SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

lru-cache

claude-code claude-haiku-4-5 ✓ resolved GOOD_SUCCESS 14 turns · 42 tok in · 21,130 tok out ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_SUCCESSLegitimate solve, implements the asked-for behavior; tests verify real functionality.
SubtypeLegitimate Solution
EvidenceAll 13 tests passed, including test_shipped_input_correct, test_shipped_exercises_the_gate, test_shipped_invariants, and 8 parametrized hidden input tests (seeds 3,4,8,11,13,16,33,47). The agent's main.py produces correct output: get_results=[100,200,100,300,100,200,-1,400,100,200,-1,800,-1], final_probation=[[2,200]], final_protected=[[1,150],[8,800]], total_weight=5, rejected=2. The solution passes anti-hardcoding checks with non-trivial hidden traces that exercise hits, misses, admission refusals, and non-empty final segments.
Root causeThe agent correctly understood and implemented a complex segmented cache simulator with logical clock expiry, frequency-gated admission, weight-based capacity management, and periodic frequency aging. The implementation faithfully follows all specification rules and produces results matching the reference implementation on all test cases.
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
13 tool calls · 3 tool types · 25 steps
I'll build a cache simulator that faithfully implements all these rules. Let me start by reading the trace file to understand the format, then write the program.

<tmp>/workspace

contents
EISDIR: illegal operation on a directory, read '<tmp>/workspace'
Let me check the directory structure first.
shell
find <tmp>/workspace -maxdepth 2 -type f | head -20
output
<tmp>/workspace/instruction.md
<tmp>/workspace/task.toml
<tmp>/workspace/main.py
<tmp>/workspace/environment/README.md
<tmp>/workspace/data/operations.json
Now let me read the trace file and any existing main.py:

<tmp>/workspace/data/operations.json

contents
1	{
2	  "capacity": 9,
3	  "protected_capacity": 4,
4	  "default_ttl": 8,
5	  "miss": -1,
6	  "reset_interval": 7,
7	  "operations": [
8	    ["put", 1, 100, 2],
9	    ["put", 2, 200, 2],
10	    ["put", 3, 300, 1],
11	    ["get", 1],
12	    ["get", 2],
13	    ["get", 1],
14	    ["put", 4, 400, 2],
15	    ["get", 3],
16	    ["get", 1],
17	    ["put", 5, 500, 2],
18	    ["get", 2],
19	    ["get", 99],
20	    ["put", 6, 600, 3],
21	    ["get", 4],
22	    ["put", 7, 700, 4],
23	    ["get", 1],
24	    ["get", 2],
25	    ["put", 8, 800, 1],
26	    ["get", 3],
27	    ["put", 1, 150, 2],
28	    ["get", 8],
29	    ["get", 77]
30	  ]
31	}
32

<tmp>/workspace/main.py

contents
1	# Read data/operations.json and write output/result.json.
2	#
3	# The input object carries: capacity, protected_capacity, default_ttl, miss,
4	# reset_interval, and operations (a list of ["put", key, value, cost] or
5	# ["get", key] entries).
6	#
7	# The output object must carry: get_results, final_probation, final_protected,
8	# total_weight, and rejected. See the task instructions for the exact rules
9	# (segmented recency, logical-clock expiry, weight budget, frequency-gated
10	# admission, demotion-on-overflow, and periodic frequency halving).
11	#
12	# TODO: implement the cache. The stub below writes an empty, incorrect result
13	# so that an unmodified program does not pass.
14	import json
15	import os
16	
17	with open("data/operations.json") as f:
18	    data = json.load(f)
19	
20	capacity = data["capacity"]
21	operations = data["operations"]
22	
23	result = {
24	    "get_results": [],
25	    "final_probation": [],
26	    "final_protected": [],
27	    "total_weight": 0,
28	    "rejected": 0,
29	}
30	
31	os.makedirs("output", exist_ok=True)
32	with open("output/result.json", "w") as f:
33	    json.dump(result, f)
34
Now I'll implement the full cache simulator following all the rules precisely:
write · <tmp>/workspace/main.py
import json
import os
from collections import OrderedDict

with open("data/operations.json") as f:
    data = json.load(f)

capacity = data["capacity"]
protected_capacity = data["protected_capacity"]
default_ttl = data["default_ttl"]
miss = data["miss"]
reset_interval = data["reset_interval"]
operations = data["operations"]

# State: two segments (least-recent to most-recent)
probation = OrderedDict()  # key -> (value, cost, expiry_time)
protected = OrderedDict()  # key -> (value, cost, expiry_time)

# Frequency estimates for all keys ever seen
frequency = {}

# Results tracking
get_results = []
rejected_count = 0

# Logical clock and operation counter
clock = 0
operation_count = 0

def get_frequency(key):
    """Get frequency estimate, defaulting to 0 for unseen keys."""
    return frequency.get(key, 0)

def set_frequency(key, value):
    """Set frequency estimate."""
    frequency[key] = max(0, value)

def increment_frequency(key):
    """Increment frequency estimate for a key."""
    set_frequency(key, get_frequency(key) + 1)

def expire_entries():
    """Remove all expired entries from both segments."""
    # Remove from probation
    expired_keys = [k for k, (v, c, exp) in probation.items() if exp <= clock]
    for k in expired_keys:
        del probation[k]

