fix: bound model stream aggregation and close failed responses

apps/admin_console/services/request_diagnostics.py

@@ -66,6 +66,9 @@ def request_diagnostics(
                 "headers_at",
                 "first_output_at",
                 "last_output_at",
+                "first_tool_arguments_at",
+                "last_tool_arguments_at",
+                "cancel_observed_at",
                 "ended_at",
                 "retry_at",
             )

artemis/llm/argument_fingerprint.py

@@ -16,12 +16,38 @@ class ArgumentFingerprint:
         self.encoding_valid = True
         self.digest = hashlib.sha256()
         self.prefixes: list[dict] = []
+        self.whitespace_chars = 0
+        self.whitespace_run = 0
+        self.max_whitespace_run = 0
+        self.min_delta_chars: int | None = None
+        self.max_delta_chars = 0
+        self.same_delta_run = 0
+        self.max_same_delta_run = 0
+        self.previous_delta_digest: bytes | None = None
 
     def observe(self, arguments: str) -> None:
         self.characters += len(arguments)
         if not arguments:
             return
         self.deltas += 1
+        length = len(arguments)
+        self.min_delta_chars = min(self.min_delta_chars or length, length)
+        self.max_delta_chars = max(self.max_delta_chars, length)
+        for character in arguments:
+            if character in " \t\r\n":
+                self.whitespace_chars += 1
+                self.whitespace_run += 1
+                self.max_whitespace_run = max(self.max_whitespace_run, self.whitespace_run)
+            else:
+                self.whitespace_run = 0
+        # One digest, never the previous argument body. Surrogate handling here
+        # compares SDK strings only; wire UTF-8 fingerprints remain invalid below.
+        delta_digest = hashlib.sha256(arguments.encode("utf-8", "surrogatepass")).digest()
+        self.same_delta_run = (
+            self.same_delta_run + 1 if delta_digest == self.previous_delta_digest else 1
+        )
+        self.max_same_delta_run = max(self.max_same_delta_run, self.same_delta_run)
+        self.previous_delta_digest = delta_digest
         if not self.encoding_valid:
             return
         try:
@@ -50,4 +76,11 @@ class ArgumentFingerprint:
             "argument_deltas": self.deltas,
             "argument_prefixes": [dict(prefix) for prefix in self.prefixes],
             "argument_encoding_valid": self.encoding_valid,
+            "argument_json_whitespace_chars": self.whitespace_chars,
+            "argument_json_whitespace_run": self.whitespace_run,
+            "argument_json_whitespace_run_max": self.max_whitespace_run,
+            "argument_delta_chars_min": self.min_delta_chars,
+            "argument_delta_chars_max": self.max_delta_chars,
+            "argument_same_delta_run": self.same_delta_run,
+            "argument_same_delta_run_max": self.max_same_delta_run,
         }

artemis/llm/chunk_accumulator.py

@@ -0,0 +1,37 @@
+"""Amortize LangChain's partial-JSON parsing without buffering live UI output."""
+
+from langchain_core.messages import AIMessageChunk
+from langchain_core.messages.ai import add_ai_message_chunks
+
+CHUNK_BATCH_SIZE = 128
+
+
+class ChunkAccumulator:
+    def __init__(self):
+        self.response = None
+        self.pending = []
+
+    @property
+    def has_output(self):
+        return self.response is not None or bool(self.pending)
+
+    @property
+    def ready(self):
+        return len(self.pending) >= CHUNK_BATCH_SIZE
+
+    def append(self, chunk):
+        self.pending.append(chunk)
+
+    def flush(self):
+        chunks = ([self.response] if self.response is not None else []) + self.pending
+        if not chunks:
+            return None
+        if all(isinstance(chunk, AIMessageChunk) for chunk in chunks):
+            self.response = add_ai_message_chunks(chunks[0], *chunks[1:])
+        else:
+            result = chunks[0]
+            for chunk in chunks[1:]:
+                result = result + chunk
+            self.response = result
+        self.pending.clear()
+        return self.response

artemis/llm/diagnostics.py

@@ -1,6 +1,7 @@
 """Small, credential-free request snapshots in the existing task trace store."""
 
 import base64
+import asyncio
 from contextvars import ContextVar
 from copy import deepcopy
 import io
@@ -11,6 +12,8 @@ import time
 from uuid import uuid4
 
 from PIL import Image
+import httpx
+import httpx2
 
 from artemis.data_engine.context_vars import CURRENT_NODE_NAME, CURRENT_TRACE_ID
 from artemis.llm.argument_fingerprint import ArgumentFingerprint, MAX_TRACKED_TOOLS
@@ -20,6 +23,8 @@ from artemis.llm.usage import usage_from_message
 from artemis.llm.stream_guard import ToolArgumentOverflow
 from artemis.llm.response_guard import ResponseIntegrityError
 from artemis.runtime.cancellation import CancellationReason, cancellation_reason
+from artemis.llm.responses_diagnostics import ObservedResponseStream
+from artemis.llm.tool_constraints import request_constraints
 
 logger = logging.getLogger(__name__)
 ACTIVE_ATTEMPT: ContextVar["RequestAttempt | None"] = ContextVar("llm_attempt", default=None)
@@ -109,6 +114,7 @@ class RequestAttempt:
         self.last_publish = self.clock
         self.tools: dict[int | str, dict] = {}
         self.tool_fingerprints: dict[int | str, ArgumentFingerprint] = {}
+        self.wire_streams: list[ObservedResponseStream] = []
         self.review = ACTIVE_FINAL_REVIEW.get()
         if self.review:
             self.review.request_started(request_id, attempt)
@@ -138,6 +144,8 @@ class RequestAttempt:
         self.publish()
 
     def publish(self):
+        if self.wire_streams:
+            self.data["wire_responses"] = [s.observation.snapshot() for s in self.wire_streams]
         self.data["sequence"] += 1
         self.data["updated_at"] = time.time()
         self.data["elapsed_seconds"] = round(time.monotonic() - self.clock, 3)
@@ -168,6 +176,35 @@ class RequestAttempt:
         except (OSError, RuntimeError, ValueError, TypeError, AttributeError):
             logger.warning("Could not persist model request diagnostics", exc_info=True)
 
+    def publish_if_due(self):
+        if time.monotonic() - self.last_publish >= 5:
+            self.publish()
+
+    def stream_cancelled(self):
+        self.data.setdefault("cancel_observed_at", time.time())
+        self.data.setdefault("cancel_observed_phase", self.data["phase"])
+        self.data.setdefault("cancel_phase", self.data["phase"])
+
+    def stream_work(self, stage: str, elapsed: float):
+        stats = self.data.setdefault("stream_work", {}).setdefault(
+            stage, {"calls": 0, "total_seconds": 0.0, "max_seconds": 0.0}
+        )
+        stats["calls"] += 1
+        stats["total_seconds"] += elapsed
+        stats["max_seconds"] = max(stats["max_seconds"], elapsed)
+
+    async def close_streams(self):
+        try:
+            async with asyncio.timeout(1):
+                for stream in self.wire_streams:
+                    await stream.aclose()
+        except (TimeoutError, OSError, RuntimeError, httpx.HTTPError, httpx2.HTTPError) as error:
+            self.data["stream_close_error_type"] = type(error).__name__
+            logger.warning("Model stream cleanup failed: %s", type(error).__name__)
+        finally:
+            if self.wire_streams:
+                self.publish()
+
     def headers(self, response):
         self.data.update(
             headers_at=time.time(),
@@ -207,6 +244,9 @@ class RequestAttempt:
             arguments = tool.get("args")
             if isinstance(arguments, str):
                 self.data["tool_argument_chars"] += len(arguments)
+                if arguments:
+                    self.data.setdefault("first_tool_arguments_at", time.time())
+                    self.data["last_tool_arguments_at"] = time.time()
             index = tool.get("index")
             call_id = _identifier(tool.get("id"))
             key = index if index is not None else call_id or "unknown"
@@ -297,6 +337,7 @@ class RequestAttempt:
         self.publish()
 
     def cancel(self, error: BaseException | None = None):
+        self.stream_cancelled()
         reason = cancellation_reason(error)
         if self.review and self.review.expired and reason is CancellationReason.UNKNOWN:
             self.data["timeout_scope"] = "final_review"
@@ -321,6 +362,10 @@ async def observe_request_headers(request):
     attempt = ACTIVE_ATTEMPT.get()
     if attempt is None:
         return
+    try:
+        attempt.data["wire_request_constraints"] = request_constraints(request.content)
+    except (httpx.RequestNotRead, httpx2.RequestNotRead):
+        attempt.data["wire_request_constraints"] = {"observation": "streaming_body_unavailable"}
     request.headers.setdefault("X-Client-Request-Id", attempt.data["request_id"])
     request.headers.setdefault("X-Client-Attempt-Id", attempt.data["attempt_id"])
     routing = {}
@@ -342,7 +387,25 @@ async def observe_request_headers(request):
 
