[week-02] 26512076

submissions/26512076/week-02/REPORT.md

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+\# Week 02 — Harness A/B Report
+
+
+
+\## 1. Variant definition
+
+
+
+이번 실험에서는 모델, 태스크, 도구를 동일하게 유지하고 하네스만 변경했다. Provider는 OpenRouter, 모델은 `openrouter/free`를 사용했다. 공통 도구는 `read\_file(path)`와 `count\_pattern(path, pattern)`이다. 태스크는 `app.log`에서 ERROR가 가장 많이 발생한 시간대를 찾는 것이며, 정답 문자열이 최종 답변에 포함되면 성공으로 판정했다.
+
+
+
+ReAct 하네스는 매 단계에서 Thought → Action → Observation을 반복하며 전체 대화 기록을 다음 호출에 전달한다. 모델이 답변을 완료하거나 최대 8단계에 도달하면 종료한다. 도구 오류도 Observation으로 돌려주므로 다음 단계에서 행동을 수정할 수 있다.
+
+
+
+Plan-then-Execute 하네스는 먼저 전체 계획을 JSON 리스트로 생성한 다음 각 단계를 순서대로 실행한다. 한 단계당 도구 호출은 최대 3라운드이며, 계획에서 벗어났을 때 재계획은 최대 1회 허용된다. 따라서 두 하네스는 주로 컨텍스트 관리, 종료 조건, 오류 복구 축에서 다르다. 도구 granularity는 동일하며, 읽기 전용 도구만 사용했으므로 사람의 개입 지점도 동일하게 0회였다.
+
+
+
+실행 명령은 다음과 같다.
+
+
+
+`python run\_ab.py --runs 3`
+
+
+
+\## 2. Measurements
+
+
+
+| run | harness | success | tokens | iters | interventions | note |
+
+|---:|---|:---:|---:|---:|---:|---|
+
+| 1 | react | O | 15395 | 5 | 0 | |
+
+| 2 | react | O | 11782 | 4 | 0 | |
+
+| 3 | react | O | 8838 | 4 | 0 | |
+
+| 4 | plan\_exec | O | 15382 | 7 | 0 | replans=1 |
+
+| 5 | plan\_exec | X | 225 | 1 | 0 | replans=0 |
+
+| 6 | plan\_exec | X | 738 | 1 | 0 | replans=0 |
+
+
+
+ReAct의 성공률은 3/3이며 평균 토큰은 12,005개, 평균 반복 횟수는 4.33회였다. Plan-then-Execute의 성공률은 1/3이며 평균 토큰은 약 5,448개, 평균 반복 횟수는 3회였다.
+
+
+
+\## 3. Interpretation
+
+
+
+이 태스크에서는 ReAct가 성공률에서 우세했다. ReAct는 세 번 모두 성공했으며, 매 단계의 Observation을 다음 판단에 반영하는 오류 복구 방식이 안정성에 기여했다. 반면 Plan-then-Execute는 한 번만 성공했고 두 번은 계획 생성 호출 1회 후 종료되었다. 5번과 6번 실행은 반복 횟수가 1이고 재계획도 0회이므로, 실행 단계에 들어가기 전 계획을 유효한 JSON으로 파싱하지 못한 실패임을 로그에서 확인할 수 있다. Plan 방식의 평균 토큰이 더 적은 것은 단순히 효율성이 높아서가 아니라 두 실행이 초기에 실패했기 때문이다. 유일하게 성공한 Plan 실행은 재계획 1회를 사용했고, ReAct의 각 성공 실행보다 많은 7회 호출과 15,382토큰을 소비했다. 따라서 이번 실험에서는 ReAct의 단계별 컨텍스트 갱신과 유연한 오류 복구가 성공률을 높였고, Plan-then-Execute의 엄격한 계획 형식과 제한된 재계획 조건은 초기 계획 오류에 취약하게 작용했다.
+

submissions/26512076/week-02/TASK.md

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+# Task
+
+The same task for both harnesses. `run_ab.py` reads the `task:` and
+`expected:` lines below. Write the success criterion before you run
+anything, and do not change it after you see the results.
+
+task: In app.log, which hour (HH:00) has the most ERROR lines? Answer with the hour in HH:00 form.
+
+## Success criterion
+
+A run succeeds when the final answer contains the hour with the most ERROR
+lines in `app.log`, written as HH:00. `app.log` is the reference input; the
+graded runs use it unchanged.
+
+expected: 14:00