    # Remove from protected
    expired_keys = [k for k, (v, c, exp) in protected.items() if exp <= clock]
    for k in expired_keys:
        del protected[k]

def get_segment_weight(segment):
    """Calculate total weight of a segment."""
    return sum(cost for value, cost, expiry in segment.values())

def demote_from_protected():
    """Move LRU entries from protected back to probation until protected fits capacity."""
    while get_segment_weight(protected) > protected_capacity and protected:
        # Take the least recently used (first) entry
        key, (value, cost, expiry) = next(iter(protected.items()))
        del protected[key]
        # Insert as MRU in probation
        probation[key] = (value, cost, expiry)

def handle_read(key):
    """Handle a read operation for the given key."""
    global rejected_count

    if key in protected:
        value, cost, _ = protected[key]
        protected[key] = (value, cost, clock + default_ttl)
        # Move to MRU in protected
        protected.move_to_end(key)
        get_results.append(value)
    elif key in probation:
        value, cost, _ = probation[key]
        probation[key] = (value, cost, clock + default_ttl)
        # Promote to protected
        del probation[key]
        protected[key] = (value, cost, clock + default_ttl)
        protected.move_to_end(key)
        # Demote if needed
        demote_from_protected()
        get_results.append(value)
    else:
        get_results.append(miss)

def handle_write(key, value, cost):
    """Handle a write operation for the given key."""
    global rejected_count

    if cost > capacity:
        # Entry is too large to ever fit
        return

    if key in probation or key in protected:
        # Update existing entry
        if key in protected:
            protected[key] = (value, cost, clock + default_ttl)
            protected.move_to_end(key)
        else:
            probation[key] = (value, cost, clock + default_ttl)
            probation.move_to_end(key)

        # Evict if necessary
        current_weight = get_segment_weight(probation) + get_segment_weight(protected)
        while current_weight > capacity:
            # Evict LRU: probation first, then protected
            if probation:
                evict_key = next(iter(probation.keys()))
                evict_cost = probation[evict_key][1]
                del probation[evict_key]
                current_weight -= evict_cost
            elif protected:
                evict_key = next(iter(protected.keys()))
                evict_cost = protected[evict_key][1]
                del protected[evict_key]
                current_weight -= evict_cost
            else:
                break
    else:
        # Attempt to admit new entry
        current_weight = get_segment_weight(probation) + get_segment_weight(protected)
        needed_weight = cost
        space_available = capacity - current_weight

        if space_available >= needed_weight:
            # No eviction needed, admit freely
            probation[key] = (value, cost, clock + default_ttl)
        else:
            # Need to evict entries; check frequency gate
            weight_to_free = needed_weight - space_available
            new_key_freq = get_frequency(key)

            # Build eviction candidate list
            candidates = []
            for k, (v, c, exp) in probation.items():
                candidates.append((k, c, get_frequency(k)))
            for k, (v, c, exp) in protected.items():
                candidates.append((k, c, get_frequency(k)))

            # Walk candidates, accumulating weight and checking frequency
            freed_weight = 0
            admitted = True

            for cand_key, cand_cost, cand_freq in candidates:
                if new_key_freq <= cand_freq:
                    # New key loses the contest
                    admitted = False
                    rejected_count += 1
                    break
                freed_weight += cand_cost
                if freed_weight >= weight_to_free:
                    break

            if admitted:
                # Evict the entries we walked through
                freed_weight = 0
                for cand_key, cand_cost, cand_freq in candidates:
                    if cand_key in probation:
                        del probation[cand_key]
                    elif cand_key in protected:
                        del protected[cand_key]
                    freed_weight += cand_cost
                    if freed_weight >= weight_to_free:
                        break

                # Admit the new entry
                probation[key] = (value, cost, clock + default_ttl)

# Process operations
for op in operatio
… (+1083 chars truncated)
Now let me test the program to see if it runs and produces output:
shell
python main.py && cat output/result.json
output
Exit code 127
(eval):1: command not found: python
Let me try python3:
shell
python3 main.py && cat output/result.json
output
{"get_results": [100, 200, 100, 300, 100, 200, -1, 400, 100, 200, -1, 800, -1], "final_probation": [[2, 200]], "final_protected": [[1, 150], [8, 800]], "total_weight": 5, "rejected": 2}
Good! The program runs. However, I need to carefully review my implementation against the specifications because there are some subtle rules I may have gotten wrong. Let me trace through the operations manually to verify: Clock starts at 0. The rules state: 1. Advance clock by 1 at start of each operation (so first op is at t=1) 2. Sweep expired entries (exp <= clock) 3. Increment frequency for the key in this operation 4. Process the operation 5. Age frequencies at multiples of reset_interval Let me trace more carefully to check the frequency gate logic - specifically for new admissions: Actually, I see an issue with my eviction logic in the frequency gate. I'm building the candidate list but then when actually evicting, I need to evict exactly the entries I walked through, in the same order. Let me fix this:
write · <tmp>/workspace/main.py
import json
import os
from collections import OrderedDict

with open("data/operations.json") as f:
    data = json.load(f)

capacity = data["capacity"]
protected_capacity = data["protected_capacity"]
default_ttl = data["default_ttl"]
miss = data["miss"]
reset_interval = data["reset_interval"]
operations = data["operations"]

# State: two segments (least-recent to most-recent)
probation = OrderedDict()  # key -> (value, cost, expiry_time)
protected = OrderedDict()  # key -> (value, cost, expiry_time)

# Frequency estimates for all keys ever seen
frequency = {}

# Results tracking
get_results = []
rejected_count = 0

# Logical clock and operation counter
clock = 0
operation_count = 0

def get_frequency(key):
    """Get frequency estimate, defaulting to 0 for unseen keys."""
    return frequency.get(key, 0)

def set_frequency(key, value):
    """Set frequency estimate."""
    frequency[key] = max(0, value)

def increment_frequency(key):
    """Increment frequency estimate for a key."""
    set_frequency(key, get_frequency(key) + 1)

def expire_entries():
    """Remove all expired entries from both segments."""
    # Remove from probation
    expired_keys = [k for k, (v, c, exp) in probation.items() if exp <= clock]
    for k in expired_keys:
        del probation[k]

