record the close of §5.9

docs/workspace-panel-todo.md

@@ -28,9 +28,9 @@ before deciding what to pick up next. Its conclusions in one paragraph:
   (§5.1), but inverted: the requirement is that closing a chat panel must _not_ destroy the agent;
   `normalizeLayout` as framework (§5.4); and the mobile-collapse decision (§6), which swings on one
   unanswered question.
-  **§5.9's first three are done** — the bag is a parsed identity (`dbe585f`) and the two file-browser
-  fields are deleted (`717580f`, `585f234`). What is left there is `promptPrefix` and the
-  constructed-in-two-places preview context.
+  **§5.9 is closed** (`dbe585f`, `717580f`, `585f234`, `d3922bd`, `ca046a3`) — the bag is a parsed
+  identity, the app-config fields are deleted or moved onto the app, and the inert context is built
+  once. Tier B is now panel lifecycle (§5.1), `normalizeLayout` (§5.4) and the mobile decision (§6).
 - **Tier C, orthogonal:** everything else — including **§5.2 (remounts) and §5.3 (drag-to-move), both
   large downgrades.** A panel is now a pointer to a server-side session, so a remount costs a replay, and
   the drag hazard is disarmed by resolving identity by name (`e588524` + `bc82086`).
@@ -490,9 +490,11 @@ All the same bug: an app guessing "am I being closed?" from an unmount, or payin
 `WorkspaceContext` is 18 fields, of which the framework itself reads none of the first six. Apps never
 touch the framework half, so the abstraction holds in one direction; the leak is entirely outbound.
 
-**Down to 16 as of 2026-08-07**, and the outbound half is now `workspace`, `cwd`, `root`, `promptPrefix`.
-Of those, `workspace` and `cwd` are genuinely the framework's to state — where the panel is and what
-directory it is over. `promptPrefix` is the one remaining courier job, and it is the next item.
+**§5.9 is closed as of 2026-08-07.** The context is 15 fields, and the outbound half is `workspace`,
+`cwd`, `root` — all three facts about *where the panel is*, which is the one thing a framework of this
+shape genuinely owes an app. Nothing left on it is an app's vocabulary: the file-browser pair is
+deleted, the chat's system prompt is a prop on the chat, and the key three apps used to parse is a
+parsed identity. The two hand-written copies of the inert half are one named constant.
 
 - [x] **Delete `initialFilePath` and `defaultFileSort`.** Declared `WorkspaceContext.ts:14-15`, plumbed
       through `WorkspaceView.tsx:19-20,30`, read only by
@@ -505,11 +507,17 @@ directory it is over. `promptPrefix` is the one remaining courier job, and it is
       the duplicate `DefaultSort` type in two files, and `useFileBrowserApp`'s `isolated` — which was
       `!!initialPath` and so had always been false. No behaviour changed at either level; both were
       already running on the defaults.
-- [ ] **Move `promptPrefix` onto the component, not the context.** `WorkspaceContext.ts:16` →
+- [x] **Move `promptPrefix` onto the component, not the context.** `WorkspaceContext.ts:16` →
       `Chat/ChatPanelWrapper.tsx:78` → `useEmbeddableChat.ts:107`. Set by `EmailScreen.tsx:53` and
       `BrowserScreen.tsx:35`, each a screen-local ~40-word system prompt. The framework is a courier for
       a string only one app understands, and the `components` prop already exists for exactly this —
       Email can supply a pre-configured chat by panel id.
+      **Done in `d3922bd`**, exactly that way: both screens put their own `ChatPanelWrapper` in
+      `components` under the chat panel's id and pass the prefix as a prop. `PanelSlot` prefers a
+      `components` entry over the registry for the *body* only, so the panel keeps its registry header —
+      the screens did not have to reproduce any chrome. `ChatPanelWrapper` is exported from the barrel
+      for it. The same prop came off `WorkspaceLayout`, where it had no callers at all: every settings
+      pane and job detail rendering through it had always been passing its chat panels `undefined`.
 - [x] **`dashboardId` is a bag whose _format_ three apps parse.** It is literally `workspace.key`
       (`WorkspaceView.tsx:163`). Consumers reverse-engineer meaning from its shape:
       `Chat/ChatPanelWrapper.tsx:51-56` does `dashboardId === 'email' || dashboardId === 'screens/email'`
@@ -531,11 +539,16 @@ directory it is over. `promptPrefix` is the one remaining courier job, and it is
       against a workspace with no row to hang it on), and `terminalStateKey` now takes the identity, so
       it can no longer nest a key inside itself. Seven tests in `workspace-identity.test.ts`, and the
       two live agents on `ws-layout-agent-mvp` were confirmed still addressable after the restart.
-- [ ] **`WorkspaceLayout.tsx:36` silently omits `root`** — apps inside a `DashboardPreview` fall through
+- [x] **`WorkspaceLayout.tsx:36` silently omits `root`** — apps inside a `DashboardPreview` fall through
       to the `createContext` defaults. (`initialFilePath` and `defaultFileSort` were on this list too and
       are now deleted; `workspace` is omitted there on purpose, since a preview is not a place an agent
       can be addressed.) Whatever survives the three items above should be constructed in one place, not
       twice by hand.
+      **Done in `ca046a3`.** The eleven interaction fields — everything a panel uses to rearrange the
+      workspace, plus the state those interactions run on — are one exported `inertInteraction`, spread
+      by `WorkspaceLayout` and by the `createContext` default. `root` stays omitted, and that is now a
+      stated decision rather than an oversight: it is only ever read when `cwd` is scoped, and no caller
+      of `WorkspaceLayout` passes a `cwd` at all, so there is nothing for it to be the root *of*.
 
 ### 5.10 Channel hygiene — _(found 2026-08-07)_
 
@@ -696,3 +709,16 @@ Low priority, but each line here is a line someone will read and believe.
       In the same pass, the two file-browser fields the context had grown were deleted, and with them
       the prop chain underneath that had no other caller. Net: the context is 16 fields from 18, and
       four dead parameters and a permanently-false flag are gone from the file browser.
+
+- [x] **The framework stopped carrying things only one app understands.** _(`d3922bd` + `ca046a3`,
+      branch `agent-coordination-mvp`)_ — the last two items of §5.9, and with them the section. A
+      screen's ~40-word system prompt used to travel screen → `WorkspaceView` → context →
+      `ChatPanelWrapper`, three of those four steps by a framework that has no idea what the string is.
+      It is now a prop on the chat panel the screen mounts itself through `components` — the prop that
+      already existed for supplying a panel's component, and which `PanelSlot` honours for the body
+      while still taking header and provider from the registry entry, so nothing about the panel's
+      chrome had to be reproduced.
+      The second half is the inert context: `WorkspaceLayout` and the `createContext` default had each
+      written out the same eleven switched-off fields by hand. `inertInteraction` names the idea once.
+      Net across all of §5.9: the context is 15 fields from 18, and everything still on it answers
+      "where is this panel" rather than "what should this panel do".