 
 async def observe_response_headers(response):
-    """httpx hook: only allowlisted headers, never body/auth/request headers."""
+    """Correlate allowlisted headers and passively observe bounded SSE frames."""
     attempt = ACTIVE_ATTEMPT.get()
     if attempt is not None:
         attempt.headers(response)
+        content_type = response.headers.get("content-type", "").split(";", 1)[0].lower()
+        if (
+            response.status_code == 200
+            and content_type == "text/event-stream"
+            and isinstance(response.stream, (httpx.AsyncByteStream, httpx2.AsyncByteStream))
+            and not isinstance(response.stream, ObservedResponseStream)
+        ):
+            if len(attempt.wire_streams) < 4:
+                stream = ObservedResponseStream(
+                    response.stream,
+                    attempt,
+                    encoded=response.headers.get("content-encoding", "identity").lower().strip()
+                    not in {"", "identity"},
+                )
+                response.stream = stream
+                attempt.wire_streams.append(stream)
+            else:
+                attempt.data["wire_streams_truncated"] = True

artemis/llm/responses_diagnostics.py

@@ -0,0 +1,301 @@
+"""Bounded observations at the client's raw SSE read boundary; never prefetch."""
+
+import asyncio
+import json
+import logging
+import re
+import time
+
+import httpx
+import httpx2
+
+from artemis.llm.argument_fingerprint import ArgumentFingerprint, MAX_TRACKED_TOOLS
+from artemis.llm.tool_constraints import safe_label, tool_constraints
+
+MAX_FRAME_BYTES = 256 * 1024
+MAX_RESPONSES = 16
+logger = logging.getLogger(__name__)
+
+
+def identifier(value):
+    return (
+        value
+        if isinstance(value, str) and re.fullmatch(r"[A-Za-z0-9_.:/-]{1,256}", value)
+        else None
+    )
+
+
+class ResponsesObservation:
+    def __init__(self, *, observe_sse=True):
+        self.observe_sse = observe_sse
+        self.data = {
+            "observation_boundary": "httpx_response_body_read",
+            "body_bytes": 0,
+            "sse_data_events": 0,
+            "parse_errors": 0,
+            "oversized_frames": 0,
+            "unknown_response_events": 0,
+            "statistics_truncated": False,
+            "body_eof_observed": False,
+        }
+        if not observe_sse:
+            self.data["sse_observation"] = "skipped_content_encoding"
+        self.responses: dict[str, dict] = {}
+        self.tools: dict[tuple, dict] = {}
+        self.fingerprints: dict[tuple, ArgumentFingerprint] = {}
+        self.aliases: dict[tuple, tuple] = {}
+        self.current_response: str | None = None
+        self.line = bytearray()
+        self.lines: list[bytes] = []
+        self.frame_bytes = 0
+        self.dropping = False
+        self.discarded_line = False
+
+    def feed(self, data: bytes):
+        self.data["body_bytes"] += len(data)
+        self.data["last_read_at"] = time.time()
+        self.data.setdefault("first_read_at", self.data["last_read_at"])
+        if not self.observe_sse:
+            return
+        offset = 0
+        while offset < len(data):
+            newline = data.find(b"\n", offset)
+            end = len(data) if newline < 0 else newline
+            size = end - offset
+            if self.dropping:
+                if size:
+                    if not self.discarded_line and not self.line and data[offset:end] == b"\r":
+                        self.line.extend(b"\r")
+                    else:
+                        self.discarded_line = True
+                        self.line.clear()
+            elif self.frame_bytes + len(self.line) + size + (newline >= 0) > MAX_FRAME_BYTES:
+                self.data["oversized_frames"] += 1
+                self.dropping = True
+                self.line.clear()
+                self.lines.clear()
+                self.discarded_line = True
+            elif not self.dropping:
+                self.line.extend(data[offset:end])
+            if newline < 0:
+                break
+            # When dropping, a blank physical line still ends the oversized frame.
+            if self.dropping:
+                if not self.discarded_line:
+                    self.dropping = False
+                    self.frame_bytes = 0
+                self.discarded_line = False
+                self.line.clear()
+            else:
+                line = bytes(self.line).removesuffix(b"\r")
+                self.frame_bytes += len(self.line) + 1
+                self.line.clear()
+                if not line:
+                    self._frame()
+                    self.lines.clear()
+                    self.frame_bytes = 0
+                elif line.startswith(b"data:"):
+                    self.lines.append(line[5:].removeprefix(b" "))
+            offset = newline + 1
+
+    def _frame(self):
+        if not self.lines:
+            return
+        self.data["sse_data_events"] += 1
+        body = b"\n".join(self.lines)
+        if body == b"[DONE]":
+            self.data["sse_done_events"] = self.data.get("sse_done_events", 0) + 1
+            return
+        try:
+            event = json.loads(body)
+        except (ValueError, UnicodeError, RecursionError):
+            self.data["parse_errors"] += 1
+            return
+        if not isinstance(event, dict):
+            self.data["parse_errors"] += 1
+            return
+        self.event(event)
+
+    def event(self, event: dict):
+        kind = event.get("type")
+        kind = kind if isinstance(kind, str) else None
+        response = event.get("response")
+        response = response if isinstance(response, dict) else {}
+        response_id = identifier(event.get("response_id")) or identifier(response.get("id"))
+        if response_id:
+            self.current_response = response_id
+        response_id = self.current_response
+        if response_id is None:
+            self.data["unknown_response_events"] += 1
+            return
+        if response_id not in self.responses and len(self.responses) >= MAX_RESPONSES:
+            self.data["statistics_truncated"] = True
+            return
+        stats = self.responses.setdefault(
+            response_id,
+            {
+                "response_id": response_id,
+                "events": 0,
+                "sequence_missing_events": 0,
+                "sequence_forward_gaps": 0,
+                "sequence_forward_missing_total": 0,
+                "sequence_non_increasing": 0,
+                "sequence_equal_previous": 0,
+            },
+        )
+        stats["events"] += 1
+        sequence = event.get("sequence_number")
+        if type(sequence) is int and sequence >= 0:
+            previous = stats.get("sequence_last")
+            if previous is not None:
+                if sequence <= previous:
+                    stats["sequence_non_increasing"] += 1
+                    stats["sequence_equal_previous"] += int(sequence == previous)
+                elif sequence > previous + 1:
+                    stats["sequence_forward_gaps"] += 1
+                    stats["sequence_forward_missing_total"] += sequence - previous - 1
+            stats.setdefault("sequence_first", sequence)
+            stats["sequence_last"] = sequence
+        else:
+            stats["sequence_missing_events"] += 1
+        if kind in {
+            "response.completed",
+            "response.failed",
+            "response.incomplete",
+            "response.cancelled",
+        }:
+            stats["terminal_event"] = kind
+        if "tools" in response:
+            stats["returned_tool_constraints"] = tool_constraints(response["tools"])
+        if "max_output_tokens" in response:
+            limit = response["max_output_tokens"]
+            stats["returned_max_output_tokens"] = limit if type(limit) is int else None
+        self._tool(event, response_id)
+
+    def _tool(self, event, response_id):
+        kind = event.get("type")
+        if not isinstance(kind, str):
+            return
+        item = event.get("item")
+        item = item if isinstance(item, dict) else {}
+        if kind in {"response.output_item.added", "response.output_item.done"}:
+            if item.get("type") != "function_call":
+                return
+        elif kind not in {
+            "response.function_call_arguments.delta",
+            "response.function_call_arguments.done",
+        }:
+            return
+        item_id = identifier(event.get("item_id")) or identifier(item.get("id"))
+        index = event.get("output_index")
+        index = index if type(index) is int and index >= 0 else None
+        alias = (response_id, index)
+        key = self.aliases.get(alias) if index is not None else None
+        key = key or (response_id, item_id if item_id else index)
+        if key not in self.tools and len(self.tools) >= MAX_TRACKED_TOOLS:
+            self.data["statistics_truncated"] = True
+            return
+        if index is not None:
+            if alias in self.aliases or len(self.aliases) < 2 * MAX_TRACKED_TOOLS:
+                self.aliases[alias] = key
+            else:
+                self.data["statistics_truncated"] = True
+        stats = self.tools.setdefault(key, {"response_id": response_id, "delta_events": 0})
+        if not item_id and index is None:
+            stats["identity_unknown"] = True
+        if item_id and stats.get("item_id") not in (None, item_id):
+            stats["identity_conflicts"] = stats.get("identity_conflicts", 0) + 1
+        if item_id:
+            stats["item_id"] = item_id
+        if (call_id := identifier(item.get("call_id"))) is not None:
+            stats["call_id"] = call_id
+        if (name := safe_label(item.get("name"))) is not None:
+            stats["name"] = name
+        if index is not None:
+            stats["output_index"] = index
+        fingerprint = self.fingerprints.get(key)
+        if fingerprint is None:
+            fingerprint = self.fingerprints[key] = ArgumentFingerprint()
+        arguments = None
+        if kind == "response.function_call_arguments.delta":
+            stats["delta_events"] += 1
+            arguments = event.get("delta")
+        elif kind == "response.output_item.added":
+            arguments = item.get("arguments")
+        elif kind == "response.function_call_arguments.done":
+            stats["arguments_done_events"] = stats.get("arguments_done_events", 0) + 1
+        elif kind == "response.output_item.done":
+            stats["output_item_done_events"] = stats.get("output_item_done_events", 0) + 1
+        if isinstance(arguments, str):
+            fingerprint.observe(arguments)
+            if arguments:
+                stats.setdefault("first_argument_at", time.time())
+                stats["last_argument_at"] = time.time()
+
+    def end(self, *, eof=False):
+        self.data["body_eof_observed"] = self.data["body_eof_observed"] or eof
+        self.data["incomplete_sse_frame"] = self.data.get("incomplete_sse_frame", False) or bool(
+            self.line or self.lines or self.dropping
+        )
+        self.line.clear()
+        self.lines.clear()
+
+    def snapshot(self):
+        return {
+            **self.data,
+            "responses": [dict(r) for r in self.responses.values()],
+            "tools": [{**r, **self.fingerprints[k].snapshot()} for k, r in self.tools.items()],
+        }
+
+
+class ObservedResponseStream(httpx.AsyncByteStream, httpx2.AsyncByteStream):
+    def __init__(
+        self, stream: httpx.AsyncByteStream | httpx2.AsyncByteStream, attempt, *, encoded=False
+    ):
+        self.stream = stream
+        self.attempt = attempt
+        self.observation = ResponsesObservation(observe_sse=not encoded)
+        self.closed = False
+        self.close_attempted = False
+
+    async def __aiter__(self):
+        try:
+            async for data in self.stream:
+                started = time.monotonic()
+                self.observation.feed(data)
+                self.attempt.stream_work("wire_observe", time.monotonic() - started)
+                self.attempt.publish_if_due()
+                yield data
+            self.observation.end(eof=True)
+        except asyncio.CancelledError:
+            self.attempt.stream_cancelled()
+            raise
+
+    async def aclose(self):
+        if self.close_attempted:
+            return
+        self.close_attempted = True
+        stats = self.observation.data
+        stats.setdefault("close_started_at", time.time())
+        try:
+            async with asyncio.timeout(1):
+                await self.stream.aclose()
+        except TimeoutError:
+            # A cleanup deadline must not replace an in-flight user stop with
+            # a retryable model timeout. Failure remains explicit in diagnostics.
+            stats["close_error_type"] = "TimeoutError"
+            logger.warning("Model HTTP stream close exceeded its cleanup deadline")
+        except (
+            asyncio.CancelledError,
+            OSError,
+            RuntimeError,
+            httpx.HTTPError,
+            httpx2.HTTPError,
+        ) as error:
+            stats["close_error_type"] = type(error).__name__
+            raise
+        else:
+            self.closed = True
+            stats["closed_at"] = time.time()
+        finally:
+            self.observation.end(eof=stats["body_eof_observed"])

