fix: drop the conflict target so partitioned tables can accept writes

PG requires a partitioned table's unique constraints to include the
partition key, so issue #12's RANGE partitioning on created_at forces
the primary key to (call_id, created_at). The old
`ON CONFLICT (call_id) DO NOTHING` then matches no constraint and PG
rejects every row with

    there is no unique or exclusion constraint matching the
    ON CONFLICT specification

which the recorder swallows as a per-row warning: telemetry would go
silently dark under a partitioned deployment. The target-free form is
valid on both table shapes and is literally equivalent on a plain table
(the primary key is its only unique constraint). SQLite's
`INSERT OR IGNORE` already carries no target and is untouched.

Integration coverage on the real PG instance, both inside self-created
temp schemas: a plain table still keeps one row per call_id, and a
table partitioned by created_at now accepts writes and reads them back.
The second case was red before this change with the error above.

src/polygateway/telemetry/schema.py

@@ -155,6 +155,13 @@ def insert_sql(backend: str, columns: Sequence[str]) -> str:
     字符串拼进 SQL(占位符只保护值,保护不了列名)。sqlite 用 `?`、postgres 用 `$n`,
     两端的重复键处理都不绑定具体约束名(`INSERT OR IGNORE` / `ON CONFLICT`)。
 
+    **PG 的 `ON CONFLICT` 一律不带冲突目标,不得"顺手"补回 `(call_id)`**: PG 要求
+    分区表的唯一约束必须包含分区键,按 `created_at` 分区(issue #12 的保留期方案)后
+    主键变成 `(call_id, created_at)`,带目标的语句匹配不到任何约束,PG 直接拒收
+    ("there is no unique or exclusion constraint matching the ON CONFLICT
+    specification"),而遥测写失败只逐行 warning——分区部署下会全线静默丢数据。
+    无目标版本在两种表形态上都合法,普通表上语义逐字等价(表上只有主键一个唯一约束)。
+
     Args:
         backend: `"sqlite"` 或 `"postgres"`。
         columns: 要写入的列,顺序即占位符顺序(调用方须按同序取值)。
@@ -176,7 +183,7 @@ def insert_sql(backend: str, columns: Sequence[str]) -> str:
         placeholders = ", ".join("?" for _ in selected)
         return f"INSERT OR IGNORE INTO {TABLE} ({names}) VALUES ({placeholders})"
     placeholders = ", ".join(f"${i + 1}" for i in range(len(selected)))
-    return f"INSERT INTO {TABLE} ({names}) VALUES ({placeholders}) ON CONFLICT (call_id) DO NOTHING"
+    return f"INSERT INTO {TABLE} ({names}) VALUES ({placeholders}) ON CONFLICT DO NOTHING"
 
 
 def telemetry_schema_sql(backend: str) -> str:

tests/integration/test_postgres_telemetry.py

@@ -14,6 +14,7 @@ import asyncio
 import json
 import os
 import re
+from datetime import UTC, datetime, timedelta
 from uuid import uuid4
 
