diff --git a/internal/cloud/code-agent-trace-store.ts b/internal/cloud/code-agent-trace-store.ts
index 2f792cf4..2aa23472 100644
--- a/internal/cloud/code-agent-trace-store.ts
+++ b/internal/cloud/code-agent-trace-store.ts
@@ -1,5 +1,5 @@
 /*
- * SPEC: PJ2026-010403 API契约 draft-2026-06-17-r0; PJ2026-0102 Agent编排 draft-2026-06-17-r0; PJ2026-01060505 Workbench Performance draft-2026-06-17-p0
+ * SPEC: PJ2026-010403 API契约 draft-2026-06-17-r0; PJ2026-0102 Agent编排 draft-2026-06-17-r0; PJ2026-01060505 Workbench Performance draft-2026-06-17-p0; PJ2026-0104010803 唯一投影 draft-2026-06-20-p1-zero-split-durable-realtime
  * 职责: Code Agent trace capture。实时内存 trace 可加速 SSE/详情面板，但 append 事件必须同步投影到 durable store。
  */
 import { randomUUID } from "node:crypto";
@@ -249,16 +249,22 @@ export function createDurableCodeAgentTraceStore({ traceStore = defaultCodeAgent
 
 function persistTraceEvent(traceEventStore, event, meta = {}, workbenchEventWriter = null) {
   try {
-    Promise.resolve(traceEventStore.writeAgentTraceEvent({ event }, {
+    const projectionContext = {
       traceId: event.traceId,
       agentSessionId: event.agentSessionId ?? event.sessionId ?? meta.agentSessionId ?? meta.sessionId,
       sessionId: event.sessionId ?? meta.sessionId
-    })).catch(() => {});
+    };
+    Promise.resolve(traceEventStore.writeAgentTraceEvent({ event }, projectionContext)).catch((error) => {
+      console.error(`[workbench-projection] durable trace event write failed: traceId=${event.traceId} sourceEventId=${event.sourceEventId ?? "none"} error=${error?.message ?? error}`);
+    });
     if (typeof workbenchEventWriter === "function") {
-      Promise.resolve(workbenchEventWriter(event, meta)).catch(() => {});
+      Promise.resolve(workbenchEventWriter(event, meta)).catch((error) => {
+        console.error(`[workbench-projection] workbench event writer failed: traceId=${event.traceId} error=${error?.message ?? error}`);
+      });
     }
-  } catch {
-    // Trace capture must not fail the user turn when the durable projection is temporarily unavailable.
+  } catch (error) {
+    // Trace capture must not fail the user turn, but projection write errors must be visible for diagnostics.
+    console.error(`[workbench-projection] persistTraceEvent sync error: traceId=${event.traceId} error=${error?.message ?? error}`);
   }
 }
 
diff --git a/internal/cloud/workbench-projection-writer.ts b/internal/cloud/workbench-projection-writer.ts
index 13a2d959..32e368bc 100644
--- a/internal/cloud/workbench-projection-writer.ts
+++ b/internal/cloud/workbench-projection-writer.ts
@@ -1,5 +1,5 @@
 /*
- * SPEC: PJ2026-0104010803 Workbench唯一投影 draft-2026-06-18-p0-unique-projection; PJ2026-010205 HWLAB接入 draft-2026-06-17-r0.
+ * SPEC: PJ2026-0104010803 Workbench唯一投影 draft-2026-06-18-p0-unique-projection; draft-2026-06-20-p1-zero-split-durable-realtime; PJ2026-010205 HWLAB接入 draft-2026-06-17-r0.
  * 职责: WorkbenchProjectionWriter 组件入口。唯一封装 Code Agent/AgentRun facts 到 Workbench session projection facts 的持久化写入。
  */
 import { createHash } from "node:crypto";
diff --git a/internal/db/migrations/0001_cloud_core_skeleton.sql b/internal/db/migrations/0001_cloud_core_skeleton.sql
index 76c86391..6b4efac5 100644
--- a/internal/db/migrations/0001_cloud_core_skeleton.sql
+++ b/internal/db/migrations/0001_cloud_core_skeleton.sql
@@ -294,6 +294,8 @@ CREATE TABLE IF NOT EXISTS workbench_trace_events (
 );
 CREATE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_seq ON workbench_trace_events(trace_id, source_seq, projected_seq, id);
 CREATE INDEX IF NOT EXISTS idx_workbench_trace_events_session_seq ON workbench_trace_events(session_id, source_seq, projected_seq, id);
+CREATE UNIQUE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_source_event ON workbench_trace_events(trace_id, source_event_id) WHERE source_event_id IS NOT NULL;
+CREATE UNIQUE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_projected_seq ON workbench_trace_events(trace_id, projected_seq);
 