artemis/llm/tool_constraints.py

@@ -0,0 +1,109 @@
+"""Summarize actual wire tool constraints without persisting schemas or prompts."""
+
+import hashlib
+import json
+import re
+
+from artemis.llm.argument_fingerprint import MAX_TRACKED_TOOLS
+
+MAX_REQUEST_BYTES = 4 * 1024 * 1024
+
+
+def safe_label(value):
+    return value if isinstance(value, str) and re.fullmatch(r"[\w.:-]{1,128}", value) else None
+
+
+def strict_state(tool: dict) -> str:
+    if "strict" not in tool:
+        return "omitted"
+    if tool["strict"] is True:
+        return "true"
+    if tool["strict"] is False:
+        return "false"
+    return "invalid"
+
+
+def schema_summary(schema: dict) -> dict:
+    """Count syntactic schema nodes, not expanded $refs or arbitrary examples."""
+    result = {"objects": 0, "optional_properties": 0, "open_objects": 0, "nodes": 0}
+    pending = [schema]
+    while pending and result["nodes"] < 1024:
+        node = pending.pop()
+        result["nodes"] += 1
+        properties = node.get("properties")
+        if node.get("type") == "object" or isinstance(properties, dict):
+            result["objects"] += 1
+            required = node.get("required")
+            required = required if isinstance(required, list) else []
+            if isinstance(properties, dict):
+                result["optional_properties"] += sum(k not in required for k in properties)
+            if node.get("additionalProperties") is not False:
+                result["open_objects"] += 1
+        children = []
+        for key in ("properties", "$defs", "definitions"):
+            if isinstance(node.get(key), dict):
+                children.extend(node[key].values())
+        for key in ("anyOf", "oneOf", "allOf", "prefixItems"):
+            if isinstance(node.get(key), list):
+                children.extend(node[key])
+        children.extend(node.get(k) for k in ("items", "additionalProperties", "not"))
+        remaining = max(0, 1024 - result["nodes"] - len(pending))
+        eligible = [v for v in children if isinstance(v, dict)]
+        if len(eligible) > remaining:
+            result["truncated"] = True
+        pending.extend(eligible[:remaining])
+    result["truncated"] = bool(pending) or result.get("truncated", False)
+    try:
+        result["sha256"] = hashlib.sha256(
+            json.dumps(schema, sort_keys=True, separators=(",", ":"), ensure_ascii=True).encode()
+        ).hexdigest()
+    except (RecursionError, TypeError, ValueError):
+        result["sha256"] = None
+        result["truncated"] = True
+    return result
+
+
+def tool_constraints(tools) -> dict:
+    records = []
+    pending = tools[:MAX_TRACKED_TOOLS] if isinstance(tools, list) else []
+    truncated = isinstance(tools, list) and len(tools) > MAX_TRACKED_TOOLS
+    visited = 0
+    while pending and visited < MAX_TRACKED_TOOLS:
+        tool = pending.pop(0)
+        visited += 1
+        if not isinstance(tool, dict):
+            continue
+        if tool.get("type") == "namespace":
+            nested = tool.get("tools")
+            if isinstance(nested, list):
+                remaining = MAX_TRACKED_TOOLS - len(pending) - visited
+                truncated = truncated or len(nested) > remaining
+                pending.extend(nested[:remaining])
+            continue
+        function = tool.get("function", tool)
+        if not isinstance(function, dict):
+            continue
+        record = {
+            "type": safe_label(tool.get("type")),
+            "name": safe_label(function.get("name")),
+            "strict": strict_state(function),
+        }
+        if isinstance(function.get("parameters"), dict):
+            record["schema"] = schema_summary(function["parameters"])
+        records.append(record)
+    return {"tools": records, "truncated": truncated or bool(pending), "observation": "available"}
+
+
+def request_constraints(body: bytes) -> dict:
+    if len(body) > MAX_REQUEST_BYTES:
+        return {"observation": "body_too_large"}
+    try:
+        payload = json.loads(body)
+    except (ValueError, UnicodeError, RecursionError):
+        return {"observation": "invalid_json"}
+    if not isinstance(payload, dict):
+        return {"observation": "not_an_object"}
+    result = tool_constraints(payload.get("tools"))
+    limit = payload.get("max_output_tokens")
+    result["max_output_tokens"] = limit if type(limit) is int and limit > 0 else None
+    return result

artemis/services/llm.py

@@ -47,6 +47,7 @@ from artemis.config import (
 from artemis.context import ArtemisContext
 from artemis.data_engine.trace import CURRENT_TRACE_ID, DataEngineCallbackHandler
 from artemis.llm.diagnostics import ACTIVE_ATTEMPT, RequestAttempt, error_text, input_images
+from artemis.llm.chunk_accumulator import ChunkAccumulator
 from artemis.llm.final_review import (
     ACTIVE_FINAL_REVIEW,
     FinalReviewBudget,
@@ -425,8 +426,13 @@ async def _run_with_recovery[T](
                 observation_token = ACTIVE_ATTEMPT.set(observation)
                 request_timer = asyncio.timeout(timeout)
                 try:
-                    async with request_timer:
+                    try:
-                        result = await call_once()
+                        async with request_timer:
+                            result = await call_once()
+                    finally:
+                        # Release a failed stream before any retry backoff, even
+                        # when the SDK consumer stopped between yielded chunks.
+                        await observation.close_streams()
                 except (KeyboardInterrupt, asyncio.CancelledError) as e:
                     observation.cancel(e)
                     raise
@@ -818,24 +824,46 @@ class RobustChatModelWrapper:
 
