fix(§22/G-15): make the branch/edit/body subsystem three-tier aware (v0.53.0)

§22 migrated the READ/catalog path to the three-tier (project/collection)
model but the WRITE/branch/body subsystem still hardcoded the default
project's default collection — resolving every meta-resident entry to the
default content repo at rfcs/<slug>.md, ignoring the entry's project (its own
content repo) and collection (a <subfolder>/rfcs/ prefix). An entry outside
the default collection rendered a blank canonical body and every edit/PR/
body-write path hit the wrong file.

- New single resolver: projects.content_repo_for_collection() +
  projects.entry_location(config, cid, slug) -> (org, repo, md_path)
  (collection -> project -> content_repo + subfolder; falls back to the
  default repo for a legacy/unknown collection).
- Every entry write/read path resolves via it: api_branches (body GET + all
  branch write paths), api_prs (pr-draft/open/merge/withdraw/review/
  resolution-branch), api_graduation (graduate/claim/retire/unretire +
  orchestrator + state-flip), api.py mark-reviewed + idea-PR merge/decline/
  withdraw + proposal preview, api_metadata. bot.open_metadata_pr and
  bot.mark_entry_reviewed gained a file_path param. refresh_meta_branches,
  the webhook corpus-refresh dispatch, and the hygiene branch-delete now
  span every project's content repo, not just the default.
- New additive collection-scoped body-read routes:
  GET /api/projects/{pid}/collections/{cid}/rfcs/{slug}/main and
  .../branches/{branch} disambiguate a slug across collections (G-5) and read
  the entry's own repo. Slug-only routes kept (now collection-aware via the
  cached row). Frontend getRFCMain/getBranch take optional pid+cid; RFCView
  threads them (mirrors the v0.52.1 entry-detail fix).

No migration, no config change. Existing default-collection entries
unaffected. Tests: backend resolver + collection-scoped branch/body + graduate-
in-subfolder write path; frontend api unit. backend 677 / frontend 60 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/components/RFCView.jsx

@@ -221,8 +221,8 @@ export default function RFCView({ viewer }) {
     setSelection(null)
     setMode('discuss')
 
-    getRFCMain(slug).then(setMainView).catch(err => setError(err.message))
-    getBranch(slug, branchParam)
+    getRFCMain(slug, pid, cid).then(setMainView).catch(err => setError(err.message))
+    getBranch(slug, branchParam, pid, cid)
       .then(view => {
         setBranchView(view)
         setEditorContent(view.body || '')
@@ -231,7 +231,8 @@ export default function RFCView({ viewer }) {
         setChanges(view.changes || [])
       })
       .catch(err => setError(err.message))
-  }, [slug, branchParam, entry])
+    // §22/G-15: pid+cid scope the body reads; re-run if the collection changes.
+  }, [slug, branchParam, entry, pid, cid])
 
   // Load chat messages whenever the branch's main thread id resolves.
   useEffect(() => {
@@ -266,7 +267,7 @@ export default function RFCView({ viewer }) {
         paragraphCount: manualPending?.paragraphCount || 1,
       })
       if (!res.noop) {
-        const fresh = await getBranch(slug, branchParam)
+        const fresh = await getBranch(slug, branchParam, pid, cid)
         setBranchView(fresh)
         setChanges(fresh.changes || [])
         setPreviewContent(fresh.body || '')
@@ -408,7 +409,7 @@ export default function RFCView({ viewer }) {
         ))
       }
       // Re-pull authoritative state: changes have been materialized server-side.
-      const fresh = await getBranch(slug, branchParam)
+      const fresh = await getBranch(slug, branchParam, pid, cid)
       setChanges(fresh.changes || [])
       // If we're in discuss mode and the new turn produced pending AI changes,
       // surface them as discuss-mode buffered count.
@@ -447,7 +448,7 @@ export default function RFCView({ viewer }) {
         anchor_payload: { quote },
         label,
       })
-      const fresh = await getBranch(slug, branchParam)
+      const fresh = await getBranch(slug, branchParam, pid, cid)
       setBranchView(fresh)
       loadAllMessages(slug, branchParam, fresh.threads).then(setMessages)
     } catch (err) {
@@ -463,7 +464,7 @@ export default function RFCView({ viewer }) {
       // body. The proper tracked-changes overlay lives in Phase 3's
       // preview pane; with CM6 as the source editor there is no HTML
       // surface to inject `<span class="tracked-*">` into.
-      const fresh = await getBranch(slug, branchParam)
+      const fresh = await getBranch(slug, branchParam, pid, cid)
       setBranchView(fresh)
       setChanges(fresh.changes || [])
       setEditorContent(fresh.body || '')
@@ -477,7 +478,7 @@ export default function RFCView({ viewer }) {
   const handleDecline = useCallback(async (changeId) => {
     try {
       await apiDecline(slug, branchParam, changeId)
-      const fresh = await getBranch(slug, branchParam)
+      const fresh = await getBranch(slug, branchParam, pid, cid)
       setChanges(fresh.changes || [])
     } catch (err) {
       setError(err.message)
@@ -487,7 +488,7 @@ export default function RFCView({ viewer }) {
   const handleReask = useCallback(async (changeId) => {
     try {
       await reaskChange(slug, branchParam, changeId)
-      const fresh = await getBranch(slug, branchParam)
+      const fresh = await getBranch(slug, branchParam, pid, cid)
       setBranchView(fresh)
       setChanges(fresh.changes || [])
       loadAllMessages(slug, branchParam, fresh.threads).then(setMessages)
@@ -499,7 +500,7 @@ export default function RFCView({ viewer }) {
   const handleResolveThread = useCallback(async (threadId) => {
     try {
       await resolveThread(slug, branchParam, threadId)
-      const fresh = await getBranch(slug, branchParam)
+      const fresh = await getBranch(slug, branchParam, pid, cid)
       setBranchView(fresh)
       loadAllMessages(slug, branchParam, fresh.threads).then(setMessages)
     } catch (err) {
@@ -977,7 +978,7 @@ export default function RFCView({ viewer }) {
           current={branchView.visibility}
           onClose={() => setShowVisibility(false)}
           onSaved={async () => {
-            const fresh = await getBranch(slug, branchParam)
+            const fresh = await getBranch(slug, branchParam, pid, cid)
             setBranchView(fresh)
             setShowVisibility(false)
           }}
@@ -993,7 +994,7 @@ export default function RFCView({ viewer }) {
             setShowGraduateDialog(false)
             // The catalog row and the RFC view now reflect `active`.
             getRFC(pid, slug, cid).then(setEntry).catch(() => {})
-            getRFCMain(slug).then(setMainView).catch(() => {})
+            getRFCMain(slug, pid, cid).then(setMainView).catch(() => {})
           }}
         />
       )}
@@ -1016,7 +1017,7 @@ export default function RFCView({ viewer }) {
             setShowMetadataPane(false)
             // Refresh main view so the new open PR surfaces in the
             // breadcrumb meta count immediately.
-            getRFCMain(slug).then(setMainView).catch(() => {})
+            getRFCMain(slug, pid, cid).then(setMainView).catch(() => {})
             navigate(entryPrPath(pid, slug, prNumber))
           }}
         />