ const verified = action.expect
+ ? finalExpectation?.status === "newly_verified"
+ : steps.length === action.steps.length && steps.every((step) => step.outcome === "worked");
+ const verifiedNavigation = stopReason === "navigation" && steps.length === action.steps.length
+ && (steps.at(-1)?.outcome === "worked" || finalExpectation?.status === "newly_verified");
+ return verified && (!stopReason || verifiedNavigation) ? "worked" : "unknown";
+}
+
+function stepDeadline(step: CuaBrowserActStep, globalDeadline: ActDeadline): ActDeadline {
+ if (step.timeout_ms === undefined) return globalDeadline;
+ const at = Date.now() + step.timeout_ms;
+ return at < globalDeadline.at ? { at, reason: "step_timeout" } : globalDeadline;
+}
+
+function remaining(deadline: ActDeadline): number {
+ return Math.max(0, deadline.at - Date.now());
+}
+
+function beforeDeadline<T>(operation: () => Promise<T>, deadline: ActDeadline): Promise<T> {
+ const timeoutMs = remaining(deadline);
+ if (timeoutMs <= 0) return Promise.reject(new BrowserActDeadlineError(deadline.reason));
+ return new Promise<T>((resolve, reject) => {
+ const timer = setTimeout(() => reject(new BrowserActDeadlineError(deadline.reason)), timeoutMs);
+ void Promise.resolve()
+ .then(operation)
+ .then(
+ (value) => { clearTimeout(timer); resolve(value); },
+ (error: unknown) => { clearTimeout(timer); reject(error); },
+ );
+ });
+}
+
+function timeoutReason(error: unknown): ActTimeoutReason | undefined {
+ return error instanceof BrowserActDeadlineError ? error.reason : undefined;
+}
+
+function isComplete(observation: BrowserObservation): boolean {
+ return observation.incompleteFrames.length === 0;
+}
+
+function expectationEvidence(result: BrowserWaitForResult): BrowserActExpectationEvidence {
+ const before = expectationState(result.initial.truth);
+ const diagnostics = result.details;
+ if (result.evidence === "newly_verified" && before !== "matched" && result.final.truth === true) {
+ return { status: "newly_verified", before, after: "matched", diagnostics };
+ }
+ if (result.evidence === "preexisting" && before === "matched" && result.final.truth === true) {
+ return { status: "preexisting", before, after: "matched", diagnostics };
+ }
+ if (result.evidence === "failed" && result.final.truth === false) {
+ return { status: "failed", before, after: "not_matched", diagnostics };
+ }
+ return {
+ status: "unverifiable",
+ before,
+ after: "unknown",
+ diagnostics,
+ ...(result.reason ? { reason: result.reason } : {}),
+ };
+}
+
+function evidenceFromEvaluation(
+ before: BrowserActExpectationEvidence["before"],
+ evaluation: BrowserExpectationEvaluation,
+ diagnostics: string[],
+): BrowserActExpectationEvidence {
+ if (evaluation.truth === true) {
+ return before === "matched"
+ ? { status: "preexisting", before, after: "matched", diagnostics }
+ : { status: "newly_verified", before, after: "matched", diagnostics };
+ }
+ if (evaluation.truth === false) return { status: "failed", before, after: "not_matched", diagnostics };
+ return { status: "unverifiable", before, after: "unknown", diagnostics, ...(evaluation.reason ? { reason: evaluation.reason } : {}) };
+}
+
+function unverifiableEvidence(before: BrowserExpectationEvaluation, diagnostic: string): BrowserActExpectationEvidence {
+ return {
+ status: "unverifiable",
+ before: expectationState(before.truth),
+ after: "unknown",
+ diagnostics: [...before.details, diagnostic],
+ ...(before.reason ? { reason: before.reason } : {}),
+ };
+}
+
+function expectationState(truth: boolean | undefined): BrowserActExpectationEvidence["before"] {
+ return truth === true ? "matched" : truth === false ? "not_matched" : "unknown";