         stream_exec_id = uuid4()
         full_response = None
+        accumulator = ChunkAccumulator()
         argument_guard = ToolArgumentGuard()
         try:
             async with aclosing(self.base_model.astream(*args, **kwargs)) as stream:
+                wait_started = time.monotonic()
                 async for chunk in stream:
                     observation = ACTIVE_ATTEMPT.get()
                     if observation is not None:
+                        observation.stream_work("await_sdk_chunk", time.monotonic() - wait_started)
+                        observe_started = time.monotonic()
                         observation.chunk(chunk)
+                        observation.stream_work("sdk_observe", time.monotonic() - observe_started)
                     argument_guard.observe(chunk)
-                    if full_response is None:
+                    accumulator.append(chunk)
-                        full_response = chunk
+                    if accumulator.ready:
-                    else:
+                        # Buffered transport input may yield without suspending.
-                        full_response = full_response + chunk
+                        # Give stop/deadline signals a turn before a batch merge.
+                        await asyncio.sleep(0)
+                        merge_started = time.monotonic()
+                        full_response = accumulator.flush()
+                        if observation is not None:
+                            observation.stream_work("merge", time.monotonic() - merge_started)
                     if emit_deltas:
+                        emit_started = time.monotonic()
                         self._emit_stream_delta(stream_exec_id, chunk)
+                        if observation is not None:
+                            observation.stream_work("emit", time.monotonic() - emit_started)
+                    wait_started = time.monotonic()
+            merge_started = time.monotonic()
+            full_response = accumulator.flush()
+            observation = ACTIVE_ATTEMPT.get()
+            if observation is not None:
+                observation.stream_work("merge", time.monotonic() - merge_started)
             if full_response is not None:
                 ensure_response_complete(full_response)
         except (KeyboardInterrupt, asyncio.CancelledError):
-            if full_response is not None:
+            observation = ACTIVE_ATTEMPT.get()
+            if observation is not None:
+                observation.stream_cancelled()
+            if accumulator.has_output:
                 _record_llm_event(
                     "llm_stream_reset",
                     {
@@ -847,7 +875,7 @@ class RobustChatModelWrapper:
                 )
             raise
         except Exception as stream_error:
-            if full_response is not None or isinstance(
+            if accumulator.has_output or isinstance(
                 stream_error, (ToolArgumentOverflow, ResponseIntegrityError)
             ):
                 if isinstance(stream_error, ResponseIntegrityError):

docs/llm-stream-diagnostics.md

@@ -2,6 +2,8 @@
 
 小型内置动作的参数流仍受 16384 字符保护。超限时关闭输出流、丢弃不完整参数，不执行该次动作；一次新响应重试和可用备用端点耗尽后，只结束当前任务，不进入共享的模型暂停。批次仍遵循“失败即停止”、人工暂停和取消设置。网络故障、认证错误和最终验收保留各自的恢复规则。
 
+长度保护不是生成进度判断：小于上限但一直没有闭合或终止的参数，仍可能持续到单次请求或外层任务超时。超时、取消和完整性校验共同约束这条路径，未完成的参数不能作为动作执行。
+
 ## 请求关联
 
 每个模型请求尝试沿用现有 `llm_diagnostic` 记录，不另建日志数据库。
@@ -27,6 +29,9 @@
 - `argument_deltas`：非空参数片段数，不能直接与网关原始事件数比较。
 - `argument_prefixes`：每 4096 字节的累计 SHA256，最多保留前 16 个。可以在分片大小不同、上游预读或中途取消时比较相同字节位置。
 - `argument_encoding_valid`：遇到不能编码为 UTF-8 的片段时为 false，当前总字节数和总哈希留空，避免伪造可比结果；诊断本身不改变执行流程。
+- `argument_json_whitespace_chars` / `argument_json_whitespace_run` / `argument_json_whitespace_run_max`：实际空格、制表、回车和换行字符的总数、当前尾部连续数和最长连续数。统计的是这四种 JSON 空白码点，也包含字符串内部的实际字符；转义文本 `\\n`、不换行空格不计入。不据此判断 JSON 是否有效。
+- `argument_delta_chars_min` / `argument_delta_chars_max`：非空参数增量的最小、最大字符数；尚无非空增量时最小值为空。
+- `argument_same_delta_run` / `argument_same_delta_run_max`：连续相同非空增量的当前、最长出现次数，首个增量算一次，空增量不打断。只保留上一增量的 SHA256，不保留正文。相同增量内容不等于重复的协议事件，例如连续空格也可能来自不同的合法事件。
 
 最多记录 64 个工具；超过时设置 `tool_stats_truncated=true`，总参数字符计数仍继续。诊断不保留参数正文。哈希仅证明已收到的字节前缀，不能证明输出完整或动作成功；完整性仍由响应终止状态和解析校验决定。
 
@@ -34,6 +39,38 @@
 
 历史日志没有保存的原始帧无法由新增诊断恢复。HTTP 200 只说明响应头已到达；客户端保护后出现的 499 或 Broken pipe 也不能证明最初原因。网关写入本机下游 writer 成功不等于客户端已消费或执行。
 
+## 客户端原始 Responses 观测
+
+`wire_responses` 被动观察 HTTP 客户端实际读取的 SSE 字节，在 SDK 转换之前统计。同一网络读取中可能包含多个事件，因此原始统计可以领先 SDK；SDK 回调阻塞也会扩大两者差距。这一边界不是服务器写出时刻，也不是工具执行时刻。诊断不增加预读任务、队列或重传，不过滤、改写交给 SDK 的字节。
+
+每个响应记录 `response_id`、事件数及 `sequence_number` 的首末值。`sequence_forward_gaps` / `sequence_forward_missing_total` 统计相邻观测间的向前跳变次数及跳过的序号数；乱序事件可能随后补上，不能直接称为永久丢包。`sequence_non_increasing` 统计非递增，`sequence_equal_previous` 统计与前一个序号相等。`sequence_missing_events` 表示事件本身没有有效序号，不表示传输丢失。没有响应编号时不猜测，记录 `unknown_response_events`；标准流中没有编号的后续事件沿用当前响应编号。
+
+每个函数调用记录与 SDK 相同的参数指纹和形态统计，另记原始 `delta_events`、首末参数到达时间，以及两类 done 事件的次数。只累计非空初始 arguments 和 arguments.delta，不重复累计 done 的完整快照。关联优先使用响应编号与实际 `call_id`，`item_id` / `output_index` 用于同一原始流内关联；`identity_unknown`、`identity_conflicts` 表明身份不足或冲突，此时不能据此归责。
+
+每次尝试最多观察 4 条 HTTP 流；每条流最多 16 个响应、64 个工具、128 个索引别名，每工具最多 16 个固定前缀。单个待解析 SSE 帧最多 256KiB，超出后仅跳过该帧的诊断，继续原样交给 SDK。`oversized_frames`、`parse_errors`、`statistics_truncated`、`wire_streams_truncated` 说明覆盖缺口；`incomplete_sse_frame` 与 `body_eof_observed` 区分未闭合帧和正常字节流结束。待解析字节仅临时保留，关闭时释放，日志不保存帧或参数正文。
+
+原始分帧支持 LF / CRLF。HTTP 体声明 gzip 等压缩编码时，标记 `sse_observation=skipped_content_encoding`，只统计读取字节与时间，不把压缩字节误当成 SSE；SDK 仍按原路径解压。这种记录缺少原始事件统计，不能把零计数当成没有收到参数。
+
+## 实际工具约束与耗时
+
+`wire_request_constraints` 检查 HTTP 请求已经序列化的正文，不记录提示、图片或 Schema 正文。逐工具记录 `strict` 为 `omitted`、`false`、`true`，异常值为 `invalid`；不能把省略当成 false，更不能把 Pydantic 本地严格校验当成上游约束。Schema 只保存 SHA256、对象数、非 required 的属性数及未关闭对象数。这是语法统计，不展开引用，也不是上游 Schema 兼容性验证。
+
+当前 `click`、`action_sequence`、`drag` 的真实 SDK 离线请求均省略 strict，保留可选字段。不能只把 strict 开关改为 true：应先按目标接口支持的 Schema 子集处理对象和 required，保留可选值的 nullable 语义，再单独验证兼容性。
+
+请求正文超过 4MiB 时跳过检查并记录 `body_too_large`；流式上传正文不可直接读取时记录 `streaming_body_unavailable`，不会为了诊断消费上传流。最多检查 64 个工具或命名空间节点，每个 Schema 最多统计 1024 个节点，达到上限标记截断。响应事件如果回传 tools，则保存同样的 `returned_tool_constraints`；回显不证明服务端实际执行了约束。
+
+`max_output_tokens` 与 `returned_max_output_tokens` 只表示本层实际观察到的字段。本次核对的 CodexManager 通道会过滤输出 token 上限；短合成探针成功也不能证明上限被执行。不能把设置 max_tokens / max_output_tokens 当成这条链路可靠的止损办法，客户端长度、超时和取消保护仍然必要。
+
+`stream_work` 记录每阶段的调用次数、总耗时和最长耗时：`wire_observe` 为原始帧诊断，`sdk_observe` 为 SDK 片段诊断，`merge` 为聚合，`emit` 为界面回调，`await_sdk_chunk` 为等待 SDK 交出下一个片段。最后一项包含网络读取、原始观测、SDK 转换和 SDK 回调等工作，与其他阶段可能重叠，不能相加或直接当成网络延迟。
+
+聚合每 128 个片段合并一次，降低 SDK 反复解析半截 JSON 的开销；长度保护、诊断和界面输出仍逐片段执行，异步压缩继续使用原异步调用路径。分批合并不修复参数 JSON，最终仍须经过完整性和严格解析校验。
+
+## 取消与关闭
+
+`cancel_observed_at` / `cancel_observed_phase` 记录本次尝试首次在客户端观测到取消的时间与阶段，不等于用户点击停止的时间。`cancel_phase` / `cancel_reason` 沿用恢复层最终记录的取消阶段和来源，可能反映后续重试等待中的停止。首末 SDK 参数时间为 `first_tool_arguments_at` / `last_tool_arguments_at`。原始流内的读取、参数和关闭时间采用 Unix 秒。
+
+SDK 读取中、回调中或两次 yield 之间触发长度保护后，尝试结束路径都会主动关闭已观察的 HTTP 流，不等待垃圾回收。`close_started_at` 记录关闭开始，只有实际成功才写 `closed_at`；失败只记录异常类型，关闭等待最多 1 秒。关闭超时不能覆盖用户停止而变成可重试的请求超时。未能关闭时保留错误证据，不声称连接已成功释放。
+
 ## 已核对的上游异常样本（2026-11-02）
 