submissions/26512076/week-02/app.log

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+2026-09-01 09:07:27 INFO  job finished in 320ms
+2026-09-01 09:11:56 ERROR NullReference in QuizService.score
+2026-09-01 09:13:14 INFO  health check ok
+2026-09-01 09:26:45 INFO  health check ok
+2026-09-01 09:30:17 INFO  health check ok
+2026-09-01 09:32:05 INFO  request served /api/quiz
+2026-09-01 10:07:50 INFO  session started
+2026-09-01 10:12:15 INFO  request served /api/quiz
+2026-09-01 10:18:22 ERROR db connection refused
+2026-09-01 10:23:48 WARN  retrying upstream call
+2026-09-01 10:53:22 WARN  slow query 1.8s on rooms
+2026-09-01 10:54:07 ERROR NullReference in QuizService.score
+2026-09-01 10:57:10 INFO  cache hit for room 4412
+2026-09-01 11:23:35 ERROR payment webhook signature mismatch
+2026-09-01 11:36:12 INFO  cache hit for room 4412
+2026-09-01 11:39:20 INFO  request served /api/quiz
+2026-09-01 11:40:27 WARN  slow query 1.8s on rooms
+2026-09-01 11:44:02 INFO  health check ok
+2026-09-01 11:56:13 INFO  request served /api/quiz
+2026-09-01 12:08:13 INFO  request served /api/quiz
+2026-09-01 12:28:08 ERROR upstream timeout after 5000ms
+2026-09-01 12:32:19 INFO  health check ok
+2026-09-01 12:49:54 ERROR db connection refused
+2026-09-01 12:50:06 WARN  token near expiry
+2026-09-01 12:53:48 ERROR upstream timeout after 5000ms
+2026-09-01 12:59:50 WARN  token near expiry
+2026-09-01 13:24:27 INFO  cache hit for room 4412
+2026-09-01 13:26:02 INFO  session started
+2026-09-01 13:28:15 INFO  request served /api/quiz
+2026-09-01 13:42:13 ERROR db connection refused
+2026-09-01 13:43:37 WARN  slow query 1.8s on rooms
+2026-09-01 13:59:54 ERROR upstream timeout after 5000ms
+2026-09-01 14:04:06 ERROR NullReference in QuizService.score
+2026-09-01 14:07:11 ERROR NullReference in QuizService.score
+2026-09-01 14:15:56 ERROR upstream timeout after 5000ms
+2026-09-01 14:19:13 INFO  health check ok
+2026-09-01 14:26:19 INFO  request served /api/quiz
+2026-09-01 14:30:20 ERROR db connection refused
+2026-09-01 14:43:37 INFO  job finished in 320ms
+2026-09-01 14:47:03 ERROR upstream timeout after 5000ms
+2026-09-01 14:54:53 ERROR upstream timeout after 5000ms
+2026-09-01 15:04:23 INFO  cache hit for room 4412
+2026-09-01 15:33:16 INFO  request served /api/quiz
+2026-09-01 15:34:38 ERROR payment webhook signature mismatch
+2026-09-01 15:39:25 INFO  cache hit for room 4412
+2026-09-01 15:41:14 ERROR NullReference in QuizService.score
+2026-09-01 15:45:36 INFO  cache hit for room 4412
+2026-09-01 15:48:41 WARN  token near expiry
+2026-09-01 16:11:35 INFO  request served /api/quiz
+2026-09-01 16:16:04 INFO  cache hit for room 4412
+2026-09-01 16:24:31 WARN  slow query 1.8s on rooms
+2026-09-01 16:44:46 INFO  session started
+2026-09-01 16:51:30 WARN  retrying upstream call
+2026-09-01 16:53:34 ERROR NullReference in QuizService.score
+2026-09-01 17:17:14 ERROR NullReference in QuizService.score
+2026-09-01 17:27:48 WARN  token near expiry
+2026-09-01 17:37:46 INFO  health check ok
+2026-09-01 17:48:38 WARN  token near expiry
+2026-09-01 17:55:29 INFO  job finished in 320ms
+2026-09-01 17:56:05 INFO  cache hit for room 4412

