docs: plan the implementation for issue #11

Eight tasks against the approved design, ordered so the port and both
telemetry backends land before the three call paths that feed them.

Writing the plan turned up a third telemetry path the design missed:
OcrClient emits through the same helper and builds its ChatRequest on
the spot, just as embedding does. OCR rows share the table with chat
rows, so leaving them out would put a hole in a multi-tenant caller's
audit trail, and the same irreversibility argument applies. Listed as
Task 6 and flagged as beyond the approved scope -- it may be dropped,
but only by stating the limitation in the CHANGELOG, not silently.

The integration task pins the issue's own argument as a test: build a
22-column table, open it with the current recorder, and assert the old
rows read back as the empty string rather than NULL -- NULL under an
RLS policy is invisible to everyone, not merely unassigned.

research-wiki/designs/issue11-caller-dimensions.md

@@ -7,7 +7,9 @@ date: 2026-08-17
 
 # 调用方自定义维度设计(issue #11)
 
-正文: `2026-08-17-issue11-caller-dimensions-design.md`。状态: 待 Codex 审 → 待人类审批。
+正文: `2026-08-17-issue11-caller-dimensions-design.md`。状态: **已人类审批(2026-08-17)**,进入 writing-plans。
+
+审批时三个待定项按设计原值定稿,人类未提出改动: `meta` key 数量上限 16 / `str` value 上限 256 / `tenant_id` 上限 128(量级推断,无本项目实测依据);库不自动建索引、不自动启用 RLS(GovDoc 需 DBA 执行模板 SQL 才拿到数据库层隔离);`_BACKFILL` 自动 ALTER 降级议题**不纳入本次**。
 
 - **选定方案**: `tenant_id` 提真实列(RLS 硬需求)+ `meta` JSON 容器承载任意调用方自定义 KV(**默认不建索引**)。`chat()`/`embed()` 各增两个带默认值的 keyword-only 参数,签名冻结承诺不破。端口 22 → 24 字段。
 - **范围收窄(2026-08-17 人类决策)**: 只做**调用方自定义**的维度;请求自带信息(模型名/供应商/源名)继续走现有列,库不往 `meta` 写任何自采信息。issue 第 4 条(保留期与访问控制)另开。