 import pytest
@@ -628,3 +629,123 @@ class TestCallerDimensionsAcceptance:
             assert any("写入失败" in m for m in captured_warnings)
         finally:
             await recorder.aclose()
+
+
+# issue #12 的目标表形态: 按 created_at 做 RANGE 分区(过期清理 DROP PARTITION 而非 DELETE)。
+# PG 强制分区表的唯一约束必须包含分区键,故主键只能是 (call_id, created_at) ——
+# 这正是带目标的 `ON CONFLICT (call_id)` 再也匹配不到约束的现场。
+_PARTITIONED_DDL = """
+CREATE TABLE {schema}.llm_calls (
+    call_id            TEXT NOT NULL,
+    parent_call_id     TEXT,
+    session_id         TEXT,
+    model              TEXT NOT NULL,
+    provider           TEXT NOT NULL,
+    source_name        TEXT NOT NULL,
+    messages           TEXT NOT NULL,
+    response           TEXT NOT NULL,
+    thinking           TEXT NOT NULL DEFAULT '',
+    prompt_tokens      INTEGER NOT NULL,
+    completion_tokens  INTEGER NOT NULL,
+    usage_source       TEXT NOT NULL,
+    latency_ms         INTEGER NOT NULL,
+    ttft_ms            DOUBLE PRECISION,
+    max_inter_token_ms DOUBLE PRECISION,
+    cache_hit          BOOLEAN NOT NULL DEFAULT FALSE,
+    error              TEXT,
+    cost               DOUBLE PRECISION,
+    created_at         TIMESTAMPTZ NOT NULL DEFAULT now(),
+    cached_prompt_tokens INTEGER,
+    model_reported       TEXT,
+    sampling             TEXT,
+    reasoning_tokens     INTEGER,
+    tenant_id            TEXT NOT NULL DEFAULT '',
+    meta                 JSONB NOT NULL DEFAULT '{{}}'::jsonb,
+    PRIMARY KEY (call_id, created_at)
+) PARTITION BY RANGE (created_at)
+"""
+
+_PARTITION_DDL = (
+    "CREATE TABLE {schema}.llm_calls_current PARTITION OF {schema}.llm_calls "
+    "FOR VALUES FROM ('{start}') TO ('{end}')"
+)
+
+
+def _current_month_bounds() -> tuple[str, str]:
+    """当前月的 [月初, 下月初) 边界字面量;分区键落在区间外会因找不到分区而写失败。"""
+    now = datetime.now(UTC)
+    start = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
+    end = (start + timedelta(days=32)).replace(day=1)
+    fmt = "%Y-%m-%d %H:%M:%S%z"
+    return start.strftime(fmt), end.strftime(fmt)
+
+
+@pytest.fixture
+async def partitioned_schema(dsn):
+    """自建临时 schema 里造一张按 created_at RANGE 分区的表 + 覆盖当前月的分区。
+
+    与 legacy_schema 同款隔离: 绝不碰共享的 public.llm_calls,teardown 只 DROP
+    自己建的 schema(CASCADE 连分区一并删)。
+    """
+    import asyncpg
+
+    name = f"pgwtest_part_{uuid4().hex[:8]}"
+    start, end = _current_month_bounds()
+    conn = await asyncpg.connect(dsn, timeout=10)
+    try:
+        await conn.execute(f"CREATE SCHEMA {name}")
+        await conn.execute(_PARTITIONED_DDL.format(schema=name))
+        await conn.execute(_PARTITION_DDL.format(schema=name, start=start, end=end))
+    finally:
+        await conn.close()
+    yield _search_path_dsn(dsn, name), name
+    conn = await asyncpg.connect(dsn, timeout=10)
+    try:
+        await conn.execute(f"DROP SCHEMA {name} CASCADE")
+    finally:
+        await conn.close()
+
+
+class TestConflictTargetFreeInsert:
+    """issue #13: INSERT 不绑定冲突目标,普通表与分区表两种形态都写得进去。"""
+
+    async def test_plain_table_still_dedupes_by_call_id(self, fresh_schema, captured_warnings):
+        """普通表上语义不变: 重复 call_id 仍只落一行,且不是被拒后丢弃。
+
+        表上只有主键这一个唯一约束,故无目标的 DO NOTHING 与 `(call_id)` 逐字等价;
+        断言"无写入失败 warning"是为了区分"冲突被忽略"与"整条被 PG 拒收"。
+        """
+        fresh_dsn, _ = fresh_schema
+        recorder = PostgresRecorder(fresh_dsn)
+        try:
+            await _record_minimal(recorder, call_id=_cid("nodup"))
+            await _record_minimal(recorder, call_id=_cid("nodup"), response="second")
+            assert [m for m in captured_warnings if "写入失败" in m] == []
+            rows = await _fetch(
+                fresh_dsn, "SELECT response FROM llm_calls WHERE call_id = $1", _cid("nodup")
+            )
+            assert [r["response"] for r in rows] == ["ok"]  # 首行胜出,写入幂等
+        finally:
+            await recorder.aclose()
+
+    async def test_partitioned_table_accepts_writes(self, partitioned_schema, captured_warnings):
+        """分区表上写入成功且能读回——改动前这里必红。
+
+        带目标的 `ON CONFLICT (call_id)` 在主键为 `(call_id, created_at)` 的表上
+        匹配不到任何约束,PG 报 "there is no unique or exclusion constraint matching
+        the ON CONFLICT specification";该错误被逐行降级吞成 warning,于是分区部署下
+        遥测全线写不进去却一声不吭,只能靠"读不回来"暴露。
+        """
+        part_dsn, _ = partitioned_schema
+        recorder = PostgresRecorder(part_dsn)
+        try:
+            await _record_minimal(recorder, call_id=_cid("part"), tenant_id="tenant-p")
+            assert [m for m in captured_warnings if "写入失败" in m] == []
+            rows = await _fetch(
+                part_dsn,
+                "SELECT call_id, tenant_id FROM llm_calls WHERE call_id = $1",
+                _cid("part"),
+            )
+            assert [(r["call_id"], r["tenant_id"]) for r in rows] == [(_cid("part"), "tenant-p")]
+        finally:
+            await recorder.aclose()

tests/unit/test_telemetry.py

@@ -131,7 +131,9 @@ _FROZEN_PG_INSERT = (
     "sampling, reasoning_tokens, tenant_id, meta) "
     "VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, "
     "$19, $20, $21, $22, $23, $24) "
-    "ON CONFLICT (call_id) DO NOTHING"
+    # 无冲突目标(issue #13 Task 2): 带 `(call_id)` 的版本在按 created_at 分区、
+    # 主键为 (call_id, created_at) 的表上匹配不到约束,PG 直接拒收整条写入
+    "ON CONFLICT DO NOTHING"
 )
 
 
@@ -174,16 +176,17 @@ class TestSchemaModule:
         assert all("IF NOT EXISTS" not in stmt for _, stmt in PG_BACKFILL)
 
     def test_insert_sql_reproduces_the_frozen_statements(self):
-        """`insert_sql(backend, COLUMNS)` 必须与搬迁前的 `_INSERT` 逐字节相同。"""
+        """`insert_sql(backend, COLUMNS)` 与搬迁前的 `_INSERT` 一致(PG 侧去掉冲突目标)。"""
         from polygateway.telemetry.schema import COLUMNS, insert_sql
 
         assert insert_sql("sqlite", COLUMNS) == _FROZEN_SQLITE_INSERT
         assert insert_sql("postgres", COLUMNS) == _FROZEN_PG_INSERT
         # 裁剪列表按位置占位符重新编号,不留空洞
         assert insert_sql("postgres", ["call_id", "model"]) == (
-            "INSERT INTO llm_calls (call_id, model) VALUES ($1, $2) "
+            "INSERT INTO llm_calls (call_id, model) VALUES ($1, $2) ON CONFLICT DO NOTHING"
-            "ON CONFLICT (call_id) DO NOTHING"
         )
+        # 冲突目标不得被"顺手"补回: 分区表上它会让每一条遥测都被 PG 拒收
+        assert "ON CONFLICT (" not in insert_sql("postgres", COLUMNS)
 
     def test_insert_sql_rejects_foreign_columns_and_backends(self):
         """列名来自数据库探测结果而非常量,子集校验是唯一的注入面闸门。"""