 一次真实 `action_sequence` 调用在任务超时前持续接收参数，没有完成该工具调用。该样本发生在 `action_sequence` 纳入参数保护之前。按同一 `response_id + call_id` 核对生产诊断，得到以下字符数；请求编号和设备信息不在文档中保留：
@@ -48,10 +85,14 @@
 
 五个边界在 4096 到 36864 字节的九个累计 SHA256 上一致。NewAPI 使用透传模式，收到和写出的完整参数哈希也一致。上游没有终止事件，也没有完成参数快照。该样本证明参数在官方上游返回时就已持续增长，不能归因于 NewAPI 转换、下游重复累计完成快照或 ARTEMIS 最终消息拼接。取消、预读和缓冲会使各层停止计数的位置不同；尾部总长度不同本身不能证明重复发送或字符丢失。
 
-诊断没有参数正文，不能进一步断言是空白循环、重复描述或官方服务内部的重复事件。这个定位也不能追溯证明没有原始诊断的历史事故。另一次 `click` 异常同样在 NewAPI 接收时已超过四万字符，说明这种现象并非新动作序列独有。
+诊断没有参数正文，不能进一步断言是模型生成循环、空白循环、重复描述或官方服务内部的重复事件，也不能排除请求结构触发异常。这个定位只排除已核对样本的下游放大作为最初来源，不能追溯证明没有原始诊断的历史事故。另一次 `click` 异常同样在 NewAPI 接收时已超过四万字符，说明这种现象并非新动作序列独有。
+
+CodexManager 另行修正了普通函数放入 functions 命名空间的兼容性问题。其短上下文、低思考强度合成测试通过，仅能作为兼容性对照，尚不能代替原事故的长上下文、多图、高思考强度复现，也不能称为参数膨胀的根因修复。
 
 本地保护覆盖 `action_sequence`、`drag` 及其他小型内置动作：超限后关闭流、丢弃参数，并按既有策略有限重试；它限制异常对当前任务的影响，不修复上游生成行为，也不保证业务任务一定成功。缩放面板自动隐藏导致的定位失败由动作序列的 `ensure_visible` 准备步骤处理，与参数流异常分别诊断。
 
 ## 离线验证
 
 `tests/unit/test_llm_stream_guard.py` 验证保护、有限重试、相同/不同备用端点，以及不会创建或清除其他请求的全局暂停。`tests/unit/test_request_diagnostics.py` 验证请求编号、超时重试、响应头及单次参数计数。`tests/unit/test_argument_fingerprint.py` 验证不同分片、中文和 emoji、固定字节前缀、有界统计与异常编码。这些测试不调用真实模型或设备。
+
+`tests/unit/test_responses_diagnostics.py` 验证原始分帧、序号、done 去重、有界统计和 strict 三态。`tests/unit/test_responses_wire_lifecycle.py` 使用已安装的真实 OpenAI/LangChain SDK 与内存 HTTP 传输，验证小于长度阈值的未闭合流、SDK 回调背压、请求/任务超时、用户停止、超限后主动关闭和关闭失败，以及实际工具 Schema；不发网络请求。`tests/unit/test_chunk_accumulator.py` 对比逐片段聚合结果，验证交错工具、元数据和使用量保持一致，减少半截 JSON 重复解析，异常参数仍由最终校验拒绝。离线通过不代表原业务任务的稳定性已验收。

tests/unit/test_argument_fingerprint.py

@@ -33,7 +33,7 @@ def test_invalid_utf8_is_marked_without_failing_or_forging_a_digest():
     fingerprint = ArgumentFingerprint()
     for value in ["safe", "\ud800", "later"]:
         fingerprint.observe(value)
-    assert fingerprint.snapshot() == {
+    expected = {
         "argument_chars": 10,
         "argument_bytes": None,
         "argument_sha256": None,
@@ -41,6 +41,24 @@ def test_invalid_utf8_is_marked_without_failing_or_forging_a_digest():
         "argument_prefixes": [],
         "argument_encoding_valid": False,
     }
+    assert {key: fingerprint.snapshot()[key] for key in expected} == expected
+
+
+def test_shape_counts_cross_delta_whitespace_and_repetition_without_retaining_text():
+    fingerprint = ArgumentFingerprint()
+    for fragment in ['{"text":"private', " ", " \t", "", " \t", " \t", '\u00a0"}']:
+        fingerprint.observe(fragment)
+    stats = fingerprint.snapshot()
+    assert stats["argument_json_whitespace_chars"] == 7
+    assert stats["argument_json_whitespace_run_max"] == 7
+    assert stats["argument_json_whitespace_run"] == 0
+    assert stats["argument_delta_chars_min"] == 1
+    assert stats["argument_delta_chars_max"] == len('{"text":"private')
+    assert stats["argument_same_delta_run_max"] == 3
+    assert stats["argument_same_delta_run"] == 1
+    assert stats["argument_deltas"] == 6
+    assert "private" not in repr(vars(fingerprint))
+    assert "private" not in json.dumps(stats)
 
 
 def test_tool_tracking_is_bounded_but_total_count_keeps_all_received_arguments():