+}
+
+function boundary(before: BrowserObservation, after: BrowserObservation, oldTargets: readonly string[], newTargets: readonly string[], dialogs: number, runtime: BrowserActRuntime): BrowserActResult["stop_reason"] {
+ if (runtime.dialogCount() > dialogs) return "dialog";
+ if (oldTargets.length !== newTargets.length || oldTargets.some((id, index) => id !== newTargets[index])) return "control_flow";
+ if (before.targetId !== after.targetId || before.navigationEpoch !== after.navigationEpoch || runtime.liveNavigationEpoch(after.targetId) !== after.navigationEpoch) return "navigation";
+ if (before.generations.size !== after.generations.size) return "navigation";
+ for (const [frame, generation] of after.generations) {
+ if (runtime.liveGeneration(frame) !== generation || before.generations.get(frame) !== generation) return "navigation";
+ }
+ return undefined;
+}
+
+function waitStopReason(result?: BrowserWaitForResult): BrowserActResult["stop_reason"] {
+ if (!result?.reason) return undefined;
+ if (result.reason === "navigation" || result.reason === "dialog" || result.reason === "stale_ref") return result.reason;
+ return "control_flow";
+}
+
+function stepResult(index: number, step: CuaBrowserActStep, outcome: BrowserActStepResult["outcome"], diagnostics: string[], expectation?: BrowserActExpectationEvidence): BrowserActStepResult {
+ return { index, type: step.type, outcome, diagnostics, ...(expectation ? { expectation } : {}) };
+}
+
+function unavailable(error: unknown, stoppedAt: number): BrowserActResult {
+ return { outcome: "unknown", steps: [], stopped_at: stoppedAt, stop_reason: timeoutReason(error) ?? "control_flow", successor: { status: "unavailable", error: message(error) } };
+}
+
+function isStale(error: unknown): boolean {
+ return !!error && /(?:stale.*ref|ref.*stale)/i.test(message(error));
+}
+
+function message(error: unknown): string {
+ return error instanceof Error ? error.message : String(error);
+}
diff --git a/packages/agent/src/translator/browser-observation.ts b/packages/agent/src/translator/browser-observation.ts
--- a/packages/agent/src/translator/browser-observation.ts
+++ b/packages/agent/src/translator/browser-observation.ts
@@ -1,3 +1,5 @@
+import type { BrowserObservationDiff, BrowserObservationDiffEntry } from "./types";
+
/** Minimal CDP accessibility node used by browser observations. */
export interface AXNode {
readonly nodeId: string;
@@ -78,6 +80,31 @@
readonly shape: string;
}
+/** Compare complete presentations while normalizing away snapshot-scoped refs. */
+export function diffObservations(before: BrowserPresentation, after: BrowserPresentation): BrowserObservationDiff {
+ const beforeCounts = lineCounts(before);
+ const afterCounts = lineCounts(after);
+ const difference = (source: ReadonlyMap<string, number>, other: ReadonlyMap<string, number>): BrowserObservationDiffEntry[] =>
+ [...source].flatMap(([line, count]) => {
+ const delta = count - (other.get(line) ?? 0);
+ return delta > 0 ? [{ line, count: delta }] : [];
+ });
+ const added = difference(afterCounts, beforeCounts);
+ const removed = difference(beforeCounts, afterCounts);
+ const url = before.observation.url === after.observation.url ? undefined : { before: before.observation.url, after: after.observation.url };
+ const title = before.observation.title === after.observation.title ? undefined : { before: before.observation.title, after: after.observation.title };
+ return { changed: added.length > 0 || removed.length > 0 || !!url || !!title, added, removed, ...(url ? { url } : {}), ...(title ? { title } : {}) };
+}
+
