fix(pm): rewrite the REST-channel fact line as a session property carrying the gate-open readings

The fact line said 'session property' but still carried endpoint-shaped
residue: a single gate-open counterexample and a per-container framing.
Rewritten to the adjudicated shape — reachability is a property of the
session (the GitHub App session gate, snapshotted at session start), not
of any endpoint or seat type: the gate answers before the endpoint is
consulted, so a closed-gate 403 has zero discriminating power about any
specific endpoint; reads and writes fail together behind it; and four
independent gate-open dev containers measured the additive label POST at
200 (each confirmed by an independent GET read-back), with the channel
wider than labels — issue POST 201, comment writes, card/comment reads.
Probe method kept as the only safe reading; no channel is stated as an
unconditional guarantee. Line-neutral under the ratchet (314/314, all
lines within 120 bytes).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EXxTW8mvPBhoHxmyPZ63de

Author: claude

.claude/skills/pm-dispatch/references/platform-readings.md

@@ -86,16 +86,16 @@
 - **批量写 ~1 秒一发**:小时池之外还有**分钟级二级限流** —— GraphQL 端点 2,000 点/分、并发
   ≤100,官方指引:**变更类请求间停 ~1 秒**(mutation 按 5× 计)。双载体清标、批量重分诊这类
   把写挤在同一秒的扫动,会在小时池仍绿时撞上分钟墙(官方文档 2026-08-23 复核)。
-- **REST 可用性是会话属性,⛔ 不是全局事实 —— 开轮探一次,按班存档;探针必须
-  repo-scoped**:直连受会话级授权门钳制(会话起点快照),门关着 repo-scoped 路径**整类**回 403
-  `GitHub access is not enabled for this session`(⛔ 不是限流,重试改不了它),而 `/rate_limit` 照答 200
-  —— 它兼任不了通道探针;探针 = 一条真 repo-scoped 读。探针 403 后的单调用凭据判别见
-  `references/rest-channel.md`。**按班矩阵**:2026-08-25 两车道 5+ dev 席全被门拒(整类 403、读写同门
-  —— 加法标签 POST、评论 PATCH 同死 ⇒ 无评论编辑通道,更正=重发);2026-08-26 反例一席门
-  开,加法 POST 回 200;顶层席同窗分裂(两 403、一 200)⇒ **门态逐容器变**,⛔ 不据他席、他日
-  读数推本席,唯一安全读法即本行 repo-scoped 探针。**门关着时的降级梯**:① git 先行(「零成
-  本等价物」);② 公开仓 payload 档(下方「公开仓」条);③ MCP:search 定向一击、列表**单标
-  签**读全 + 本地求交(`labels` 是 OR,见 MCP 参数条);④ 等重置。
+- **REST 可达性是会话属性(GitHub App 会话门),⛔ 不是端点或席位类型的 —— 开轮探一次,按班
+  存档;探针必须 repo-scoped**:会话门(起点快照)先于端点应答,门关着 repo-scoped 路径**整类**回
+  403 `GitHub access is not enabled for this session`(⛔ 不是限流,重试无用;403 对具体端点零分辨力),而
+  `/rate_limit` 照答 200、兼任不了探针;探针 = 一条真 repo-scoped 读,403 后凭据判别见
+  `references/rest-channel.md`。**按班矩阵**:2026-08-25 两车道 5+ dev 席全被门拒(读写同门,评论 PATCH
+  同死 ⇒ 更正=重发);门开会话四个 dev 容器独立实测加法 POST 200(各独立 GET 读回),通道宽于
+  标签:issue POST 201、评论写、卡/评论读同通;顶层席同窗分裂(两 403、一 200)⇒ **门态逐会话
+  变**,⛔ 不据他席、他日读数推本席,唯一安全读法即本行探针。**门关着时的降级梯**:①
+  git 先行(「零成本等价物」);② 公开仓 payload 档(下方「公开仓」条);③ MCP:search 定向一
+  击、列表**单标签**读全 + 本地求交(`labels` 是 OR,见 MCP 参数条);④ 等重置。
 - **默认读序 git → payload → REST → MCP/GraphQL**(2026-08-23 策略翻转,2026-08-25 增补 payload 档;
   ⚠️ REST 档以**本班 repo-scoped 探针绿**为前提 —— 前提就住本行,403 会话改按降级梯读)。
   list/查重/卡与 PR 读/标签回读默认走容器 curl 的 REST 通道 —— App installation token,core