docs: plan both telemetry changes down to the task level

Twelve tasks across the two plans, each with the files it touches, the
evidence it has to produce, and the command that proves it. #13 goes
first: both branches edit config.py and client.py, and #12's
partitioning template leans on the schema SQL helper and the untargeted
conflict clause that #13 introduces.

Writing the cap plan surfaced a trap worth its own guard. digest_messages
appends the very same dict when a message's content is not a list, so
the telemetry copy, the caller's messages and the cache key all share
one object -- capping in place would poison the caller's request and the
cache key at once, silently. Two red-line tests now pin that down, and
the plan asks for an in-place version to be written and run first, to
prove the tests actually catch it.

research-wiki/index.md

@@ -1,6 +1,6 @@
 # Research Wiki 索引
 
-> 自动生成，更新时间：2026-08-19 12:45 UTC
+> 自动生成，更新时间：2026-08-19 13:10 UTC
 
 ## design (34)
 - [2026-07-20-m1-core-design](designs/2026-07-20-m1-core-design.md) `design:2026-07-20-m1-core-design`
@@ -52,7 +52,7 @@
 - [P7 OCR soak 验收: 99.73% 与 13 不变量全 PASS](findings/p7-ocr-soak.md) `finding:p7-ocr-soak`
 - [推理开关与 reasoning_tokens: 供应商实测与业界做法](findings/2026-08-02-thinking-switch-and-reasoning-tokens.md) `finding:2026-08-02-thinking-switch-and-reasoning-tokens`
 
-## plan (25)
+## plan (29)
 - [2026-07-20-m1-core-plan](plans/2026-07-20-m1-core-plan.md) `plan:2026-07-20-m1-core-plan`
 - [2026-07-20-m2-distributed-plan](plans/2026-07-20-m2-distributed-plan.md) `plan:2026-07-20-m2-distributed-plan`
 - [2026-07-21-m25-resilience-plan](plans/2026-07-21-m25-resilience-plan.md) `plan:2026-07-21-m25-resilience-plan`
@@ -65,6 +65,8 @@
 - [2026-08-06-issue8-stall-budget](plans/2026-08-06-issue8-stall-budget.md) `plan:2026-08-06-issue8-stall-budget`
 - [2026-08-16-issue10-error-body-retention](plans/2026-08-16-issue10-error-body-retention.md) `plan:2026-08-16-issue10-error-body-retention`
 - [2026-08-17-issue11-caller-dimensions](plans/2026-08-17-issue11-caller-dimensions.md) `plan:2026-08-17-issue11-caller-dimensions`
+- [2026-08-19-issue12-telemetry-retention](plans/2026-08-19-issue12-telemetry-retention.md) `plan:2026-08-19-issue12-telemetry-retention`
+- [2026-08-19-issue13-schema-mode](plans/2026-08-19-issue13-schema-mode.md) `plan:2026-08-19-issue13-schema-mode`
 - [est_tokens 解耦实施计划](plans/est-tokens-decoupling.md) `plan:est-tokens-decoupling`
 - [issue #8 实施计划: stall 非生产性等待口径](plans/issue8-stall-budget-plan.md) `plan:issue8-stall-budget-plan`
 - [M1 核心里程碑实现计划](plans/m1-core-plan.md) `plan:m1-core-plan`
@@ -74,6 +76,8 @@
 - [M4 迁移实现计划(T0-T14)](plans/m4-migration.md) `plan:m4-migration`
 - [响应可观测字段扩展实现计划](plans/response-observability-fields.md) `plan:response-observability-fields`
 - [实现计划: HTTP 错误响应体留存(Issue #10)](plans/issue10-error-body-retention-plan.md) `plan:issue10-error-body-retention-plan`
+- [实现计划: issue12-telemetry-retention](plans/plan-issue12-telemetry-retention.md) `plan:plan-issue12-telemetry-retention`
+- [实现计划: issue13-schema-mode](plans/plan-issue13-schema-mode.md) `plan:plan-issue13-schema-mode`
 - [实现计划: 治理后端故障归位为 scope 级不可用(Issue #7)](plans/governance-backend-error.md) `plan:governance-backend-error`
 - [推理开关能力建模与 reasoning_tokens 采集实施计划(issue #5 + #6)](plans/2026-08-02-thinking-capability.md) `plan:2026-08-02-thinking-capability`
 - [调用方自定义维度实现计划(issue #11)](plans/issue11-caller-dimensions.md) `plan:issue11-caller-dimensions`