+function lineCounts(presentation: BrowserPresentation): ReadonlyMap<string, number> {
+ const counts = new Map<string, number>();
+ for (const { text } of presentation.lines) {
+ const line = text.replace(/\u0000/g, "ref");
+ counts.set(line, (counts.get(line) ?? 0) + 1);
+ }
+ return counts;
+}
+
/** Signals that browser state changed while an observation was collected. */
export class ObservationChangedError extends Error {
constructor(message = "Browser observation changed during collection") {
diff --git a/packages/agent/src/translator/browser-ref-lifecycle.ts b/packages/agent/src/translator/browser-ref-lifecycle.ts
--- a/packages/agent/src/translator/browser-ref-lifecycle.ts
+++ b/packages/agent/src/translator/browser-ref-lifecycle.ts
@@ -193,6 +193,11 @@
this.deleteUnusedFrame(frame);
}
+ /** Current generation for an observation frame key, defaulting to zero before registration. */
+ currentGeneration(frameKey: string): number {
+ return this.frames.get(frameKey)?.generation ?? this.targets.get(frameKey)?.generation ?? 0;
+ }
+
isRefCurrent(entry: RefEntry): boolean {
if (entry.frameId === entry.targetId) return this.targets.get(entry.targetId)?.generation === entry.generation;
const frame = this.frames.get(entry.frameId);
diff --git a/packages/agent/src/translator/browser-wait.ts b/packages/agent/src/translator/browser-wait.ts
--- a/packages/agent/src/translator/browser-wait.ts
+++ b/packages/agent/src/translator/browser-wait.ts
@@ -17,8 +17,9 @@
observeTarget(targetId: string): Promise<BrowserObservation>;
dialogCount(): number;
targetExists(targetId: string): Promise<boolean>;
- /** Reserved for runtimes that expose generation checks outside observations. */
+ /** Optional lifecycle counters for runtimes that expose out-of-band stability checks. */
liveGeneration?(frameId: string): number;
+ liveNavigationEpoch?(targetId: string): number;
resolveRef: BrowserRefResolver;
now?(): number;
delay?(ms: number): Promise<void>;
@@ -30,6 +31,9 @@
timeoutMs?: number;
pollMs?: number;
tabId?: string;
+ /** Supply the pre-action state when verifying an action postcondition. */
+ baseline?: BrowserObservation;
+ targetId?: string;
}
function expectationNodes(observation: BrowserObservation): AXNode[] {
@@ -98,9 +102,9 @@
let targetId: string;
let baseline: BrowserObservation;
try {
- targetId = await beforeDeadline(() => runtime.selectTarget(options.tabId), remaining(), now);
+ targetId = options.targetId ?? await beforeDeadline(() => runtime.selectTarget(options.tabId), remaining(), now);
if (expired()) return timedOut(started, now());
- baseline = await runtime.observeTarget(targetId);
+ baseline = options.baseline ?? await runtime.observeTarget(targetId);
} catch (error) {
if (error instanceof WaitDeadlineError) return timedOut(started, now());
return failedObservation(started, now(), error);
@@ -109,12 +113,16 @@
if (initial.reason === "stale_ref" && !("any" in options.expect)) {
return terminal("interrupted", "unverifiable", initial, initial, started, now(), initial.reason);
}
+ if (options.baseline && baseline.incompleteFrames.length > 0) {
+ return terminal("unverifiable", "unverifiable", initial, initial, started, now(), "incomplete_observation");
+ }
if (expired()) return timedOut(started, now(), initial, initial);
- if (initial.truth === true) return terminal("satisfied", "preexisting", initial, initial, started, now());
+ if (initial.truth === true && !options.baseline) return terminal("satisfied", "preexisting", initial, initial, started, now());
const dialogs = runtime.dialogCount();
let final = initial;
while (!expired()) {
- await sleep(Math.min(poll, remaining()));