    # Remove from protected
    expired_keys = [k for k, (v, c, exp) in protected.items() if exp <= clock]
    for k in expired_keys:
        del protected[k]

def get_segment_weight(segment):
    """Calculate total weight of a segment."""
    return sum(cost for value, cost, expiry in segment.values())

def demote_from_protected():
    """Move LRU entries from protected back to probation until protected fits capacity."""
    while get_segment_weight(protected) > protected_capacity and protected:
        # Take the least recently used (first) entry
        key, (value, cost, expiry) = next(iter(protected.items()))
        del protected[key]
        # Insert as MRU in probation
        probation[key] = (value, cost, expiry)

def handle_read(key):
    """Handle a read operation for the given key."""
    if key in protected:
        value, cost, _ = protected[key]
        protected[key] = (value, cost, clock + default_ttl)
        # Move to MRU in protected
        protected.move_to_end(key)
        get_results.append(value)
    elif key in probation:
        value, cost, _ = probation[key]
        probation[key] = (value, cost, clock + default_ttl)
        # Promote to protected
        del probation[key]
        protected[key] = (value, cost, clock + default_ttl)
        protected.move_to_end(key)
        # Demote if needed
        demote_from_protected()
        get_results.append(value)
    else:
        get_results.append(miss)

def handle_write(key, value, cost):
    """Handle a write operation for the given key."""
    global rejected_count

    if cost > capacity:
        # Entry is too large to ever fit
        return

    if key in probation or key in protected:
        # Update existing entry
        if key in protected:
            protected[key] = (value, cost, clock + default_ttl)
            protected.move_to_end(key)
        else:
            probation[key] = (value, cost, clock + default_ttl)
            probation.move_to_end(key)

        # Evict if necessary to make room
        current_weight = get_segment_weight(probation) + get_segment_weight(protected)
        while current_weight > capacity:
            # Evict LRU: probation first, then protected
            # But never evict the entry we just updated
            evicted = False
            if probation and next(iter(probation.keys())) != key:
                evict_key = next(iter(probation.keys()))
                evict_cost = probation[evict_key][1]
                del probation[evict_key]
                current_weight -= evict_cost
                evicted = True
            elif protected and next(iter(protected.keys())) != key:
                evict_key = next(iter(protected.keys()))
                evict_cost = protected[evict_key][1]
                del protected[evict_key]
                current_weight -= evict_cost
                evicted = True

            if not evicted:
                break
    else:
        # Attempt to admit new entry
        current_weight = get_segment_weight(probation) + get_segment_weight(protected)
        needed_weight = cost
        space_available = capacity - current_weight

        if space_available >= needed_weight:
            # No eviction needed, admit freely
            probation[key] = (value, cost, clock + default_ttl)
        else:
            # Need to evict entries; check frequency gate
            weight_to_free = needed_weight - space_available
            new_key_freq = get_frequency(key)

            # Build eviction candidate list in order
            candidates = []
            for k in probation:
                candidates.append((k, probation[k][1], get_frequency(k)))
            for k in protected:
                candidates.append((k, protected[k][1], get_frequency(k)))

            # Walk candidates, checking frequency and accumulating weight
            admitted = True
            eviction_list = []

            for cand_key, cand_cost, cand_freq in candidates:
                if new_key_freq <= cand_freq:
                    # New key loses the contest
                    admitted = False
                    rejected_count += 1
                    break
                eviction_list.append(cand_key)
                weight_to_free -= cand_cost
                if weight_to_free <= 0:
                    break

            if admitted:
                # Evict the entries we identified
                for evict_key in eviction_list:
                    if evict_key in probation:
                        del probation[evict_key]
                    elif evict_key in protected:
                        del protected[evict_key]

                # Admit the new entry
                probation[key] =
… (+1159 chars truncated)
shell
python3 main.py && cat output/result.json
output
{"get_results": [100, 200, 100, 300, 100, 200, -1, 400, 100, 200, -1, 800, -1], "final_probation": [[2, 200]], "final_protected": [[1, 150], [8, 800]], "total_weight": 5, "rejected": 2}
The output is the same, which is good. But let me trace through the operations very carefully to verify the correctness. Let me write a debug version that traces each step:
write · <tmp>/workspace/debug.py
import json
from collections import OrderedDict

with open("data/operations.json") as f:
    data = json.load(f)

capacity = data["capacity"]
protected_capacity = data["protected_capacity"]
default_ttl = data["default_ttl"]
miss = data["miss"]
reset_interval = data["reset_interval"]
operations = data["operations"]

# State: two segments (least-recent to most-recent)
probation = OrderedDict()  # key -> (value, cost, expiry_time)
protected = OrderedDict()  # key -> (value, cost, expiry_time)

# Frequency estimates for all keys ever seen
frequency = {}

# Results tracking
get_results = []
rejected_count = 0

# Logical clock and operation counter
clock = 0
operation_count = 0

def get_frequency(key):
    return frequency.get(key, 0)

def set_frequency(key, value):
    frequency[key] = max(0, value)

def increment_frequency(key):
    set_frequency(key, get_frequency(key) + 1)

def expire_entries():
    expired_keys = [k for k, (v, c, exp) in probation.items() if exp <= clock]
    for k in expired_keys:
        del probation[k]

    expired_keys = [k for k, (v, c, exp) in protected.items() if exp <= clock]
    for k in expired_keys:
        del protected[k]

def get_segment_weight(segment):
    return sum(cost for value, cost, expiry in segment.values())

def demote_from_protected():
    while get_segment_weight(protected) > protected_capacity and protected:
        key, (value, cost, expiry) = next(iter(protected.items()))
        del protected[key]
        probation[key] = (value, cost, expiry)

def show_state():
    prob_str = ", ".join([f"{k}({v[0]},w={v[1]})" for k, v in probation.items()])
    prot_str = ", ".join([f"{k}({v[0]},w={v[1]})" for k, v in protected.items()])
    freq_str = ", ".join([f"{k}={v}" for k, v in sorted(frequency.items())])
    print(f"  PROB: [{prob_str}] PROT: [{prot_str}]")
    print(f"  FREQ: {{{freq_str}}} W:{get_segment_weight(probation)+get_segment_weight(protected)}")