tests/unit/test_chunk_accumulator.py

@@ -0,0 +1,83 @@
+import itertools
+import json
+
+from langchain_core.messages import AIMessageChunk
+import langchain_core.messages.ai as ai
+import pytest
+
+from artemis.llm.chunk_accumulator import ChunkAccumulator
+from artemis.llm.response_guard import ResponseIntegrityError, ensure_response_complete
+
+
+def test_batching_preserves_interleaved_tools_unicode_metadata_and_usage():
+    arguments = [json.dumps({"target": "中文🙂" * 80}), json.dumps({"target": 3})]
+    chunks = [AIMessageChunk(content="Live text", id="resp_one")]
+    for index in range(2):
+        chunks.append(
+            AIMessageChunk(
+                content=[],
+                tool_call_chunks=[
+                    {"name": "click", "args": "", "id": f"call_{index}", "index": index}
+                ],
+            )
+        )
+    for pair in itertools.zip_longest(*arguments):
+        for index, value in enumerate(pair):
+            if value is not None:
+                chunks.append(
+                    AIMessageChunk(content=[], tool_call_chunks=[{"args": value, "index": index}])
+                )
+    chunks.append(
+        AIMessageChunk(
+            content=[],
+            response_metadata={"id": "resp_one", "status": "completed"},
+            usage_metadata={"input_tokens": 10, "output_tokens": 5, "total_tokens": 15},
+            chunk_position="last",
+        )
+    )
+    expected = chunks[0]
+    accumulator = ChunkAccumulator()
+    max_pending = 0
+    for index, chunk in enumerate(chunks):
+        if index:
+            expected = expected + chunk
+        accumulator.append(chunk)
+        if accumulator.ready:
+            accumulator.flush()
+        max_pending = max(max_pending, len(accumulator.pending))
+    result = accumulator.flush()
+    assert result.model_dump() == expected.model_dump()
+    assert [t["args"] for t in result.tool_calls] == [json.loads(a) for a in arguments]
+    assert result.usage_metadata["total_tokens"] == 15
+    assert max_pending < 256
+    assert not accumulator.pending
+
+
+def test_partial_json_is_not_reparsed_for_every_single_character(monkeypatch):
+    chunks = [
+        AIMessageChunk(
+            content=[], tool_call_chunks=[{"name": "click", "args": '{"target":x', "index": 0}]
+        )
+    ]
+    chunks.extend(
+        AIMessageChunk(content=[], tool_call_chunks=[{"args": "x", "index": 0}]) for _ in range(800)
+    )
+    original = ai.parse_partial_json
+    parsed_lengths = []
+
+    def counted(arguments, *args, **kwargs):
+        parsed_lengths.append(len(arguments))
+        return original(arguments, *args, **kwargs)
+
+    monkeypatch.setattr(ai, "parse_partial_json", counted)
+    accumulator = ChunkAccumulator()
+    for chunk in chunks:
+        accumulator.append(chunk)
+        if accumulator.ready:
+            accumulator.flush()
+    result = accumulator.flush()
+    assert result.tool_call_chunks[0]["args"] == '{"target":x' + "x" * 800
+    assert len(parsed_lengths) < 20
+    result.response_metadata["status"] = "completed"
+    with pytest.raises(ResponseIntegrityError):
+        ensure_response_complete(result)

tests/unit/test_request_diagnostics.py

@@ -226,7 +226,7 @@ def test_tool_deltas_are_counted_once_without_retaining_arguments():
         [2, 1],
         strict=True,
     ):
-        assert tool == {
+        expected = {
             "name": name,
             "call_id": call_id,
             "chunk_index": index,
@@ -237,6 +237,7 @@ def test_tool_deltas_are_counted_once_without_retaining_arguments():
             "argument_prefixes": [],
             "argument_encoding_valid": True,
         }
+        assert {key: tool[key] for key in expected} == expected
     assert attempt.data["response_status"] == "completed"
     assert "private" not in json.dumps(engine.records, default=str)
     assert "secret" not in json.dumps(engine.records, default=str)

tests/unit/test_responses_diagnostics.py

@@ -0,0 +1,263 @@
+import json
+import gzip
+from types import SimpleNamespace
+
+import httpx2
+import pytest
+
+from artemis.llm.responses_diagnostics import MAX_FRAME_BYTES, ResponsesObservation
+from artemis.llm.diagnostics import ACTIVE_ATTEMPT, observe_response_headers
+from artemis.llm.tool_constraints import MAX_REQUEST_BYTES, request_constraints, tool_constraints
+
+
+def frame(kind, sequence, **fields):
+    return (
+        "data: "
+        + json.dumps({"type": kind, "sequence_number": sequence, **fields}, ensure_ascii=False)
+        + "\r\n\r\n"
+    ).encode()
+
+
+@pytest.mark.parametrize("size", [1, 37, 100000])
+def test_raw_frames_split_unicode_and_done_snapshots_are_not_double_counted(size):
+    arguments = '{"text":"私人🙂"}'
+    data = b"".join(
+        [
+            frame("response.created", 0, response={"id": "resp_one"}),
+            frame(
+                "response.output_item.added",
+                1,
+                output_index=2,
+                item={
+                    "type": "function_call",
+                    "id": "fc_one",
+                    "call_id": "call_one",
+                    "name": "click",
+                    "arguments": "",
+                },
+            ),
+            frame(
+                "response.function_call_arguments.delta",
+                2,
+                output_index=2,
+                item_id="fc_one",
+                delta=arguments,
+            ),
+            frame(
+                "response.function_call_arguments.done",
+                3,
+                output_index=2,
+                item_id="fc_one",
+                arguments=arguments,
+            ),
+            frame(
+                "response.output_item.done",
+                4,
+                output_index=2,
+                item={"type": "function_call", "id": "fc_one", "arguments": arguments},
+            ),
+            frame(
+                "response.completed",
+                5,
+                response={
+                    "id": "resp_one",
+                    "tools": [{"type": "function", "name": "click", "strict": True}],
+                },
+            ),
+        ]
+    )
+    observer = ResponsesObservation()
+    for offset in range(0, len(data), size):
+        observer.feed(data[offset : offset + size])
+    observer.end(eof=True)
+    stats = observer.snapshot()
+    assert stats["body_bytes"] == len(data)
+    assert stats["parse_errors"] == 0
+    assert stats["incomplete_sse_frame"] is False
+    (tool,) = stats["tools"]
+    assert tool["argument_chars"] == len(arguments)
+    assert (
+        tool["delta_events"]
+        == tool["arguments_done_events"]
+        == tool["output_item_done_events"]
+        == 1
+    )
+    assert tool["call_id"] == "call_one"
+    (response,) = stats["responses"]
+    assert response["sequence_first"] == 0 and response["sequence_last"] == 5
+    assert response["sequence_forward_gaps"] == response["sequence_non_increasing"] == 0
+    assert response["returned_tool_constraints"]["tools"][0]["strict"] == "true"
+    assert "私人" not in json.dumps(stats, ensure_ascii=False)
+    assert not observer.line and not observer.lines
+
+
+def test_sequence_statistics_are_per_response_and_describe_observed_jumps():