 CREATE TABLE IF NOT EXISTS workbench_projection_checkpoints (
   trace_id TEXT PRIMARY KEY,
@@ -316,6 +318,25 @@ CREATE TABLE IF NOT EXISTS workbench_projection_checkpoints (
 CREATE INDEX IF NOT EXISTS idx_workbench_projection_checkpoints_status_updated ON workbench_projection_checkpoints(projection_status, updated_at DESC, trace_id);
 CREATE INDEX IF NOT EXISTS idx_workbench_projection_checkpoints_session_updated ON workbench_projection_checkpoints(session_id, updated_at DESC, trace_id);
 
+CREATE TABLE IF NOT EXISTS workbench_projection_outbox (
+  outbox_seq BIGSERIAL PRIMARY KEY,
+  trace_id TEXT NOT NULL,
+  session_id TEXT,
+  turn_id TEXT,
+  message_id TEXT,
+  projected_seq INTEGER NOT NULL DEFAULT 0,
+  source_seq INTEGER NOT NULL DEFAULT 0,
+  source_event_id TEXT,
+  commit_type TEXT NOT NULL DEFAULT 'event',
+  terminal BOOLEAN NOT NULL DEFAULT false,
+  sealed BOOLEAN NOT NULL DEFAULT false,
+  payload_json TEXT NOT NULL DEFAULT '{}',
+  created_at TEXT NOT NULL
+);
+CREATE INDEX IF NOT EXISTS idx_workbench_projection_outbox_trace_seq ON workbench_projection_outbox(trace_id, outbox_seq);
+CREATE INDEX IF NOT EXISTS idx_workbench_projection_outbox_session_seq ON workbench_projection_outbox(session_id, outbox_seq);
+CREATE INDEX IF NOT EXISTS idx_workbench_projection_outbox_after_seq ON workbench_projection_outbox(outbox_seq);
+
 INSERT INTO workbench_sessions (
   session_id,
   owner_user_id,
diff --git a/internal/db/runtime-store.ts b/internal/db/runtime-store.ts
index b3e56921..3d32b60a 100644
--- a/internal/db/runtime-store.ts
+++ b/internal/db/runtime-store.ts
@@ -1,5 +1,5 @@
 /*
- * SPEC: PJ2026-010403 API契约 draft-2026-06-17-r0; PJ2026-0102 Agent编排 draft-2026-06-17-r0; PJ2026-0104010803 Workbench唯一投影 draft-2026-06-19-p1-agentrun-incremental-cursor.
+ * SPEC: PJ2026-010403 API契约 draft-2026-06-17-r0; PJ2026-0102 Agent编排 draft-2026-06-17-r0; PJ2026-0104010803 Workbench唯一投影 draft-2026-06-19-p1-agentrun-incremental-cursor; draft-2026-06-20-p1-zero-split-durable-realtime.
  * 职责: Cloud runtime durable store。Code Agent trace/session/projection cursor 投影事实必须从同一持久化适配器写入和恢复。
  */
 import { createHash, randomUUID } from "node:crypto";
@@ -1276,6 +1276,48 @@ export class PostgresCloudRuntimeStore {
     for (const fact of result.facts.turns) await this.persistWorkbenchTurnFact(fact);
     for (const fact of result.facts.traceEvents) await this.persistWorkbenchTraceEventFact(fact);
     for (const fact of result.facts.checkpoints) await this.persistWorkbenchProjectionCheckpoint(fact);
+    for (const fact of result.facts.traceEvents) {
+      try {
+        await this.persistWorkbenchProjectionOutbox({
+        traceId: fact.traceId,
+        sessionId: fact.sessionId,
+        turnId: fact.turnId,
+        messageId: fact.messageId,
+        projectedSeq: fact.projectedSeq,
+        sourceSeq: fact.sourceSeq,
+        sourceEventId: fact.sourceEventId,
+        commitType: fact.terminal ? "terminal" : "event",
+        terminal: Boolean(fact.terminal),
+        sealed: Boolean(fact.sealed),
+        payload: { type: fact.eventType, projectedSeq: fact.projectedSeq, valuesRedacted: true },
+        createdAt: fact.occurredAt ?? fact.updatedAt ?? this.now()
+      });
+    } catch (outboxError) {
+      console.error(`[workbench-projection] outbox write failed: traceId=${fact.traceId} projectedSeq=${fact.projectedSeq} error=${outboxError?.message ?? outboxError}`);
+    }
+  }
+    for (const fact of result.facts.turns) {
+      if (fact.terminal || fact.sealed) {
+        try {
+          await this.persistWorkbenchProjectionOutbox({
+          traceId: fact.traceId,
+          sessionId: fact.sessionId,
+          turnId: fact.turnId,
+          messageId: fact.messageId,
+          projectedSeq: fact.projectedSeq,
+          sourceSeq: fact.sourceSeq,
+          sourceEventId: fact.sourceEventId,
+          commitType: "terminal",
+          terminal: true,
+          sealed: true,
+          payload: { status: fact.status, failureKind: fact.failureKind, valuesRedacted: true },
+          createdAt: fact.updatedAt ?? this.now()
+        });
+      } catch (outboxError) {
+        console.error(`[workbench-projection] terminal outbox write failed: traceId=${fact.traceId} error=${outboxError?.message ?? outboxError}`);
+      }
+    }
+  }
     return withPersistence(result, this.summary());
   }
 