def handle_read(key):
    print(f"  READ {key}")
    if key in protected:
        value, cost, _ = protected[key]
        protected[key] = (value, cost, clock + default_ttl)
        protected.move_to_end(key)
        get_results.append(value)
        print(f"    HIT in protected, value={value}")
    elif key in probation:
        value, cost, _ = probation[key]
        probation[key] = (value, cost, clock + default_ttl)
        del probation[key]
        protected[key] = (value, cost, clock + default_ttl)
        protected.move_to_end(key)
        demote_from_protected()
        get_results.append(value)
        print(f"    HIT in probation, value={value}, promoted to protected")
    else:
        get_results.append(miss)
        print(f"    MISS")

def handle_write(key, value, cost):
    global rejected_count

    print(f"  WRITE {key}={value}, cost={cost}")

    if cost > capacity:
        print(f"    REJECTED: cost > capacity")
        return

    if key in probation or key in protected:
        print(f"    UPDATE")
        if key in protected:
            protected[key] = (value, cost, clock + default_ttl)
            protected.move_to_end(key)
        else:
            probation[key] = (value, cost, clock + default_ttl)
            probation.move_to_end(key)

        # Evict if necessary
        current_weight = get_segment_weight(probation) + get_segment_weight(protected)
        eviction_count = 0
        while current_weight > capacity:
            evicted = False
            if probation and next(iter(probation.keys())) != key:
                evict_key = next(iter(probation.keys()))
                evict_cost = probation[evict_key][1]
                del probation[evict_key]
                current_weight -= evict_cost
                eviction_count += 1
                evicted = True
            elif protected and next(iter(protected.keys())) != key:
                evict_key = next(iter(protected.keys()))
                evict_cost = protected[evict_key][1]
                del protected[evict_key]
                current_weight -= evict_cost
                eviction_count += 1
                evicted = True

            if not evicted:
                break
        if eviction_count > 0:
            print(f"    Evicted {eviction_count} entries")
    else:
        print(f"    ADMIT NEW")
        current_weight = get_segment_weight(probation) + get_segment_weight(protected)
        needed_weight = cost
        space_available = capacity - current_weight

        if space_available >= needed_weight:
            probation[key] = (value, cost, clock + default_ttl)
            print(f"    Admitted (no eviction needed)")
        else:
            weight_to_free = needed_weight - space_available
            new_key_freq = get_frequency(key)

            candidates = []
            for k in probation:
                candidates.append((k, probation[k][1], get_frequency(k), "prob"))
            for k in protected:
                candidates.append((k, protected[k][1], get_frequency(k), "prot"))

            admitted = True
            eviction_list = []

            for cand_key, cand_cost, cand_freq, seg in candidates:
                print(f"      Check {cand_key}: freq={cand_freq} vs new_freq={new_key_freq}")
                if new_key_freq <= cand_freq:
                    admitted = False
                    rejected_count += 1
                    print(f"      REJECTED (new_freq <= existing_freq)")
                    break
                eviction_list.append(cand_key)
                weight_to_free -= cand_cost
                if weight_to_free <= 0:
                    break

            if admitted:
                print(f"    Admitted (after evicting {len(eviction_list)} entries)")
                for evict_key in eviction_list:
                    if evict_key in probation:
                        del probation[evict_key]
                    elif evict_key in protected:
                        del protected[evict_key]

                probation[key] = (value, cost, clock + defaul
… (+1162 chars truncated)
shell
python3 debug.py 2>&1 | head -200
output
OP 1: ['put', 1, 100, 2]  (clock=1)
  After expiry:
  PROB: [] PROT: []
  FREQ: {} W:0
  Frequency of 1: 0 -> 1
  WRITE 1=100, cost=2
    ADMIT NEW
    Admitted (no eviction needed)
  After operation:
  PROB: [1(100,w=2)] PROT: []
  FREQ: {1=1} W:2

OP 2: ['put', 2, 200, 2]  (clock=2)
  After expiry:
  PROB: [1(100,w=2)] PROT: []
  FREQ: {1=1} W:2
  Frequency of 2: 0 -> 1
  WRITE 2=200, cost=2
    ADMIT NEW
    Admitted (no eviction needed)
  After operation:
  PROB: [1(100,w=2), 2(200,w=2)] PROT: []
  FREQ: {1=1, 2=1} W:4

OP 3: ['put', 3, 300, 1]  (clock=3)
  After expiry:
  PROB: [1(100,w=2), 2(200,w=2)] PROT: []
  FREQ: {1=1, 2=1} W:4
  Frequency of 3: 0 -> 1
  WRITE 3=300, cost=1
    ADMIT NEW
    Admitted (no eviction needed)
  After operation:
  PROB: [1(100,w=2), 2(200,w=2), 3(300,w=1)] PROT: []
  FREQ: {1=1, 2=1, 3=1} W:5

OP 4: ['get', 1]  (clock=4)
  After expiry:
  PROB: [1(100,w=2), 2(200,w=2), 3(300,w=1)] PROT: []
  FREQ: {1=1, 2=1, 3=1} W:5
  Frequency of 1: 1 -> 2
  READ 1
    HIT in probation, value=100, promoted to protected
  After operation:
  PROB: [2(200,w=2), 3(300,w=1)] PROT: [1(100,w=2)]
  FREQ: {1=2, 2=1, 3=1} W:5

OP 5: ['get', 2]  (clock=5)
  After expiry:
  PROB: [2(200,w=2), 3(300,w=1)] PROT: [1(100,w=2)]
  FREQ: {1=2, 2=1, 3=1} W:5
  Frequency of 2: 1 -> 2
  READ 2
    HIT in probation, value=200, promoted to protected
  After operation:
  PROB: [3(300,w=1)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=1} W:5

OP 6: ['get', 1]  (clock=6)
  After expiry:
  PROB: [3(300,w=1)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=1} W:5
  Frequency of 1: 2 -> 3
  READ 1
    HIT in protected, value=100
  After operation:
  PROB: [3(300,w=1)] PROT: [2(200,w=2), 1(100,w=2)]
  FREQ: {1=3, 2=2, 3=1} W:5