submissions/26512076/week-02/harness_plan_execute.py

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+"""Week 02 starter — the Plan-then-Execute harness.
+
+One call produces the whole plan as a JSON list. Then each step is executed
+in order with tools. If a step reports OFF_PLAN, the plan is rebuilt once
+(max_replan=1): that number is the flexibility cap, and it is explicit.
+"""
+import json
+import re
+import sys
+
+from tools_shared import Chat, Meter, Reply
+
+SYSTEM_PLAN = (
+    "You are a planner. Reply with a JSON list of short strings, one per step, "
+    "and nothing else. No prose, no code fences."
+)
+SYSTEM_EXEC = (
+    "You execute one step of a plan at a time with the tools you are given. "
+    "If the step cannot be done as planned, reply with a line that starts with "
+    "'OFF_PLAN:' and explain why. When asked for the final answer, reply with a "
+    "line that starts with 'Answer:'."
+)
+
+
+def parse_plan(text: str):
+    """Return a list of step strings, or None if the model did not give JSON."""
+    text = re.sub(r"^```(?:json)?|```$", "", text.strip(), flags=re.M).strip()
+    try:
+        plan = json.loads(text)
+    except json.JSONDecodeError:
+        return None
+    if isinstance(plan, list) and all(isinstance(s, str) for s in plan):
+        return plan
+    return None
+
+
+def run_plan_execute(task: str, max_replan: int = 1,
+                     max_tool_rounds: int = 3, log=print):
+    meter = Meter()
+
+    # 1) PLAN: the whole plan in one call, no tools
+    planner = Chat(SYSTEM_PLAN, meter, tools=False)
+    planner.add_user(f"Task: {task}\nAvailable tools: read_file(path), "
+                     f"count_pattern(path, pattern).")
+    raw = planner.send().text
+    plan = parse_plan(raw)
+    if plan is None:                              # a parse failure is one failure mode
+        log(f"[plan] not valid JSON: {raw.strip()[:300]!r}")
+        return "plan parse failed", meter, 0
+    log(f"[plan] {plan}")
+
+    # 2) EXECUTE: each step in order
+    executor = Chat(SYSTEM_EXEC, meter)
+    executor.add_user(f"Task: {task}\nPlan: {json.dumps(plan)}")
+    replans = 0
+    i = 0
+    while i < len(plan):
+        executor.add_user(f"Execute step {i + 1}: {plan[i]}")
+        reply = executor.send()
+        rounds = 0
+        while reply.tool_calls:                   # tool calls inside one step
+            executor.run_tools(reply, log)
+            reply = executor.send()
+            rounds += 1
+            if rounds >= max_tool_rounds and reply.tool_calls:
+                executor.run_tools(reply, log)    # answer every call so the transcript stays valid
+                reply = Reply("OFF_PLAN: step exceeded the tool-call budget", [])
+                break
+        log(f"[step {i + 1}] {reply.text.strip()[:300]}")
+
+        if reply.text.strip().startswith("OFF_PLAN") and replans < max_replan:
+            replans += 1                          # flexibility cap
+            planner.add_user(f"Step {i + 1} ({plan[i]}) failed: {reply.text.strip()[:300]}\n"
+                             f"Reply with a JSON list of the remaining steps.")
+            raw = planner.send().text
+            new_steps = parse_plan(raw)
+            if new_steps is None:
+                log(f"[replan] not valid JSON: {raw.strip()[:300]!r}")
+                break
+            plan = plan[:i] + new_steps
+            log(f"[replan] {plan}")
+            continue
+        i += 1
+
+    executor.add_user("Give the final answer now, starting with 'Answer:'.")
+    final = executor.send()
+    if final.tool_calls:                          # the model tried to keep going
+        executor.run_tools(final, log)
+        final = executor.send()
+    return final.text, meter, replans
+
+
+if __name__ == "__main__":
+    task = sys.argv[1] if len(sys.argv) > 1 else \
+        "In app.log, which hour (HH:00) has the most ERROR lines? Answer with the hour in HH:00 form."
+    answer, m, replans = run_plan_execute(task)
+    print(answer)
+    print(f"tokens={m.tokens} iters={m.iters} interventions={m.interventions} replans={replans}")

