[eric] browser: OSW_BROWSER_NO_LEVERS bench flag to A/B the speed levers on/off

backend/apps/agents/browser/browser_agent.py

@@ -63,6 +63,7 @@ from backend.apps.agents.browser import browser_wait
 from backend.apps.agents.browser import browser_schema
 from backend.apps.agents.browser.browser_schema import (
     _ACTION_TOOLS_REQUIRING_REPORT,
+    _LEVERS_ON,
     ACTION_MAP,
     BROWSER_TOOLS_SCHEMA,
     MAX_TURNS,
@@ -802,7 +803,7 @@ async def run_browser_agent(
     # wording), but a similar verified route may exist; hand it to the model as
     # advisory text so it follows a known path instead of re-exploring.
     route_hint_keys: list[tuple] = []
-    if not replay_prefix_note:
+    if _LEVERS_ON and not replay_prefix_note:
         _h_skill, _h_score = browser_skills.find_similar_skill(replay_host, skill_key_task)
         if _h_skill:
             _hint, route_hint_keys = browser_skills.render_route_hint(_h_skill, skill_key_task, _h_score)
@@ -816,7 +817,7 @@ async def run_browser_agent(
     # Pre-nav landed on a results page (the cold entry case): scan it NOW so the
     # model's very first turn can pick a candidate instead of read-then-decide.
     _start_url = (current_url or initial_url or "").split("#")[0]
-    if _start_url and _RESULTS_URL_RE.search(_start_url):
+    if _LEVERS_ON and _start_url and _RESULTS_URL_RE.search(_start_url):
         auto_scanned_urls.add(_start_url)
         _scan_json, _sc_ms = await _scan_results(task)
         if _scan_json:
@@ -1442,7 +1443,7 @@ async def run_browser_agent(
                 # per URL, only on the tight throwaway-dismiss vocabulary that
                 # never sits on a task-needed control, so it can't close anything
                 # required. After closing, re-list so the model sees the page beneath.
-                if tu.name in _AUTO_STATE_TOOLS and "error" not in result:
+                if _LEVERS_ON and tu.name in _AUTO_STATE_TOOLS and "error" not in result:
                     _pop_url = (result.get("url") or last_seen_url or "").split("#")[0]
                     if _pop_url and _pop_url not in dismissed_popup_urls:
                         _close = interstitial_dismiss_target("\n".join(attached_state_seen))
@@ -1464,7 +1465,7 @@ async def run_browser_agent(
                 # costs a read-then-decide turn pair; the cheap aux model reads it
                 # now so the pick happens on this same turn. Capped, per-URL,
                 # fail-silent (a miss just means the old two-turn dance).
-                if (tu.name in _AUTO_STATE_TOOLS and "error" not in result
+                if (_LEVERS_ON and tu.name in _AUTO_STATE_TOOLS and "error" not in result
                         and auto_scan_count < _AUTO_SCAN_MAX_PER_RUN):
                     _scan_url = (result.get("url") or last_seen_url or "").split("#")[0]
                     if _scan_url and _scan_url not in auto_scanned_urls and _RESULTS_URL_RE.search(_scan_url):
@@ -1513,7 +1514,7 @@ async def run_browser_agent(
                         if replay_prefix_note:
                             result["text"] = f"{result.get('text') or ''}{replay_prefix_note}"
                             replay_prefix_note = ""
-                        elif not route_hint_keys:
+                        elif _LEVERS_ON and not route_hint_keys:
                             _h_skill, _h_score = browser_skills.find_similar_skill(cur_host, skill_key_task)
                             if _h_skill:
                                 _hint, route_hint_keys = browser_skills.render_route_hint(_h_skill, skill_key_task, _h_score)

backend/apps/agents/browser/browser_schema.py

@@ -6,6 +6,30 @@ prompt, and the turn/report invariants. Exceeds the 300-LOC soft ceiling on
 purpose because it is one cohesive data blob, not multiple responsibilities.
 """
 
+import os
+
+# Bench-only A/B switch: OSW_BROWSER_NO_LEVERS=1 reverts the prompt to its
+# pre-speed-lever behavior (narration allowed beside actions, no merge-verify
+# shortcut) so a controlled run can measure whether the levers move the needle.
+# Default (unset) = levers ON, the shipped behavior.
+_LEVERS_ON = os.environ.get("OSW_BROWSER_NO_LEVERS", "") not in ("1", "true", "TRUE")
+
+_THINK_SHORTER = (
+    "Do NOT also write a free-text sentence next to your action tools: your ReportProgress "
+    "fields ARE your thinking, and a separate prose explanation just repeats them and slows "
+    "the turn (it is shown to the user twice). The ONLY time to write a plain message is your "
+    "FINAL turn, when the task is done and you call no action tool: that message is your "
+    "answer to the user (the OUTCOME line). Every other turn: ReportProgress + tools, no prose.\n"
+) if _LEVERS_ON else ""
+
+_MERGE_VERIFY = (
+    "When that `expect` CONFIRMS (the result says 'Confirmed: ...'), that IS your "
+    "verification: go STRAIGHT to your final OUTCOME line and cite it. Do NOT spend an "
+    "extra screenshot or read turn to re-check what the confirmation already proved, that "
+    "is a wasted round-trip. Only take a separate verification step when `expect` came "
+    "back 'NOT confirmed' or you forgot to pass one.\n"
+) if _LEVERS_ON else ""
+
 MODEL_MAP = {
     "sonnet": "claude-sonnet-4-6",
     "opus": "claude-opus-4-6",
@@ -621,11 +645,7 @@ SYSTEM_PROMPT = (
     "needs (the exact selector, index, or value). Each token you write is generated one at a "
     "time and is the main thing that slows a turn, so write the fewest that still carry the "
     "plan forward. Only write working_memory when you learn something NEW this turn; else 'none'.\n"
-    "Do NOT also write a free-text sentence next to your action tools: your ReportProgress "
-    "fields ARE your thinking, and a separate prose explanation just repeats them and slows "
-    "the turn (it is shown to the user twice). The ONLY time to write a plain message is your "
-    "FINAL turn, when the task is done and you call no action tool: that message is your "
-    "answer to the user (the OUTCOME line). Every other turn: ReportProgress + tools, no prose.\n"
+    + _THINK_SHORTER +
     "Emit ReportProgress and your action tool(s) together in the same response. "
     "If you skip ReportProgress, your action tools will be REJECTED with an error "
     "and you will have to retry. This is not optional. Read-only tools "
@@ -642,11 +662,7 @@ SYSTEM_PROMPT = (
     "last one in the thread), pass `expect` set to proof it landed, and NEVER fire it a "
     "second time unless you have verified the first did NOT go through. This is how you "
     "avoid both ghost-successes and double-sends.\n"
-    "When that `expect` CONFIRMS (the result says 'Confirmed: ...'), that IS your "
-    "verification: go STRAIGHT to your final OUTCOME line and cite it. Do NOT spend an "
-    "extra screenshot or read turn to re-check what the confirmation already proved, that "
-    "is a wasted round-trip. Only take a separate verification step when `expect` came "
-    "back 'NOT confirmed' or you forgot to pass one.\n\n"
+    + _MERGE_VERIFY + "\n"
 
     "## Loop awareness\n"
     "If you see a tool result containing 'LOOP DETECTED' or '⚠️', it means you "