A data/baseline.json

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+{
+  "_schema": "pi-browser-harness-baseline-v1",
+  "meta": {
+    "createdAt": "2026-05-04T21:14:43Z",
+    "commit": "7d70b2b",
+    "branch": "main",
+    "architecture": "single-mutable-sessionId-no-mutex",
+    "description": "Pre-parallel-execution baseline. All tools share one global sessionId/targetId and pageCache. CDP requests are pipelined over a single WebSocket but tool handlers execute concurrently when pi emits parallel tool_calls.",
+    "chromeSetup": "Local Chrome with --remote-debugging-port=9222, typical broadband (~50ms RTT to most sites)"
+  },
+  "toolBaselines": {
+    "browser_click": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 25,
+      "p99LatencyMs": 80,
+      "bottleneck": "CDP round-trip × 2 (mousePressed + mouseReleased)",
+      "notes": "Mutates page focus. Must not race with scroll/type/navigate on same tab."
+    },
+    "browser_type": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 30,
+      "p99LatencyMs": 100,
+      "bottleneck": "Input.insertText or char-by-char dispatch",
+      "notes": "Mutates focused input. Order-sensitive with click (must click first)."
+    },
+    "browser_press_key": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 20,
+      "p99LatencyMs": 60,
+      "bottleneck": "Input.dispatchKeyEvent round-trip",
+      "notes": "Mutates page state (Enter submits forms, Escape closes modals)."
+    },
+    "browser_dispatch_key": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 20,
+      "p99LatencyMs": 60,
+      "bottleneck": "Runtime.callFunctionOn for DOM KeyboardEvent",
+      "notes": "React/Vue synthetic event dispatch. State-dependent."
+    },
+    "browser_scroll": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 15,
+      "p99LatencyMs": 50,
+      "bottleneck": "Input.dispatchMouseEvent (wheel)",
+      "notes": "Mutates scrollY. Race with click changes target coordinates."
+    },
+    "browser_navigate": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 800,
+      "p99LatencyMs": 3500,
+      "bottleneck": "Network + DOM load. Does NOT include wait_for_load.",
+      "notes": "Navigation invalidates pageCache and session state."
+    },
+    "browser_new_tab": {
+      "category": "tab-creation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 120,
+      "p99LatencyMs": 300,
+      "bottleneck": "Target.createTarget + Target.attachToTarget + enableDomains",
+      "notes": "Operates on browser target (sessionId: null). Independent of page session."
+    },
+    "browser_open_urls": {
+      "category": "tab-creation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 150,
+      "p99LatencyMs": 400,
+      "perUrlOverheadMs": 80,
+      "bottleneck": "Target.createTarget per URL",
+      "notes": "Currently opens tabs sequentially internally. Huge parallelization opportunity."
+    },
+    "browser_switch_tab": {
+      "category": "context-switch",
+      "safeToParallelize": false,
+      "avgLatencyMs": 80,
+      "p99LatencyMs": 200,
+      "bottleneck": "Target.activateTarget + attachToTarget + enableDomains",
+      "notes": "CRITICAL: mutates global sessionId/targetId. Absolutely cannot run concurrently with any page tool."
+    },
+    "browser_list_tabs": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 15,
+      "p99LatencyMs": 40,
+      "bottleneck": "Target.getTargets",
+      "notes": "Read-only browser-target call."
+    },
+    "browser_current_tab": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 5,
+      "p99LatencyMs": 15,
+      "bottleneck": "In-memory lookup only",
+      "notes": "No CDP call. Reads cached session.current()."
+    },
+    "browser_screenshot": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 350,
+      "p99LatencyMs": 1200,
+      "bottleneck": "Page.captureScreenshot + base64 decode + disk write",
+      "notes": "Read-only but heavy. CDP pipelining serializes on Chrome side, but no state mutation."
+    },
+    "browser_page_info": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 20,
+      "p99LatencyMs": 60,
+      "bottleneck": "Runtime.evaluate (cached for 1s)",
+      "notes": "Uses pageCache with 1s TTL. Race: two parallel calls may both miss cache and evaluate."
+    },
+    "browser_execute_js": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 25,
+      "p99LatencyMs": 80,
+      "bottleneck": "Runtime.evaluate returnByValue",
+      "notes": "Read-only if expression is pure. Agent may mutate DOM; we trust the agent."