submissions/26512076/week-02/harness_react.py

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+"""Week 02 starter — the ReAct-style harness.
+
+Every step: the model writes a Thought, calls a tool (Action), sees the result
+(Observation), and decides again. The five axes from the lecture are marked.
+"""
+import sys
+
+from tools_shared import Chat, Meter
+
+SYSTEM = (
+    "You solve tasks with the tools you are given. Before every tool call, "
+    "write one line that starts with 'Thought:' saying what you know and what "
+    "you will do next. When the task is complete, reply with a line that starts "
+    "with 'Answer:' and make no tool call."
+)
+
+# [axis 5] calls that must be approved by a human before they run.
+# The starter tools are read-only, so this set is empty and interventions
+# stay at 0. Add a tool that writes or deletes, and put its name here.
+IRREVERSIBLE = set()
+
+
+def ask_human(call) -> bool:
+    answer = input(f"approve {call.name}({call.args})? [y/N] ").strip().lower()
+    return answer == "y"
+
+
+def run_react(task: str, max_steps: int = 8, log=print):
+    meter = Meter()
+    chat = Chat(SYSTEM, meter)                    # [axis 1] context: full history, every call
+    chat.add_user(task)
+
+    for step in range(max_steps):                 # [axis 3] termination: iteration cap
+        reply = chat.send()
+        if reply.text.strip():
+            log(f"[step {step + 1}] {reply.text.strip()}")
+
+        if not reply.tool_calls:                  # [axis 3] the model chose to finish
+            return reply.text, meter
+
+        approved = []
+        for call in reply.tool_calls:
+            if call.name in IRREVERSIBLE and not ask_human(call):
+                meter.interventions += 1          # [axis 5] intervention point
+                chat.add_tool_result(call, "denied: human did not approve")
+                continue
+            approved.append(call)
+        reply.tool_calls = approved
+        chat.run_tools(reply, log)                # [axis 2] granularity lives in tools_shared
+                                                  # [axis 4] errors come back as Observations
+
+    return "MAX_STEPS reached: incomplete", meter
+
+
+if __name__ == "__main__":
+    task = sys.argv[1] if len(sys.argv) > 1 else \
+        "In app.log, which hour (HH:00) has the most ERROR lines? Answer with the hour in HH:00 form."
+    answer, m = run_react(task)
+    print(answer)
+    print(f"tokens={m.tokens} iters={m.iters} interventions={m.interventions}")

submissions/26512076/week-02/logs/plan_exec-04.txt

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+[plan] ['Read app.log', 'For each hour 00-23, count lines matching "^HH:00.*ERROR"', 'Select hour with highest count', 'Return that hour in HH:00 format']
+  [tool] read_file({'path': 'app.log'}) -> 2026-09-01 09:07:27 INFO  job finished in 320ms | 2026-09-01 09:11:56 ERROR NullReference in QuizService.score | 2026-09-01 09:13:14 INFO  health check ok | 2026-09-01 09:26:45 INFO  health check ok | 2026-09
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 00:00.*ERROR'}) -> 0
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 09:.*ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 10:.*ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 11:.*ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 12:.*ERROR'}) -> 3
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 13:.*ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 14:.*ERROR'}) -> 6
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 15:.*ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 16:.*ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 17:.*ERROR'}) -> 1
+[step 1] OFF_PLAN: step exceeded the tool-call budget
+[replan] not valid JSON: 'User Safety: safe\nResponse Safety: safe'
+[final] Answer: 14:00
+[judge] expected='14:00' -> O (95.2s)

submissions/26512076/week-02/logs/plan_exec-05.txt

@@ -0,0 +1,3 @@
+[plan] not valid JSON: '{"analysis": "I need to find which hour has the most ERROR lines in app.log. I\'ll first read the file to understand its format, then count ERROR lines per hour.", "plan": "1. Read app.log to see the format and identify ERROR lines.\\n2. Use count_pattern to count ERROR lines for each hour.\\n3. Determ'
+[final] plan parse failed
+[judge] expected='14:00' -> X (1.1s)

submissions/26512076/week-02/logs/plan_exec-06.txt

@@ -0,0 +1,3 @@
+[plan] not valid JSON: 'User Safety: safe'
+[final] plan parse failed
+[judge] expected='14:00' -> X (2.9s)