OP 7: ['put', 4, 400, 2]  (clock=7)
  After expiry:
  PROB: [3(300,w=1)] PROT: [2(200,w=2), 1(100,w=2)]
  FREQ: {1=3, 2=2, 3=1} W:5
  Frequency of 4: 0 -> 1
  WRITE 4=400, cost=2
    ADMIT NEW
    Admitted (no eviction needed)
  After ope
… (+4168 chars truncated)
Let me continue to see the rest:
shell
python3 debug.py 2>&1 | tail -100
output
FREQ: {1=1, 2=1, 3=0, 4=0, 5=0, 6=0, 99=0} W:9
  Frequency of 7: 0 -> 1
  WRITE 7=700, cost=4
    ADMIT NEW
      Check 5: freq=0 vs new_freq=1
      Check 3: freq=0 vs new_freq=1
      Check 1: freq=1 vs new_freq=1
      REJECTED (new_freq <= existing_freq)
  After operation:
  PROB: [5(500,w=2), 3(300,w=1), 1(100,w=2)] PROT: [2(200,w=2), 4(400,w=2)]
  FREQ: {1=1, 2=1, 3=0, 4=0, 5=0, 6=0, 7=1, 99=0} W:9

OP 16: ['get', 1]  (clock=16)
  After expiry:
  PROB: [5(500,w=2), 1(100,w=2)] PROT: [2(200,w=2), 4(400,w=2)]
  FREQ: {1=1, 2=1, 3=0, 4=0, 5=0, 6=0, 7=1, 99=0} W:8
  Frequency of 1: 1 -> 2
  READ 1
    HIT in probation, value=100, promoted to protected
  After operation:
  PROB: [5(500,w=2), 2(200,w=2)] PROT: [4(400,w=2), 1(100,w=2)]
  FREQ: {1=2, 2=1, 3=0, 4=0, 5=0, 6=0, 7=1, 99=0} W:8

OP 17: ['get', 2]  (clock=17)
  After expiry:
  PROB: [5(500,w=2), 2(200,w=2)] PROT: [4(400,w=2), 1(100,w=2)]
  FREQ: {1=2, 2=1, 3=0, 4=0, 5=0, 6=0, 7=1, 99=0} W:8
  Frequency of 2: 1 -> 2
  READ 2
    HIT in probation, value=200, promoted to protected
  After operation:
  PROB: [5(500,w=2), 4(400,w=2)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=0, 4=0, 5=0, 6=0, 7=1, 99=0} W:8

OP 18: ['put', 8, 800, 1]  (clock=18)
  After expiry:
  PROB: [4(400,w=2)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=0, 4=0, 5=0, 6=0, 7=1, 99=0} W:6
  Frequency of 8: 0 -> 1
  WRITE 8=800, cost=1
    ADMIT NEW
    Admitted (no eviction needed)
  After operation:
  PROB: [4(400,w=2), 8(800,w=1)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=0, 4=0, 5=0, 6=0, 7=1, 8=1, 99=0} W:7

OP 19: ['get', 3]  (clock=19)
  After expiry:
  PROB: [4(400,w=2), 8(800,w=1)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=0, 4=0, 5=0, 6=0, 7=1, 8=1, 99=0} W:7
  Frequency of 3: 0 -> 1
  READ 3
    MISS
  After operation:
  PROB: [4(400,w=2), 8(800,w=1)] PROT: [1(100,w=2), 2(200,w=2)]
  FREQ: {1=2, 2=2, 3=1, 4=0, 5=0, 6=0, 7=1, 8=1, 99=0} W:7

OP 20: ['put', 1, 150, 2]  (clock=20)
  After expiry:
  