@@ -1632,6 +1674,51 @@ export class PostgresCloudRuntimeStore {
     );
   }
 
+  async persistWorkbenchProjectionOutbox(record) {
+    await this.query(
+      "INSERT INTO workbench_projection_outbox (trace_id, session_id, turn_id, message_id, projected_seq, source_seq, source_event_id, commit_type, terminal, sealed, payload_json, created_at) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12)",
+      [record.traceId, record.sessionId, record.turnId, record.messageId, record.projectedSeq, record.sourceSeq, record.sourceEventId, record.commitType ?? "event", Boolean(record.terminal), Boolean(record.sealed), stableJson(record.payload ?? record), record.createdAt ?? this.now()]
+    );
+  }
+
+  async readWorkbenchProjectionOutbox({ afterSeq = 0, limit = 100, traceId = null, sessionId = null } = {}) {
+    const params = [];
+    let where = "outbox_seq > $1";
+    params.push(Number(afterSeq) || 0);
+    let paramIdx = 2;
+    if (traceId) {
+      where += ` AND trace_id = $${paramIdx}`;
+      params.push(traceId);
+      paramIdx += 1;
+    }
+    if (sessionId) {
+      where += ` AND session_id = $${paramIdx}`;
+      params.push(sessionId);
+      paramIdx += 1;
+    }
+    params.push(Math.min(Math.max(Number(limit) || 100, 1), 500));
+    const result = await this.query(
+      `SELECT outbox_seq, trace_id, session_id, turn_id, message_id, projected_seq, source_seq, source_event_id, commit_type, terminal, sealed, payload_json, created_at FROM workbench_projection_outbox WHERE ${where} ORDER BY outbox_seq ASC LIMIT $${paramIdx}`,
+      params
+    );
+    return (result.rows ?? []).map((row) => ({
+      outboxSeq: Number(row.outbox_seq),
+      traceId: row.trace_id,
+      sessionId: row.session_id,
+      turnId: row.turn_id,
+      messageId: row.message_id,
+      projectedSeq: Number(row.projected_seq),
+      sourceSeq: Number(row.source_seq),
+      sourceEventId: row.source_event_id,
+      commitType: row.commit_type,
+      terminal: Boolean(row.terminal),
+      sealed: Boolean(row.sealed),
+      payload: typeof row.payload_json === "string" ? JSON.parse(row.payload_json) : row.payload_json,
+      createdAt: row.created_at,
+      valuesPrinted: false
+    }));
+  }
+
   async persistWorkbenchProjectionCheckpoint(record) {
     await this.query(
       "INSERT INTO workbench_projection_checkpoints (trace_id, session_id, turn_id, run_id, command_id, projected_seq, source_seq, source_event_id, projection_status, projection_health, terminal, sealed, diagnostic_json, checkpoint_json, created_at, updated_at) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16) ON CONFLICT (trace_id) DO UPDATE SET session_id = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.session_id ELSE workbench_projection_checkpoints.session_id END, turn_id = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.turn_id ELSE workbench_projection_checkpoints.turn_id END, run_id = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.run_id ELSE workbench_projection_checkpoints.run_id END, command_id = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.command_id ELSE workbench_projection_checkpoints.command_id END, projected_seq = GREATEST(workbench_projection_checkpoints.projected_seq, EXCLUDED.projected_seq), source_seq = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.source_seq ELSE workbench_projection_checkpoints.source_seq END, source_event_id = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.source_event_id ELSE workbench_projection_checkpoints.source_event_id END, projection_status = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.projection_status ELSE workbench_projection_checkpoints.projection_status END, projection_health = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.projection_health ELSE workbench_projection_checkpoints.projection_health END, terminal = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.terminal ELSE workbench_projection_checkpoints.terminal END, sealed = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.sealed ELSE workbench_projection_checkpoints.sealed END, diagnostic_json = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.diagnostic_json ELSE workbench_projection_checkpoints.diagnostic_json END, checkpoint_json = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.checkpoint_json ELSE workbench_projection_checkpoints.checkpoint_json END, updated_at = CASE WHEN EXCLUDED.projected_seq >= workbench_projection_checkpoints.projected_seq THEN EXCLUDED.updated_at ELSE workbench_projection_checkpoints.updated_at END",
diff --git a/internal/db/schema.ts b/internal/db/schema.ts
index 794d2d43..ac93ad39 100644
--- a/internal/db/schema.ts
+++ b/internal/db/schema.ts
@@ -5,7 +5,7 @@
 import { TABLES } from "../protocol/index.mjs";
 
 export const CLOUD_CORE_MIGRATION_ID = "0001_cloud_core_skeleton";
-export const CLOUD_RUNTIME_DURABLE_ADAPTER_SCHEMA_VERSION = "runtime-durable-postgres-v4";
+export const CLOUD_RUNTIME_DURABLE_ADAPTER_SCHEMA_VERSION = "runtime-durable-postgres-v5";
 export const CLOUD_RUNTIME_DURABLE_MIGRATION_TABLE = "hwlab_schema_migrations";
 
 export const FROZEN_CLOUD_CORE_TABLES = Object.freeze([...TABLES]);
@@ -266,6 +266,21 @@ export const CLOUD_RUNTIME_DURABLE_TABLE_COLUMNS = Object.freeze({
     "checkpoint_json",
     "created_at",
     "updated_at"
+  ]),
+  workbench_projection_outbox: Object.freeze([
+    "outbox_seq",
+    "trace_id",
+    "session_id",
+    "turn_id",
+    "message_id",
+    "projected_seq",
+    "source_seq",
+    "source_event_id",
+    "commit_type",
+    "terminal",
+    "sealed",
+    "payload_json",
+    "created_at"
   ])
 });