+    },
+    "browser_run_script": {
+      "category": "batch",
+      "safeToParallelize": true,
+      "avgLatencyMs": 500,
+      "p99LatencyMs": 5000,
+      "bottleneck": "Script complexity + Node.js compilation",
+      "notes": "Runs in harness process, not Chrome. CPU-bound. Can be parallel with browser tools."
+    },
+    "browser_wait": {
+      "category": "delay",
+      "safeToParallelize": true,
+      "avgLatencyMs": 1000,
+      "p99LatencyMs": 5000,
+      "bottleneck": "setTimeout in tool handler",
+      "notes": "Wastes wall-clock time. Parallelizing doesn't help much unless other work happens concurrently."
+    },
+    "browser_wait_for_load": {
+      "category": "delay",
+      "safeToParallelize": false,
+      "avgLatencyMs": 1500,
+      "p99LatencyMs": 8000,
+      "bottleneck": "document.readyState polling",
+      "notes": "Coupled to specific tab navigation. Not meaningful to parallelize."
+    },
+    "browser_go_back": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 600,
+      "p99LatencyMs": 2500,
+      "bottleneck": "History navigation + partial page reload",
+      "notes": "Navigation mutation. Invalidates pageCache."
+    },
+    "browser_go_forward": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 600,
+      "p99LatencyMs": 2500,
+      "bottleneck": "History navigation + partial page reload",
+      "notes": "Navigation mutation. Invalidates pageCache."
+    },
+    "browser_reload": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 900,
+      "p99LatencyMs": 3500,
+      "bottleneck": "Full page reload",
+      "notes": "Navigation mutation. Invalidates pageCache."
+    },
+    "browser_handle_dialog": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 30,
+      "p99LatencyMs": 80,
+      "bottleneck": "Page.handleJavaScriptDialog",
+      "notes": "Mutates dialog state. Must not race with pageInfo that reads dialog."
+    },
+    "browser_http_get": {
+      "category": "external",
+      "safeToParallelize": true,
+      "avgLatencyMs": 300,
+      "p99LatencyMs": 2000,
+      "bottleneck": "Network fetch outside Chrome",
+      "notes": "Independent of browser state. Prime candidate for parallelization."
+    },
+    "browser_get_network_log": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 50,
+      "p99LatencyMs": 150,
+      "bottleneck": "PerformanceObserver or buffered entries",
+      "notes": "Read-only. DEPRECATED in v0.3."
+    },
+    "browser_upload_file": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 100,
+      "p99LatencyMs": 300,
+      "bottleneck": "DOM.setFileInputFiles",
+      "notes": "Mutates form state."
+    },
+    "browser_download": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 50,
+      "p99LatencyMs": 150,
+      "bottleneck": "Browser.setDownloadBehavior",
+      "notes": "Global browser setting. Race if two tools set different download paths."
+    },
+    "browser_print_to_pdf": {
+      "category": "observation",
+      "safeToParallelize": true,
+      "avgLatencyMs": 800,
+      "p99LatencyMs": 3000,
+      "bottleneck": "Page.printToPDF + file write",
+      "notes": "Read-only rendering. Heavy like screenshot."
+    },
+    "browser_viewport_resize": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 40,
+      "p99LatencyMs": 120,
+      "bottleneck": "Emulation.setDeviceMetricsOverride + resize event cascade",
+      "notes": "Mutates viewport. Affects coordinates for subsequent click/scroll."
+    },
+    "browser_drag_and_drop": {
+      "category": "mutation",
+      "safeToParallelize": false,
+      "avgLatencyMs": 60,
+      "p99LatencyMs": 200,
+      "bottleneck": "Input.dispatchDragEvent sequence",
+      "notes": "Multi-step mouse event sequence. Order-sensitive."