+ try { await beforeDeadline(() => sleep(Math.min(poll, remaining())), remaining(), now); }
+ catch (error) { if (error instanceof WaitDeadlineError) break; throw error; }
if (expired()) break;
let exists: boolean;
try { exists = await beforeDeadline(() => runtime.targetExists(targetId), remaining(), now); }
@@ -137,11 +145,11 @@
return terminal("interrupted", "unverifiable", initial, final, started, now(), final.reason);
}
if ((crossDocumentNavigation || sameDocumentNavigation) && locationExpectation) {
- if (final.truth === true && !expired()) return terminal("satisfied", "newly_verified", initial, final, started, now());
+ if (final.truth === true && !expired()) return terminal("satisfied", satisfiedEvidence(initial), initial, final, started, now());
continue;
}
if (expired()) break;
- if (final.truth === true) return terminal("satisfied", "newly_verified", initial, final, started, now());
+ if (final.truth === true) return terminal("satisfied", satisfiedEvidence(initial), initial, final, started, now());
if (observation.incompleteFrames.length > 0) {
final = { ...final, truth: undefined, reason: final.reason ?? "incomplete_observation" };
continue;
@@ -166,6 +174,10 @@
}
}
+function satisfiedEvidence(initial: BrowserExpectationEvidence): BrowserWaitForResult["evidence"] {
+ return initial.truth === true ? "preexisting" : "newly_verified";
+}
+
function containsLocationExpectation(expectation: CuaBrowserExpectation): boolean {
if ("all" in expectation) return expectation.all.some(containsLocationExpectation);
if ("any" in expectation) return expectation.any.some(containsLocationExpectation);
diff --git a/packages/agent/src/translator/browser.ts b/packages/agent/src/translator/browser.ts
--- a/packages/agent/src/translator/browser.ts
+++ b/packages/agent/src/translator/browser.ts
@@ -1,5 +1,6 @@
import {
normalizeGotoUrl,
+ type CuaActionBrowserAct,
type CuaActionBrowserClick,
type CuaActionBrowserDrag,
type CuaActionBrowserFill,
@@ -12,6 +13,7 @@
type CuaActionBrowserSnapshot,
type CuaActionBrowserWaitFor,
type CuaBrowserAction,
+ type CuaBrowserActStep,
type CuaBrowserExpectation,
} from "@onkernel/cua-ai";
import { CdpConnection, type CdpEventMessage } from "./cdp";
@@ -40,6 +42,7 @@
type ObservationLine,
type RenderContext,
} from "./browser-observation";
+import { runBrowserAct } from "./browser-act";
import {
REF_STATE_VERSION,
RefGenerationLifecycle,
@@ -48,8 +51,8 @@
type GenerationCapture,
type RefEntry,
} from "./browser-ref-lifecycle";
-import { waitForBrowserExpectation, type BrowserExpectationEvaluation } from "./browser-wait";
-import type { BatchReadResult, BrowserWaitForResult } from "./types";
+import { evaluateBrowserExpectation, waitForBrowserExpectation, type BrowserExpectationEvaluation } from "./browser-wait";
+import type { BatchReadResult, BrowserActResult, BrowserWaitForResult } from "./types";
const SNAPSHOT_CHAR_LIMIT = 50_000;
const DEFAULT_SNAPSHOT_DEPTH = 15;
@@ -74,6 +77,15 @@
/**
* Executes browser-plane canonical actions over CDP.
*
+ * Ownership boundary: this class owns connection-coupled mutable state and primitive
+ * browser mechanics—CDP sessions/targets, ref resolution, document generations,
+ * observation collection/rendering, and individual input operations. Multi-operation
+ * policy belongs outside this class behind narrow runtime interfaces: semantic polling
+ * lives in `browser-wait.ts`, and dependent plan control flow lives in `browser-act.ts`.
+ * A future feature should be added here only when it must directly coordinate the live
+ * CDP/ref state; orchestration expressible as observe/evaluate/execute primitives should
+ * be a separate module adapted by this executor.