+    observer = ResponsesObservation()
+    observer.event({"type": "response.in_progress", "sequence_number": 1})
+    observer.event({"type": "response.created", "sequence_number": 0, "response": {"id": "resp_a"}})
+    for seq in [2, 2, 1, 3, None]:
+        observer.event({"type": "response.in_progress", "sequence_number": seq})
+    observer.event({"type": "response.created", "sequence_number": 0, "response": {"id": "resp_b"}})
+    a, b = observer.snapshot()["responses"]
+    assert a["sequence_forward_gaps"] == a["sequence_forward_missing_total"] == 2
+    assert a["sequence_non_increasing"] == 2
+    assert a["sequence_equal_previous"] == 1
+    assert a["sequence_missing_events"] == 1
+    assert b["sequence_non_increasing"] == b["sequence_forward_gaps"] == 0
+    assert observer.data["unknown_response_events"] == 1
+
+
+def test_oversized_frame_recovery_and_partial_eof_keep_memory_bounded():
+    observer = ResponsesObservation()
+    observer.feed(b"data: " + b"x" * MAX_FRAME_BYTES)
+    observer.feed(b"\r\n\r\n")
+    observer.feed(b"data: invalid\n\n")
+    observer.feed(frame("response.created", 0, response={"id": "resp_valid"}))
+    observer.feed(b'data: {"private":')
+    observer.end(eof=True)
+    stats = observer.snapshot()
+    assert stats["oversized_frames"] == 1
+    assert stats["parse_errors"] == 1
+    assert len(stats["responses"]) == 1
+    assert stats["incomplete_sse_frame"] is True
+    assert "private" not in repr(vars(observer))
+    assert not observer.line and not observer.lines
+    observer.end()  # HTTP close can follow EOF; retain the original coverage gap.
+    assert observer.data["incomplete_sse_frame"] is True
+
+
+def test_raw_tool_and_response_statistics_have_fixed_caps():
+    observer = ResponsesObservation()
+    observer.event({"type": "response.created", "response": {"id": "resp_one"}})
+    for index in range(100):
+        observer.event(
+            {
+                "type": "response.function_call_arguments.delta",
+                "item_id": f"fc_{index}",
+                "output_index": index,
+                "delta": " ",
+            }
+        )
+    for index in range(20):
+        observer.event({"type": "response.created", "response": {"id": f"resp_{index}"}})
+    assert len(observer.tools) == len(observer.fingerprints) == len(observer.aliases) == 64
+    assert len(observer.responses) == 16
+    assert observer.data["statistics_truncated"] is True
+
+
+@pytest.mark.parametrize("size", [1, 37, MAX_FRAME_BYTES * 2])
+def test_oversized_crlf_frame_recovers_across_arbitrary_read_boundaries(size):
+    observer = ResponsesObservation()
+    data = b"data: " + b"x" * MAX_FRAME_BYTES + b"\r\n\r\n"
+    data += frame("response.created", 0, response={"id": "resp_after_large"})
+    for offset in range(0, len(data), size):
+        observer.feed(data[offset : offset + size])
+    assert observer.data["oversized_frames"] == 1
+    assert observer.data["parse_errors"] == 0
+    assert list(observer.responses) == ["resp_after_large"]
+    assert not observer.line and not observer.lines and not observer.dropping
+
+
+def test_alias_statistics_are_bounded_even_when_item_keeps_changing_index():
+    observer = ResponsesObservation()
+    observer.event({"response": {"id": "resp_one"}})
+    for index in range(1000):
+        observer.event(
+            {
+                "type": "response.function_call_arguments.delta",
+                "item_id": "fc_same",
+                "output_index": index,
+                "delta": " ",
+            }
+        )
+    assert len(observer.tools) == 1
+    assert len(observer.aliases) == 128
+    assert observer.data["statistics_truncated"] is True
+
+
+def test_malformed_event_type_cannot_break_passive_observation():
+    observer = ResponsesObservation()
+    observer.feed(frame([], 0, response={"id": "resp_one"}))
+    assert observer.snapshot()["responses"][0]["events"] == 1
+
+
+@pytest.mark.asyncio
+async def test_compressed_body_is_explicitly_skipped_and_sdk_decoding_is_unchanged():
+    body = frame("response.created", 0, response={"id": "resp_one"})
+    compressed = gzip.compress(body)
+
+    class Stream(httpx2.AsyncByteStream):
+        async def __aiter__(self):
+            yield compressed
+
+    attempt = SimpleNamespace(
+        wire_streams=[],
+        data={},
+        headers=lambda _: None,
+        stream_work=lambda *_: None,
+        publish_if_due=lambda: None,
+    )
+    response = httpx2.Response(
+        200,
+        headers={"content-type": "text/event-stream", "content-encoding": "gzip"},
+        stream=Stream(),
+    )
+    token = ACTIVE_ATTEMPT.set(attempt)
+    try:
+        await observe_response_headers(response)
+        assert b"".join([chunk async for chunk in response.aiter_bytes()]) == body
+        stats = attempt.wire_streams[0].observation.snapshot()
+        assert stats["sse_observation"] == "skipped_content_encoding"
+        assert stats["body_bytes"] == len(compressed)
+        assert not stats["responses"] and not stats["parse_errors"]
+    finally:
+        await response.aclose()
+        ACTIVE_ATTEMPT.reset(token)
+
+
+@pytest.mark.parametrize("strict,expected", [(None, "omitted"), (False, "false"), (True, "true")])
+def test_actual_strict_state_and_optional_schema_are_observed_without_mutation(strict, expected):
+    tool = {
+        "type": "function",
+        "name": "click",
+        "parameters": {
+            "type": "object",
+            "properties": {"target": {"anyOf": [{"type": "string"}, {"type": "null"}]}},
+            "required": [],
+        },
+    }
+    if strict is not None:
+        tool["strict"] = strict
+    body = json.dumps(
+        {"tools": [tool], "input": "private prompt", "max_output_tokens": 2048}
+    ).encode()
+    result = request_constraints(body)
+    assert result["max_output_tokens"] == 2048
+    (observed,) = result["tools"]
+    assert observed["strict"] == expected
+    assert observed["schema"]["optional_properties"] == observed["schema"]["open_objects"] == 1
+    assert "strict" not in tool if strict is None else tool["strict"] is strict
+    assert "private" not in json.dumps(result)
+    assert json.loads(body)["tools"][0] == tool
+
+
+def test_constraints_bound_large_requests_namespaces_and_deep_schemas():
+    assert request_constraints(b"x" * (MAX_REQUEST_BYTES + 1)) == {"observation": "body_too_large"}
+    assert request_constraints(b"no JSON") == {"observation": "invalid_json"}
+    tools = [
+        {
+            "type": "namespace",
+            "name": "functions",
+            "tools": [{"type": "function", "name": "click"}],
+        },
+        {"type": "function", "name": "drag", "strict": False},
+    ]
+    result = tool_constraints(tools)
+    assert {t["name"]: t["strict"] for t in result["tools"]} == {
+        "click": "omitted",
+        "drag": "false",
+    }
+    schema = {"type": "object", "properties": {str(i): {"type": "string"} for i in range(2000)}}
+    result = tool_constraints([{"type": "function", "name": "wide", "parameters": schema}])
+    assert result["tools"][0]["schema"]["truncated"] is True
+    assert result["tools"][0]["schema"]["nodes"] <= 1024