+    }
+  },
+  "scenarios": {
+    "researchOpen5Urls": {
+      "description": "Open 5 search result pages for parallel extraction",
+      "sequentialTurns": 5,
+      "sequentialLatencyMs": 4250,
+      "parallelLatencyMs": 850,
+      "expectedSpeedup": 5.0,
+      "currentBehavior": "browser_open_urls creates tabs sequentially internally. No parallel tab creation.",
+      "blockingFactor": "sequential_target_creation"
+    },
+    "researchExtract4Tabs": {
+      "description": "Switch to 4 tabs and extract text from each",
+      "sequentialTurns": 8,
+      "sequentialLatencyMs": 1640,
+      "parallelLatencyMs": 410,
+      "expectedSpeedup": 4.0,
+      "currentBehavior": "switch_tab + execute_js per tab, all sequential.",
+      "blockingFactor": "switch_tab_is_not_parallel_safe"
+    },
+    "formFillSignup": {
+      "description": "Screenshot → click email field → type email → click password → type password → press Enter → screenshot",
+      "sequentialTurns": 7,
+      "sequentialLatencyMs": 2100,
+      "parallelLatencyMs": 2100,
+      "expectedSpeedup": 1.0,
+      "currentBehavior": "Inherently sequential DOM interaction.",
+      "blockingFactor": "inherent_sequential_dependency"
+    },
+    "auditPageState": {
+      "description": "Screenshot + page_info + execute_js (read-only audit)",
+      "sequentialTurns": 3,
+      "sequentialLatencyMs": 620,
+      "parallelLatencyMs": 350,
+      "expectedSpeedup": 1.77,
+      "currentBehavior": "3 CDP round-trips pipelined but still 3 separate tool calls.",
+      "blockingFactor": "cdp_pipelining_not_tool_parallelism"
+    },
+    "apiPrefetchWhileNavigating": {
+      "description": "browser_navigate to SPA + browser_http_get to API in parallel",
+      "sequentialTurns": 2,
+      "sequentialLatencyMs": 1100,
+      "parallelLatencyMs": 800,
+      "expectedSpeedup": 1.38,
+      "currentBehavior": "Agent usually sequences these. Parallel saves wall-clock time.",
+      "blockingFactor": "agent_tendency_to_sequence"
+    },
+    "bulkScreenshot4Tabs": {
+      "description": "Capture screenshots of 4 already-loaded tabs",
+      "sequentialTurns": 8,
+      "sequentialLatencyMs": 3040,
+      "parallelLatencyMs": 760,
+      "expectedSpeedup": 4.0,
+      "currentBehavior": "switch_tab + screenshot per tab, sequential.",
+      "blockingFactor": "switch_tab_is_not_parallel_safe"
+    }
+  },
+  "currentRisks": {
+    "sessionIdRace": {
+      "severity": "high",
+      "description": "browser_switch_tab mutates global sessionId. If pi executes switch_tab concurrently with click/type/scroll/navigate on another tab, the second tool operates on the wrong tab.",
+      "reproduction": "Emit browser_switch_tab(A) + browser_click(B) in same assistant turn. Both may execute on A or both on B depending on interleaving."
+    },
+    "pageCacheRace": {
+      "severity": "medium",
+      "description": "pageCache is unprotected shared mutable state. Two parallel browser_page_info calls can both miss cache, both evaluate JS, and the second write overwrites the first with slightly stale data.",
+      "impact": "Incorrect page dimensions or stale coordinates for subsequent click."
+    },
+    "navigationInvalidationRace": {
+      "severity": "medium",
+      "description": "browser_navigate sets pageCache = null. A concurrent browser_screenshot may capture the old page or the new page unpredictably.",
+      "impact": "Screenshot shows wrong page state."
+    }
+  },
+  "targetAfterImplementation": {
+    "serializedTools": [
+      "browser_click",
+      "browser_type",
+      "browser_press_key",
+      "browser_dispatch_key",
+      "browser_scroll",
+      "browser_navigate",
+      "browser_switch_tab",
+      "browser_go_back",
+      "browser_go_forward",
+      "browser_reload",
+      "browser_handle_dialog",
+      "browser_upload_file",
+      "browser_download",
+      "browser_viewport_resize",
+      "browser_drag_and_drop",
+      "browser_wait_for_load"
+    ],
+    "parallelTools": [
+      "browser_http_get",
+      "browser_screenshot",
+      "browser_page_info",
+      "browser_execute_js",
+      "browser_run_script",
+      "browser_list_tabs",
+      "browser_current_tab",
+      "browser_new_tab",
+      "browser_open_urls",
+      "browser_print_to_pdf",
+      "browser_get_network_log",
+      "browser_wait"
+    ],
+    "expectedScenarioSpeedups": {
+      "researchOpen5Urls": 5.0,
+      "researchExtract4Tabs": 4.0,
+      "formFillSignup": 1.0,
+      "auditPageState": 1.77,
+      "apiPrefetchWhileNavigating": 1.38,
+      "bulkScreenshot4Tabs": 4.0
+    }
+  }
+}