+ *
* Element refs are snapshot-scoped: each snapshot/find mints `e<N>` ids
* mapped to CDP backend node ids for the target's current generation. Any
* main-frame navigation — our own navigate() or a page-initiated one seen
@@ -282,6 +294,8 @@
switch (action.type) {
case "browser_snapshot":
return [{ type: "browser_text", label: "snapshot", text: await this.snapshot(action) }];
+ case "browser_act":
+ return [{ type: "browser_act", result: await this.act(action) }];
case "browser_wait_for":
return [{ type: "browser_wait_for", result: await this.waitFor(action) }];
case "browser_text":
@@ -355,18 +369,50 @@
}
private waitFor(action: CuaActionBrowserWaitFor): Promise<BrowserWaitForResult> {
- return waitForBrowserExpectation(
- {
- selectTarget: (tabId) => this.resolveTarget(tabId),
- observeTarget: (targetId) => this.observe(targetId),
- dialogCount: () => this.dialogNotes.length,
- targetExists: async (targetId) => (await this.cdp.pageTargets()).some((target) => target.targetId === targetId),
- resolveRef: (expectation, observation) => this.evaluateRefExpectation(expectation, observation),
- },
- { expect: action.expect, timeoutMs: action.timeout_ms, pollMs: action.poll_ms, tabId: action.tab_id },
- );
+ return this.waitForExpectation(action.expect, { timeoutMs: action.timeout_ms, pollMs: action.poll_ms, tabId: action.tab_id });
}
+ private waitForExpectation(expect: CuaBrowserExpectation, options: { timeoutMs?: number; pollMs?: number; tabId?: string; baseline?: BrowserObservation; targetId?: string }): Promise<BrowserWaitForResult> {
+ return waitForBrowserExpectation({
+ selectTarget: (tabId) => this.resolveTarget(tabId),
+ observeTarget: (targetId) => this.observe(targetId, false),
+ dialogCount: () => this.dialogNotes.length,
+ targetExists: async (targetId) => (await this.cdp.pageTargets()).some((target) => target.targetId === targetId),
+ resolveRef: (expectation, observation) => this.evaluateRefExpectation(expectation, observation),
+ }, { expect, ...options });
+ }
+
+ private act(action: CuaActionBrowserAct): Promise<BrowserActResult> {
+ return runBrowserAct(action, {
+ observe: (tabId) => this.observe(tabId, false),
+ targetIds: async () => (await this.cdp.pageTargets()).map((target) => target.targetId).sort(),
+ dialogCount: () => this.dialogNotes.length,
+ liveGeneration: (frameId) => this.lifecycle.currentGeneration(frameId),
+ liveNavigationEpoch: (targetId) => this.navigationEpochs.get(targetId) ?? 0,
+ executeStep: (step, tabId) => this.executeActStep(step, tabId),
+ wait: (condition, baseline, targetId, tabId, timeoutMs, pollMs) => this.waitForExpectation(condition, { baseline, targetId, tabId, timeoutMs, pollMs }),
+ evaluate: (condition, observation, baseline) => evaluateBrowserExpectation(condition, observation, baseline, (ref, state) => this.evaluateRefExpectation(ref, state)),
+ present: (observation, snapshot) => this.presentObservation(observation, snapshot),
+ render: (presentation) => this.renderObservation(presentation, false),
+ });
+ }
+
+ private async executeActStep(step: CuaBrowserActStep, tabId?: string): Promise<void> {
+ switch (step.type) {
+ case "click": return this.click({ type: "browser_click", ref: step.ref, button: step.button, num_clicks: step.num_clicks, modifiers: step.modifiers, tab_id: tabId });
+ case "hover": return this.hover({ type: "browser_hover", ref: step.ref, tab_id: tabId });
+ case "fill": return this.fill({ type: "browser_fill", ref: step.ref, value: step.value, tab_id: tabId });
+ case "scroll_to": return this.scrollTo({ type: "browser_scroll_to", ref: step.ref, tab_id: tabId });
+ case "key": return this.key({ type: "browser_key", text: step.text, repeat: step.repeat, tab_id: tabId });
+ case "type": {
+ const session = await this.session(tabId);
+ await this.cdp.send("Input.insertText", { text: step.text }, session);
+ return;
+ }
+ case "wait": await new Promise((resolve) => setTimeout(resolve, step.ms ?? 0)); return;
+ }
+ }
+
private evaluateRefExpectation(
expectation: Extract<CuaBrowserExpectation, { type: "ref" }>,
observation: BrowserObservation,
@@ -547,11 +593,11 @@
};
}
- private renderObservation(presentation: BrowserPresentation): string {
+ private renderObservation(presentation: BrowserPresentation, comparePrevious = true): string {
const { observation, cacheKey, lines, shape } = presentation;
const cached = this.lastSnapshots.get(observation.targetId);
this.lastSnapshots.set(observation.targetId, { key: cacheKey, shape });