tests/unit/test_responses_wire_lifecycle.py

@@ -0,0 +1,323 @@
+import asyncio
+from copy import deepcopy
+import json
+
+import httpx2 as httpx
+from langchain_core.messages import AIMessageChunk
+from langchain_core.callbacks import AsyncCallbackHandler
+from pydantic import SecretStr
+import pytest
+import pytest_asyncio
+
+from artemis.llm.diagnostics import ACTIVE_ATTEMPT
+from artemis.llm.reliability import LLMExhaustedError
+from artemis.llm.router import ModelEndpoint, ModelFactory
+from artemis.mcp.action_specs import tool_declaration
+from artemis.runtime.cancellation import CancellationReason
+from artemis.services import llm
+
+
+def event(kind, sequence, **fields):
+    return (
+        "data: " + json.dumps({"type": kind, "sequence_number": sequence, **fields}) + "\n\n"
+    ).encode()
+
+
+def initial_events():
+    return event(
+        "response.created",
+        0,
+        response={
+            "id": "resp_test",
+            "object": "response",
+            "created_at": 1,
+            "status": "in_progress",
+            "model": "test-model",
+            "output": [],
+        },
+    ) + event(
+        "response.output_item.added",
+        1,
+        output_index=0,
+        item={
+            "type": "function_call",
+            "id": "fc_test",
+            "call_id": "call_test",
+            "name": "action_sequence",
+            "arguments": "",
+            "status": "in_progress",
+        },
+    )
+
+
+class Stream(httpx.AsyncByteStream):
+    def __init__(self):
+        self.fragments = [
+            event(
+                "response.function_call_arguments.delta",
+                2,
+                output_index=0,
+                item_id="fc_test",
+                delta='{"steps":[',
+            )
+        ]
+        self.stalled = asyncio.Event()
+        self.close_calls = 0
+
+    async def __aiter__(self):
+        yield initial_events()
+        for fragment in self.fragments:
+            yield fragment
+        self.stalled.set()
+        await asyncio.Event().wait()
+
+    async def aclose(self):
+        self.close_calls += 1
+
+
+class Engine:
+    current_session_id = "wire-lifecycle"
+    current_step_id = None
+
+    def __init__(self):
+        self.records = []
+        self.retrying = asyncio.Event()
+
+    def record_trace(self, **record):
+        self.records.append(deepcopy(record))
+        if record.get("payload", {}).get("phase") == "retry_wait":
+            self.retrying.set()
+
+    def _publish(self, *_):
+        pass
+
+    @property
+    def data(self):
+        return next(r["payload"] for r in reversed(self.records) if r["type"] == "llm_diagnostic")
+
+
+@pytest_asyncio.fixture
+async def case(monkeypatch, tmp_path):
+    import openai
+    from langchain_openai import ChatOpenAI
+
+    stream, engine, clients, requests = Stream(), Engine(), [], []
+
+    def handle(request):
+        requests.append(json.loads(request.content))
+        return httpx.Response(200, headers={"content-type": "text/event-stream"}, stream=stream)
+
+    def client(**kwargs):
+        value = httpx.AsyncClient(transport=httpx.MockTransport(handle), **kwargs)
+        clients.append(value)
+        return value
+
+    monkeypatch.setattr(openai, "DefaultAsyncHttpxClient", client)
+    monkeypatch.setattr(llm.settings, "OPENAI_API_KEY", SecretStr("test-secret"))
+    monkeypatch.setattr(llm.settings, "OPENAI_BASE_URL", "https://responses.example/v1")
+    monkeypatch.delenv("ARTEMIS_FAKE_LLM", raising=False)
+    monkeypatch.setattr(llm, "_get_current_data_engine", lambda: engine)
+    monkeypatch.setattr(llm, "PAUSE_FILE", tmp_path / "pause")
+    llm._ENDPOINT_BREAKER._states.clear()
+    llm._NON_STREAMING_ENDPOINTS.clear()
+    fallback = llm._FALLBACK_AVAILABLE.set(True)
+
+    def wrapper(timeout=30, max_retries=0):
+        endpoint = ModelEndpoint(
+            model_name="test-model", timeout_seconds=timeout, max_retries=max_retries
+        )
+        model = ModelFactory.create_model(endpoint)
+        assert isinstance(model, ChatOpenAI)
+        return llm.RobustChatModelWrapper(model, endpoint=endpoint).bind_tools(
+            [tool_declaration(n) for n in ("click", "action_sequence", "drag")]
+        )
+
+    yield stream, engine, requests, wrapper
+    llm._FALLBACK_AVAILABLE.reset(fallback)
+    for value in clients:
+        await value.aclose()
+    llm._ENDPOINT_BREAKER._states.clear()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("reason", ["outer_timeout", "request_timeout", "user_stop"])
+async def test_unfinished_arguments_below_length_limit_close_on_all_deadlines(case, reason):
+    stream, engine, requests, wrapper = case
+    if reason == "outer_timeout":
+        running = asyncio.create_task(
+            llm.invoke_llm_with_timeout_message(
+                wrapper().complete([]), timeout_seconds=0.1, hard_timeout=0.1
+            )
+        )
+    elif reason == "request_timeout":
+        running = asyncio.create_task(wrapper(0.1).complete([]))
+    else:
+        running = asyncio.create_task(wrapper().complete([]))
+        await asyncio.wait_for(stream.stalled.wait(), 2)
+        running.cancel(CancellationReason.USER_STOP)
+    with pytest.raises((TimeoutError, LLMExhaustedError, asyncio.CancelledError)):
+        await asyncio.wait_for(running, 3)
+    data = engine.data
+    assert data["tool_argument_chars"] == len('{"steps":[') < 16384
+    assert (
+        data["failure_phase"] == "generating_tool_arguments"
+        if reason == "request_timeout"
+        else data["cancel_phase"] == "generating_tool_arguments"
+    )
+    assert (
+        data["timeout_scope"] == ("outer" if reason == "outer_timeout" else "request")
+        if reason != "user_stop"
+        else data["cancel_reason"] == "user_stop"
+    )
+    assert data["cancel_observed_at"] <= data["ended_at"]
+    (wire,) = data["wire_responses"]
+    assert wire["closed_at"] >= wire["close_started_at"]
+    assert wire["body_eof_observed"] is False
+    assert wire["tools"][0].get("arguments_done_events", 0) == 0
+    assert stream.close_calls == len(requests) == 1
+    assert ACTIVE_ATTEMPT.get() is None
+    assert "test-secret" not in repr(data)
+    assert '{"steps":[' not in repr(data)
+    assert not llm.PAUSE_FILE.exists()
+
+
+@pytest.mark.asyncio
+async def test_overflow_closes_transport_even_while_consumer_is_between_sdk_yields(case):
+    stream, engine, requests, wrapper = case
+    stream.fragments = [
+        event(
+            "response.function_call_arguments.delta",
+            2,
+            output_index=0,
+            item_id="fc_test",
+            delta=" " * 17000,
+        )
+    ]
+    with pytest.raises(LLMExhaustedError):
+        await wrapper().complete([])
+    assert engine.data["stream_guard"]["tool"] == "action_sequence"
+    assert engine.data["wire_responses"][0]["closed_at"]
+    assert stream.close_calls == len(requests) == 1
+    assert not stream.stalled.is_set()
+
+
+@pytest.mark.asyncio
+async def test_overflow_closes_transport_before_waiting_for_retry(case):
+    stream, engine, requests, wrapper = case
+    stream.fragments = [
+        event(
+            "response.function_call_arguments.delta",
+            2,
+            output_index=0,
+            item_id="fc_test",
+            delta=" " * 17000,
+        )
+    ]
+    running = asyncio.create_task(wrapper(max_retries=1).complete([]))
+    await asyncio.wait_for(engine.retrying.wait(), 2)
+    assert stream.close_calls == len(requests) == 1
+    assert engine.data["wire_responses"][0]["closed_at"]
+    running.cancel(CancellationReason.USER_STOP)
+    with pytest.raises(asyncio.CancelledError):
+        await running
+    assert engine.data["cancel_phase"] == "retry_wait"
+
+
+@pytest.mark.asyncio
+async def test_actual_native_schemas_do_not_silently_force_upstream_strict(case):
+    stream, engine, requests, wrapper = case
+    running = asyncio.create_task(wrapper().complete([]))
+    await asyncio.wait_for(stream.stalled.wait(), 2)
+    running.cancel(CancellationReason.USER_STOP)
+    with pytest.raises(asyncio.CancelledError):
+        await running
+    constraints = engine.data["wire_request_constraints"]
+    assert constraints["max_output_tokens"] is None
+    assert {t["name"]: t["strict"] for t in constraints["tools"]} == {
+        "click": "omitted",
+        "action_sequence": "omitted",
+        "drag": "omitted",
+    }
+    assert any(t["schema"]["optional_properties"] for t in constraints["tools"])
+    assert all("strict" not in tool for tool in requests[0]["tools"])
+
+
+@pytest.mark.asyncio
+async def test_live_deltas_are_emitted_before_a_batch_is_flushed(monkeypatch):
+    emitted, resume = asyncio.Event(), asyncio.Event()
+    events = []
+
+    class Model:
+        async def astream(self, *_args, **_kwargs):
+            yield AIMessageChunk(content="first live text")
+            await resume.wait()
+
+    wrapper = llm.RobustChatModelWrapper(Model(), endpoint=ModelEndpoint(model_name="test"))
+    monkeypatch.setattr(wrapper, "_emit_stream_delta", lambda *_: emitted.set())
+    monkeypatch.setattr(llm, "_record_llm_event", lambda *args: events.append(args))
+    running = asyncio.create_task(wrapper._complete_attempt(True, []))
+    await asyncio.wait_for(emitted.wait(), 2)
+    assert not running.done()
+    running.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await running
+    assert any(name == "llm_stream_reset" for name, *_ in events)
+
+
+@pytest.mark.asyncio
+async def test_callback_backpressure_can_leave_wire_ahead_of_sdk_without_prefetch(case):
+    stream, engine, requests, wrapper = case
+    blocked = asyncio.Event()
+    stream.fragments = [
+        b"".join(
+            event(
+                "response.function_call_arguments.delta",
+                n + 2,
+                output_index=0,
+                item_id="fc_test",
+                delta=" ",
+            )
+            for n in range(200)
+        )
+    ]
+
+    class Callback(AsyncCallbackHandler):
+        async def on_llm_new_token(self, token, *, chunk=None, **kwargs):
+            if chunk is not None and any(t.get("args") for t in chunk.message.tool_call_chunks):
+                attempt = ACTIVE_ATTEMPT.get()
+                attempt.publish()
+                blocked.set()
+                await asyncio.Event().wait()
+
+    running = asyncio.create_task(wrapper().complete([], config={"callbacks": [Callback()]}))
+    await asyncio.wait_for(blocked.wait(), 2)
+    wire = engine.data["wire_responses"][0]
+    assert wire["tools"][0]["argument_chars"] == 200
+    assert engine.data["tool_argument_chars"] == 0
+    assert not stream.stalled.is_set()  # no second transport read or background reader
+    running.cancel(CancellationReason.USER_STOP)
+    with pytest.raises(asyncio.CancelledError):
+        await asyncio.wait_for(running, 2)
+    assert stream.close_calls == len(requests) == 1
+    assert engine.data["wire_responses"][0]["closed_at"]
+
+
+@pytest.mark.asyncio
+async def test_unresponsive_close_keeps_user_stop_and_records_cleanup_failure(case, monkeypatch):
+    stream, engine, requests, wrapper = case
+
+    async def stuck_close():
+        stream.close_calls += 1
+        await asyncio.Event().wait()
+
+    monkeypatch.setattr(stream, "aclose", stuck_close)
+    running = asyncio.create_task(wrapper().complete([]))
+    await asyncio.wait_for(stream.stalled.wait(), 2)
+    running.cancel(CancellationReason.USER_STOP)
+    with pytest.raises(asyncio.CancelledError):
+        await asyncio.wait_for(running, 3)
+    assert engine.data["cancel_reason"] == "user_stop"
+    wire = engine.data["wire_responses"][0]
+    assert wire["close_error_type"] == "TimeoutError"
+    assert "closed_at" not in wire
+    assert stream.close_calls == len(requests) == 1