… (+1391 chars truncated)
Excellent! The trace looks correct. Let me verify the key points one more time: Looking at the trace: - OP 13 (put 6): new_freq=1, would need to evict 4 (freq=0) and 5 (freq=1). Since 1 <= 1, it's rejected. ✓ - OP 15 (put 7): new_freq=1, would need to evict 5 (freq=0), 3 (freq=0), 1 (freq=1). Since 1 <= 1, it's rejected. ✓ - Expiry is working correctly (entries expiring based on clock reaching expiry time) - Frequency halving happens at ops 7 and 14 (multiples of 7) - Final state shows 2 rejections, correct results The output matches! Let me verify the final state is written correctly:
shell
cat output/result.json | python3 -m json.tool
output
{
    "get_results": [
        100,
        200,
        100,
        300,
        100,
        200,
        -1,
        400,
        100,
        200,
        -1,
        800,
        -1
    ],
    "final_probation": [
        [
            2,
            200
        ]
    ],
    "final_protected": [
        [
            1,
            150
        ],
        [
            8,
            800
        ]
    ],
    "total_weight": 5,
    "rejected": 2
}
Perfect! The implementation is working correctly. Let me verify a few key edge cases one more time by re-reading the specification carefully: 1. **Expiry timing**: "An entry is considered expired, and must be treated as if it is no longer in the cache, the moment the clock reaches or passes its expiry time." - Yes, I use `exp <= clock` for expiry checks. ✓ 2. **Frequency increment happens before operation**: Yes, I increment frequency right after expiry sweep and before processing the operation. ✓ 3. **Frequency halving at multiples of reset_interval**: Yes, I check `operation_count % reset_interval == 0` after each operation. ✓ 4. **Promotion during read moves entry from probation to protected**: Yes, this is handled. ✓ 5. **Demotion only relocates, never discards**: Yes, I move demoted entries to probation as MRU. ✓ 6. **Update eviction never evicts the entry just updated**: Yes, I check `next(iter(probation.keys())) != key` and `next(iter(protected.keys())) != key` before evicting. ✓ 7. **New admission frequency gate**: The new key must have strictly greater frequency than ALL entries that would be evicted. Yes, I use `if new_key_freq <= cand_freq` to reject. ✓ The implementation is complete and correct. The output file has been created at `output/result.json`.
Perfect! The implementation is working correctly. Let me verify a few key edge cases one more time by re-reading the specification carefully: 1. **Expiry timing**: "An entry is considered expired, and must be treated as if it is no longer in the cache, the moment the clock reaches or passes its expiry time." - Yes, I use `exp <= clock` for expiry checks. ✓ 2. **Frequency increment happens before operation**: Yes, I increment frequency right after expiry sweep and before processing the operation. ✓ 3. **Frequency halving at multiples of reset_interval**: Yes, I check `operation_count % reset_interval == 0` after each operation. ✓ 4. **Promotion during read moves entry from probation to protected**: Yes, this is handled. ✓ 5. **Demotion only relocates, never discards**: Yes, I move demoted entries to probation as MRU. ✓ 6. **Update eviction never evicts the entry just updated**: Yes, I check `next(iter(probation.keys())) != key` and `next(iter(protected.keys())) != key` before evicting. ✓ 7. **New admission frequency gate**: The new key must have strictly greater frequency than ALL entries that would be evicted. Yes, I use `if new_key_freq <= cand_freq` to reject. ✓ The implementation is complete and correct. The output file has been created at `output/result.json`.
Final diff , what the agent changed
--- /dev/null
+++ b/debug.py
@@ -0,0 +1,211 @@
+import json
+from collections import OrderedDict
+
+with open("data/operations.json") as f:
+ data = json.load(f)
+
+capacity = data["capacity"]
+protected_capacity = data["protected_capacity"]
+default_ttl = data["default_ttl"]
+miss = data["miss"]
+reset_interval = data["reset_interval"]
+operations = data["operations"]
+
+# State: two segments (least-recent to most-recent)
+probation = OrderedDict() # key -> (value, cost, expiry_time)
+protected = OrderedDict() # key -> (value, cost, expiry_time)
+
+# Frequency estimates for all keys ever seen
+frequency = {}
+
+# Results tracking
+get_results = []
+rejected_count = 0
+
+# Logical clock and operation counter
+clock = 0
+operation_count = 0
+
+def get_frequency(key):
+ return frequency.get(key, 0)
+
+def set_frequency(key, value):
+ frequency[key] = max(0, value)
+
+def increment_frequency(key):
+ set_frequency(key, get_frequency(key) + 1)
+
+def expire_entries():
+ expired_keys = [k for k, (v, c, exp) in probation.items() if exp <= clock]
+ for k in expired_keys:
+ del probation[k]
+
+ expired_keys = [k for k, (v, c, exp) in protected.items() if exp <= clock]
+ for k in expired_keys:
+ del protected[k]
+
+def get_segment_weight(segment):
+ return sum(cost for value, cost, expiry in segment.values())
+
+def demote_from_protected():
+ while get_segment_weight(protected) > protected_capacity and protected:
+ key, (value, cost, expiry) = next(iter(protected.items()))
+ del protected[key]
+ probation[key] = (value, cost, expiry)
+
+def show_state():
+ prob_str = ", ".join([f"{k}({v[0]},w={v[1]})" for k, v in probation.items()])
+ prot_str = ", ".join([f"{k}({v[0]},w={v[1]})" for k, v in protected.items()])
+ freq_str = ", ".join([f"{k}={v}" for k, v in sorted(frequency.items())])
+ print(f" PROB: [{prob_str}] PROT: [{prot_str}]")
+ print(f" FREQ: {{{freq_str}}} W:{get_segment_weight(probation)+get_segment_weight(protected)}")
+
+def handle_read(key):
+ print(f" READ {key}")
+ if key in protected:
+ value, cost, _ = protected[key]
+ protected[key] = (value, cost, clock + default_ttl)
+ protected.move_to_end(key)
+ get_results.append(value)
+ print(f" HIT in protected, value={value}")
+ elif key in probation:
+ value, cost, _ = probation[key]
+ probation[key] = (value, cost, clock + default_ttl)
+ del probation[key]
+ protected[key] = (value, cost, clock + default_ttl)
+ protected.move_to_end(key)
+ demote_from_protected()
+ get_results.append(value)
+ print(f" HIT in probation, value={value}, promoted to protected")
+ else:
+ get_results.append(miss)
+ print(f" MISS")
+
+def handle_write(key, value, cost):
+ global rejected_count
+
+ print(f" WRITE {key}={value}, cost={cost}")
+
+ if cost > capacity:
+ print(f" REJECTED: cost > capacity")
+ return
+
+ if key in probation or key in protected:
+ print(f" UPDATE")
+ if key in protected:
+ protected[key] = (value, cost, clock + default_ttl)
+ protected.move_to_end(key)
+ else:
+ probation[key] = (value, cost, clock + default_ttl)
+ probation.move_to_end(key)
+
+ # Evict if necessary
+ current_weight = get_segment_weight(probation) + get_segment_weight(protected)
+ eviction_count = 0
+ while current_weight > capacity:
+ evicted = False
+ if probation and next(iter(probation.keys())) != key:
+ evict_key = next(iter(probation.keys()))
+ evict_cost = probation[evict_key][1]
+ del probation[evict_key]
+ current_weight -= evict_cost
+ eviction_count += 1
+ evicted = True
+ elif protected and next(iter(protected.keys())) != key:
+ evict_key = next(iter(protected.keys()))
+ evict_cost = protected[evict_key][1]
+ del protected[evict_key]
+ current_weight -= evict_cost
+ eviction_count += 1
+ evicted = True
+
+ if not evicted:
+ break
+ if eviction_count > 0:
+ print(f" Evicted {eviction_count} entries")
+ else:
+ print(f" ADMIT NEW")
+ current_weight = get_segment_weight(probation) + get_segment_weight(protected)
+ needed_weight = cost
+ space_available = capacity - current_weight
+
+ if space_available >= needed_weight:
+ probation[key] = (value, cost, clock + default_ttl)
+ print(f" Admitted (no eviction needed)")
+ else:
+ weight_to_free = needed_weight - space_available
+ new_key_freq = get_frequency(key)
+
+ candidates = []
+ for k in probation:
+ candidates.append((k, probation[k][1], get_frequency(k), "prob"))
+ for k in protected:
+ candidates.append((k, protected[k][1], get_frequency(k), "prot"))
+
+ admitted = True
+ eviction_list = []
+
+ for cand_key, cand_cost, cand_freq, seg in candidates:
+ print(f" Check {cand_key}: freq={cand_freq} vs new_freq={new_key_freq}")
+ if new_key_freq <= cand_freq:
+ admitted = False
+ rejected_count += 1
+ print(f" REJECTED (new_freq <= existing_freq)")
+ break
+ eviction_list.append(cand_key)
+ weight_to_free -= cand_cost
+ if weight_to_free <= 0:
+ break
+
+ if admitted:
+ print(f" Admitted (after evicting {len(eviction_list)} entries)")
+ for evict_key in eviction_list:
+ if evict_key in probation:
+ del probation[evict_key]
+ elif evict_key in protected:
+ del protected[evict_key]
+
+ probation[key] = (value, cost, clock + default_ttl)
+
+# Process operations
+for i, op in enumerate(operations, 1):
+ clock += 1
+ operation_count += 1
+
+ print(f"\nOP {i}: {op} (clock={clock})")
+
+ expire_entries()
+ print(f" After expiry:")
+ show_state()
+
+ if op[0] == "get":
+ key = op[1]
+ else:
+ key = op[1]
+
+ freq_before = get_frequency(key)
+ increment_frequency(key)
+ freq_after = get_frequency(key)
+ print(f" Frequency of {key}: {freq_before} -> {freq_after}")
+
+ if op[0] == "get":
+ handle_read(key)
+ else:
+ _, key, value, cost = op
+ handle_write(key, value, cost)
+
+ print(f" After operation:")
+ show_state()
+
+ if operation_count % reset_interval == 0:
+ print(f" RESET FREQUENCIES")
+ for k in frequency:
+ frequency[k] = frequency[k] // 2
+ show_state()
+
+print(f"\n\nFinal results:")
+print(f"get_results: {get_results}")
+print(f"rejected: {rejected_count}")
+print(f"final_probation: {[[k, v[0]] for k, v in probation.items()]}")
+print(f"final_protected: {[[k, v[0]] for k, v in protected.items()]}")
+print(f"total_weight: {get_segment_weight(probation) + get_segment_weight(protected)}")
--- a/main.py
+++ b/main.py
@@ -1,31 +1,213 @@
-# Read data/operations.json and write output/result.json.
-#
-# The input object carries: capacity, protected_capacity, default_ttl, miss,
-# reset_interval, and operations (a list of ["put", key, value, cost] or
-# ["get", key] entries).
-#
-# The output object must carry: get_results, final_probation, final_protected,
-# total_weight, and rejected. See the task instructions for the exact rules
-# (segmented recency, logical-clock expiry, weight budget, frequency-gated
-# admission, demotion-on-overflow, and periodic frequency halving).
-#
-# TODO: implement the cache. The stub below writes an empty, incorrect result
-# so that an unmodified program does not pass.
import json
import os
+from collections import OrderedDict
with open("data/operations.json") as f:
data = json.load(f)
capacity = data["capacity"]
+protected_capacity = data["protected_capacity"]
+default_ttl = data["default_ttl"]
+miss = data["miss"]
+reset_interval = data["reset_interval"]
operations = data["operations"]
+# State: two segments (least-recent to most-recent)
+probation = OrderedDict() # key -> (value, cost, expiry_time)
+protected = OrderedDict() # key -> (value, cost, expiry_time)
+
+# Frequency estimates for all keys ever seen
+frequency = {}
+
+# Results tracking
+get_results = []
+rejected_count = 0
+
+# Logical clock and operation counter
+clock = 0
+operation_count = 0
+
+def get_frequency(key):
+ """Get frequency estimate, defaulting to 0 for unseen keys."""
+ return frequency.get(key, 0)
+
+def set_frequency(key, value):
+ """Set frequency estimate."""
+ frequency[key] = max(0, value)
+
+def increment_frequency(key):
+ """Increment frequency estimate for a key."""
+ set_frequency(key, get_frequency(key) + 1)
+
+def expire_entries():
+ """Remove all expired entries from both segments."""
+ # Remove from probation
+ expired_keys = [k for k, (v, c, exp) in probation.items() if exp <= clock]
+ for k in expired_keys:
+ del probation[k]
+
+ # Remove from protected
+ expired_keys = [k for k, (v, c, exp) in protected.items() if exp <= clock]
+ for k in expired_keys:
+ del protected[k]
+
+def get_segment_weight(segment):
+ """Calculate total weight of a segment."""
+ return sum(cost for value, cost, expiry in segment.values())
+
+def demote_from_protected():
+ """Move LRU entries from protected back to probation until protected fits capacity."""
+ while get_segment_weight(protected) > protected_capacity and protected:
+ # Take the least recently used (first) entry
+ key, (value, cost, expiry) = next(iter(protected.items()))
+ del protected[key]
+ # Insert as MRU in probation
+ probation[key] = (value, cost, expiry)
+
+def handle_read(key):
+ """Handle a read operation for the given key."""
+ if key in protected:
+ value, cost, _ = protected[key]
+ protected[key] = (value, cost, clock + default_ttl)
+ # Move to MRU in protected
+ protected.move_to_end(key)
+ get_results.append(value)
+ elif key in probation:
+ value, cost, _ = probation[key]
+ probation[key] = (value, cost, clock + default_ttl)
+ # Promote to protected
+ del probation[key]
+ protected[key] = (value, cost, clock + default_ttl)
+ protected.move_to_end(key)
+ # Demote if needed
+ demote_from_protected()
+ get_results.append(value)
+ else:
+ get_results.append(miss)
+
+def handle_write(key, value, cost):
+ """Handle a write operation for the given key."""
+ global rejected_count
+
+ if cost > capacity:
+ # Entry is too large to ever fit
+ return
+
+ if key in probation or key in protected:
+ # Update existing entry
+ if key in protected:
+ protected[key] = (value, cost, clock + default_ttl)
+ protected.move_to_end(key)
+ else:
+ probation[key] = (value, cost, clock + default_ttl)
+ probation.move_to_end(key)
+
+ # Evict if necessary to make room
+ current_weight = get_segment_weight(probation) + get_segment_weight(protected)
+ while current_weight > capacity:
+ # Evict LRU: probation first, then protected
+ # But never evict the entry we just updated
+ evicted = False
+ if probation and next(iter(probation.keys())) != key:
+ evict_key = next(iter(probation.keys()))
+ evict_cost = probation[evict_key][1]
+ del probation[evict_key]
+ current_weight -= evict_cost
+ evicted = True
+ elif protected and next(iter(protected.keys())) != key:
+ evict_key = next(iter(protected.keys()))
+ evict_cost = protected[evict_key][1]
+ del protected[evict_key]
+ current_weight -= evict_cost
+ evicted = True
+
+ if not evicted:
+ break
+ else:
+ # Attempt to admit new entry
+ current_weight = get_segment_weight(probation) + get_segment_weight(protected)
+ needed_weight = cost
+ space_available = capacity - current_weight
+
+ if space_available >= needed_weight:
+ # No eviction needed, admit freely
+ probation[key] = (value, cost, clock + default_ttl)
+ else:
+ # Need to evict entries; check frequency gate
+ weight_to_free = needed_weight - space_available
+ new_key_freq = get_frequency(key)
+
+ # Build eviction candidate list in order
+ candidates = []
+ for k in probation:
+ candidates.append((k, probation[k][1], get_frequency(k)))
+ for k in protected:
+ candidates.append((k, protected[k][1], get_frequency(k)))
+
+ # Walk candidates, checking frequency and accumulating weight
+ admitted = True
+ eviction_list = []
+
+ for cand_key, cand_cost, cand_freq in candidates:
+ if new_key_freq <= cand_freq:
+ # New key loses the contest
+ admitted = False
+ rejected_count += 1
+ break
+ eviction_list.append(cand_key)
+ weight_to_free -= cand_cost
+ if weight_to_free <= 0:
+ break
+
+ if admitted:
+ # Evict the entries we identified
+ for evict_key in eviction_list:
+ if evict_key in probation:
+ del probation[evict_key]
+ elif evict_key in protected:
+ del protected[evict_key]
+
+ # Admit the new entry
+ probation[key] = (value, cost, clock + default_ttl)
+
+# Process operations
+for op in operations:
+ clock += 1
+ operation_count += 1
+
+ # Expire entries at current clock time
+ expire_entries()
+
+ # Increment frequency for this key
+ if op[0] == "get":
+ key = op[1]
+ else: # put
+ key = op[1]
+ increment_frequency(key)
+
+ # Process operation
+ if op[0] == "get":
+ handle_read(key)
+ else: # put
+ _, key, value, cost = op
+ handle_write(key, value, cost)
+
+ # Age frequencies if needed
+ if operation_count % reset_interval == 0:
+ for k in frequency:
+ frequency[k] = frequency[k] // 2
+
+# Build result
+final_probation = [[k, v[0]] for k, v in probation.items()]
+final_protected = [[k, v[0]] for k, v in protected.items()]
+total_weight = get_segment_weight(probation) + get_segment_weight(protected)
+
result = {
- "get_results": [],
- "final_probation": [],
- "final_protected": [],
- "total_weight": 0,
- "rejected": 0,
+ "get_results": get_results,
+ "final_probation": final_probation,
+ "final_protected": final_protected,
+ "total_weight": total_weight,
+ "rejected": rejected_count,
}
os.makedirs("output", exist_ok=True)
--- /dev/null
+++ b/output/result.json
@@ -0,0 +1 @@
+{"get_results": [100, 200, 100, 300, 100, 200, -1, 400, 100, 200, -1, 800, -1], "final_probation": [[2, 200]], "final_protected": [[1, 150], [8, 800]], "total_weight": 5, "rejected": 2}
Verifier output , the proof behind the reward
tests/test.sh
============================= test session starts ==============================
platform darwin -- Python 3.12.4, pytest-8.4.1, pluggy-1.6.0 -- /Library/Frameworks/Python.framework/Versions/3.12/bin/python3
cachedir: .pytest_cache
rootdir: <tmp>/workspace
plugins: anyio-4.12.1, respx-0.22.0, mock-3.15.1, asyncio-0.21.1
asyncio: mode=Mode.STRICT
collecting ... collected 13 items

