Sync latest main into v3 performance integration

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mega2"
-version = "0.42.20"
+version = "0.42.23"
 edition = "2024"
 license = "MIT OR Apache-2.0"
 description = "Monorepo engine and Git hosting server for AI agents: trunk-based storage, Git Smart HTTP, Git LFS, OCI registry, and Agent Session Capture"

docs/architecture.md

@@ -115,6 +115,8 @@ See the [Configuration Guide](./configuration.md) for SecretRef settings and val
 | SSH | `service ssh` (dedicated port) | read-only (upload-pack) in storage-only; `git.ssh_receive_pack=false` is mandatory — omitting it refuses startup |
 | Git LFS | `/info/lfs` + `/api/v1/lfs` | mounted in both modes; write authorization follows `push_auth` |
 | Product API | `/api/v1/*` (status, file/blob, file/tree, preview reads + create-entry/delete-entry/move-entry/edit/save writes + tags) | trunk / storage-only mode |
+| Git view URLs (read-only) | `/.filter/<filter_id>.git`, `/.view/<name>.git`, `/.view/<name>@<version>.git` (HTTP and SSH upload-pack) | `[views].enabled` defaults off and requires restart; receive-pack is rejected and LFS under view prefixes returns 404 |
+| Views API | `/api/v1/views` (`POST ?wait=true` registration and `GET ?name=&version=`), `GET /api/v1/views/{filter_id}`, `GET /api/v1/views/metrics`; see [views operations](./deploy-trunk.md) | `[views].enabled` defaults off and requires restart; mounted only in trunk / storage-only, returns 404 when disabled |
 | OCI registry | `/v2/` | `[oci].enabled` and storage-only; fail-closed (not registered) under review |
 | Agent Capture | `/api/v1/agent-capture` | `[agent_capture].enabled` and storage-only |
 | MST/2 snapshot surface | `/api/v2` | nest is static; handlers fail closed unless `[mst2].enabled`; toggling needs a restart |

docs/architecture.zh.md

@@ -114,6 +114,8 @@ HTTP router 在 `server::http_server::app`（`src/server/http_server.rs:681`）
 | SSH | `service ssh`（独立端口） | storage-only 下只读（upload-pack）；`git.ssh_receive_pack=false` 为强制项，省略会拒绝启动 |
 | Git LFS | `/info/lfs` + `/api/v1/lfs` | 两种形态均挂载；写授权随 `push_auth` |
 | 产品 API | `/api/v1/*`（status、file/blob、file/tree、preview 读 + create-entry/delete-entry/move-entry/edit/save 写 + tags） | trunk / storage-only 形态 |
+| Git 视图 URL（只读） | `/.filter/<filter_id>.git`、`/.view/<name>.git`、`/.view/<name>@<version>.git`（HTTP 与 SSH upload-pack） | `[views].enabled` 缺省关闭，重启生效；receive-pack 拒绝，视图前缀 LFS 返回 404 |
+| 视图 API | `/api/v1/views`（`POST ?wait=true` 注册、`GET ?name=&version=`）、`GET /api/v1/views/{filter_id}`、`GET /api/v1/views/metrics`；请求见[视图运维](./deploy-trunk.md) | `[views].enabled` 缺省关闭，重启生效；只在 trunk / storage-only 挂载，关闭时返回 404 |
 | OCI registry | `/v2/` | `[oci].enabled` 且 storage-only；review 形态 fail-closed 不注册 |
 | Agent Capture | `/api/v1/agent-capture` | `[agent_capture].enabled` 且 storage-only |
 | MST/2 快照面 | `/api/v2` | nest 静态注册，handler 在 `[mst2].enabled` 为 false 时 fail-closed；切换需重启 |

docs/deploy-trunk.md

@@ -487,7 +487,7 @@ DELETE FROM mega_view_root_chain_scan;
 
 `recycle-filter` 与 `rebuild-all` 都有显式事务。`COMMIT` 之前的语句失败时，psql 会停止并断开连接，事务不会提交。recycle-filter 只回收目标过滤器的派生提交映射与对象引用，保留对象以供后续清扫；rebuild-all 清掉全部派生状态。两者把过滤器置为回收态：`projected_seq = 0`，且 `ready_seq`、`warming_since` 为 NULL。worker 只为活跃视图（`ready_seq` 或 `warming_since` 非空）执行 catch_up，因此回收态视图会等待重新预热。clear-root-chain-scan 只清暂存表，不改视图状态；下一次根链扩展会按当前的 `main@/` 重新判定。
 
-三段 SQL 都不用 `TRUNCATE`，不删除 `mega_view_filter`、`mega_view` 或 `mega_view_register_log`，也不改 `last_access_at` 与过滤器定义列。rebuild-all 是全表 `DELETE`，停服窗口随派生行数增长。本节只记录停服运维与恢复语义；视图 Git URL 的对象读取尚未开放。
+三段 SQL 都不用 `TRUNCATE`，不删除 `mega_view_filter`、`mega_view` 或 `mega_view_register_log`，也不改 `last_access_at` 与过滤器定义列。rebuild-all 是全表 `DELETE`，停服窗口随派生行数增长。本节记录停服运维与恢复语义；视图 Git URL 已支持只读 clone 与 fetch，用法见[用户指南](./user-guide.zh.md#27-视图-url只读)。
 
 投影停止时，首个失败点会以 ERROR 事件给出。除 message 外，停止告警字段为 `metric=view_projection_stops_total`、`filter_id`、`s`、`commit_id`、`reason`；当 reason 是 `row_absent` 或 `unparsable` 时还带 `tree_id`。例如：`metric=view_projection_stops_total s=7 reason=row_absent`。按 reason 处理：