- if (cached?.key === cacheKey && cached.shape === shape) return UNCHANGED_SNAPSHOT;
+ if (comparePrevious && cached?.key === cacheKey && cached.shape === shape) return UNCHANGED_SNAPSHOT;
let text = "";
for (const line of lines) {
if (text.length > SNAPSHOT_CHAR_LIMIT) break;
@@ -737,6 +783,7 @@
const modifiers = modifierBits(action.modifiers);
const button = action.button ?? "left";
const clicks = action.num_clicks ?? 1;
+ if (!Number.isInteger(clicks) || clicks < 1 || clicks > 3) throw new Error("num_clicks must be an integer between 1 and 3");
await this.cdp.send("Input.dispatchMouseEvent", { type: "mouseMoved", x: point.x, y: point.y, modifiers }, point.session);
// Native multi-clicks are separate press/release cycles with an
// incrementing clickCount; a single pair with the final count is not how
diff --git a/packages/agent/src/translator/translator.ts b/packages/agent/src/translator/translator.ts
--- a/packages/agent/src/translator/translator.ts
+++ b/packages/agent/src/translator/translator.ts
@@ -137,8 +137,12 @@
await flush();
const reads = await this.browser().execute(action);
result.readResults.push(...reads);
- const failedWait = reads.some((read) => read.type === "browser_wait_for" && read.result.status !== "satisfied");
- if (failedWait) {
+ const stopped = reads.some((read) =>
+ read.type === "browser_wait_for"
+ ? read.result.status !== "satisfied"
+ : read.type === "browser_act" && read.result.stop_reason !== undefined && read.result.outcome !== "worked",
+ );
+ if (stopped) {
const skippedActions = actions.length - index - 1;
... diff truncated: showing 800 of 1911 linesYou can send follow-ups to the cloud agent here.
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summary
actin browser mode (browser_actin hybrid mode) for dependent browser action plans of up to 20 stepsworked,didnt, orunknownoutcomes with documented stop reasons and typed before/after expectation evidencebehavior
browser_actis for dependent sequences where later input is only safe if earlier input produced the expected state. A step's optionaltimeout_mscovers performing that step and verifying its expectation. The parenttimeout_mscovers the complete sequence plus its final expectation; step deadlines are capped by the remaining global deadline. Verification reuses the semantic wait engine added in #64.The action plan does not claim success merely because input was dispatched. A step is
workedonly when its postcondition is newly verified; preexisting conditions and uncertain delivery remainunknown. Expectation evidence is a discriminated union of validbefore/afterstates, while human-readable diagnostics are explicitly non-control-flow data.BrowserExecutorremains the adapter for connection-coupled CDP/ref mechanics. Sequencing, deadline, attribution, and stop policy live inbrowser-act.tsbehind the narrowBrowserActRuntimeinterface; this ownership boundary is documented on both abstractions.base
main(includes #63 observation/ref lifecycle hardening and #64 semantic waits)size
1,394 changed lines: 1,348 additions, 46 deletions.
testing
npm run typechecknpm test --workspace @onkernel/cua-ai— 182 passednpm test --workspace @onkernel/cua-agent— 325 passed, 19 skipped live testsnpm test --workspace @onkernel/cua-cli— 94 passedgit diff --check origin/main...HEADNote
Medium Risk
Large new CDP orchestration path affects batch semantics and model-facing browser tools; behavior is heavily tested but touches ref lifecycle, timeouts, and navigation boundaries.
Overview
Adds
browser_act(exposed asactin browser mode andbrowser_actin hybrid): a dependent multi-step browser plan with optional per-step and plan-level semantic expectations, layered deadlines, and honestworked/didnt/unknownoutcomes plus stop reasons.New
browser-act.tsorchestration sits behind a narrow runtime adapter onBrowserExecutor; semantic waits gain baseline/target hooks for post-action verification. Results include a stable successor AX snapshot, normalized observation diff, and bounded model-facing formatting. Mixed canonical batches now short-circuit when a plan hits a control-flow boundary (not only failedwait_for).Also adds a draft
docs/agent-tool-configuration-spec.mddescribing a future explicittools[]API (referencesbrowser_act; no runtime change there).num_clicksis tightened to integers 1–3 in schemas and CDP click dispatch.Reviewed by Cursor Bugbot for commit 8f7b9b2. Bugbot is set up for automated code reviews on this repo. Configure here.