submissions/26512076/week-02/logs/react-01.txt

@@ -0,0 +1,16 @@
+  [tool] read_file({'path': 'app.log'}) -> 2026-09-01 09:07:27 INFO  job finished in 320ms | 2026-09-01 09:11:56 ERROR NullReference in QuizService.score | 2026-09-01 09:13:14 INFO  health check ok | 2026-09-01 09:26:45 INFO  health check ok | 2026-09
+  [tool] count_pattern({'pattern': '^', 'path': 'app.log'}) -> 60
+[step 3] Let me count ERROR lines by hour:
+  [tool] count_pattern({'path': 'app.log', 'pattern': 'ERROR'}) -> 19
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 09:\\d{2}:\\d{2}.*ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 10:\\d{2}:\\d{2}.*ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 11:\\d{2}:\\d{2}.*ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 12:\\d{2}:\\d{2}.*ERROR'}) -> 3
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 13:\\d{2}:\\d{2}.*ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 14:\\d{2}:\\d{2}.*ERROR'}) -> 6
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 15:\\d{2}:\\d{2}.*ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 16:\\d{2}:\\d{2}.*ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 17:\\d{2}:\\d{2}.*ERROR'}) -> 1
+[step 5] Answer: 14:00
+[final] Answer: 14:00
+[judge] expected='14:00' -> O (94.3s)

submissions/26512076/week-02/logs/react-02.txt

@@ -0,0 +1,13 @@
+  [tool] read_file({'path': 'app.log'}) -> 2026-09-01 09:07:27 INFO  job finished in 320ms | 2026-09-01 09:11:56 ERROR NullReference in QuizService.score | 2026-09-01 09:13:14 INFO  health check ok | 2026-09-01 09:26:45 INFO  health check ok | 2026-09
+  [tool] count_pattern({'path': 'app.log', 'pattern': 'ERROR'}) -> 19
+  [tool] count_pattern({'path': 'app.log', 'pattern': '09:[0-9]{2}:[0-9]{2} ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '10:[0-9]{2}:[0-9]{2} ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '11:[0-9]{2}:[0-9]{2} ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '12:[0-9]{2}:[0-9]{2} ERROR'}) -> 3
+  [tool] count_pattern({'path': 'app.log', 'pattern': '13:[0-9]{2}:[0-9]{2} ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '14:[0-9]{2}:[0-9]{2} ERROR'}) -> 6
+  [tool] count_pattern({'path': 'app.log', 'pattern': '15:[0-9]{2}:[0-9]{2} ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '17:[0-9]{2}:[0-9]{2} ERROR'}) -> 1
+[step 4] Answer: 14:00
+[final] Answer: 14:00
+[judge] expected='14:00' -> O (23.1s)

submissions/26512076/week-02/logs/react-03.txt

@@ -0,0 +1,17 @@
+[step 1] Thought: I need to read the app.log file to find ERROR lines and count them by hour.
+
+Let me first read the file to understand its structure.
+  [tool] read_file({'path': 'app.log'}) -> 2026-09-01 09:07:27 INFO  job finished in 320ms | 2026-09-01 09:11:56 ERROR NullReference in QuizService.score | 2026-09-01 09:13:14 INFO  health check ok | 2026-09-01 09:26:45 INFO  health check ok | 2026-09
+[step 2] Thought: I can see the log entries. Now I need to count ERROR lines by hour. Let me use a pattern to count ERROR lines for each hour to be precise.
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 09:.* ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 10:.* ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 11:.* ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 12:.* ERROR'}) -> 3
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 13:.* ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 14:.* ERROR'}) -> 6
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 15:.* ERROR'}) -> 2
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 16:.* ERROR'}) -> 1
+  [tool] count_pattern({'path': 'app.log', 'pattern': '^2026-09-01 17:.* ERROR'}) -> 1
+[step 4] Answer: 14:00
+[final] Answer: 14:00
+[judge] expected='14:00' -> O (72.0s)

submissions/26512076/week-02/results.csv

@@ -0,0 +1,7 @@
+run,harness,success,tokens,iters,interventions,note
+1,react,O,15395,5,0,
+2,react,O,11782,4,0,
+3,react,O,8838,4,0,
+4,plan_exec,O,15382,7,0,replans=1
+5,plan_exec,X,225,1,0,replans=0
+6,plan_exec,X,738,1,0,replans=0