tests/test_outputs.py::test_output_exists PASSED                         [  7%]
tests/test_outputs.py::test_shipped_input_correct PASSED                 [ 15%]
tests/test_outputs.py::test_shipped_exercises_the_gate PASSED            [ 23%]
tests/test_outputs.py::test_shipped_invariants PASSED                    [ 30%]
tests/test_outputs.py::test_hidden_inputs[3] PASSED                      [ 38%]
tests/test_outputs.py::test_hidden_inputs[4] PASSED                      [ 46%]
tests/test_outputs.py::test_hidden_inputs[8] PASSED                      [ 53%]
tests/test_outputs.py::test_hidden_inputs[11] PASSED                     [ 61%]
tests/test_outputs.py::test_hidden_inputs[13] PASSED                     [ 69%]
tests/test_outputs.py::test_hidden_inputs[16] PASSED                     [ 76%]
tests/test_outputs.py::test_hidden_inputs[33] PASSED                     [ 84%]
tests/test_outputs.py::test_hidden_inputs[47] PASSED                     [ 92%]
tests/test_outputs.py::test_hidden_inputs_are_nontrivial PASSED          [100%]

============================== 13 passed in 0.22s ==============================

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_c5c339442e00412d. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_c5c339442e00412d · verifier authoritative; classifier explanatory.