diff --git a/.mcp.json b/.mcp.json
index ed95798b..5ba95d7f 100644
--- a/.mcp.json
+++ b/.mcp.json
@@ -3,7 +3,8 @@
     "contentrain": {
       "command": "npx",
       "args": [
-        "@contentrain/mcp"
+        "-y",
+        "@contentrain/mcp@1.5.0"
       ]
     },
     "nuxt": {
diff --git a/CLAUDE.md b/CLAUDE.md
index aa08c1c8..a1b1592b 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -237,13 +237,23 @@ itself. Every save / delete op composes:
    (`status: 'draft'`, `updated_by: 'contentrain-mcp'`) with
    Studio's `autoPublish` + existing-status preservation +
    per-user `updated_by` semantics.
-4. `OverlayReader` + `buildContextChange` — wraps the plan changes
-   so `context.json` stats (entries per model, last-sync) reflect
-   the post-commit state, not the pre-change base branch.
-5. `provider.applyPlan({ branch, changes, message, author, base: 'contentrain' })`
+4. `provider.applyPlan({ branch, changes, message, author, base: 'contentrain' })`
    — atomic branch+commit via the GitHub Data API. `createBranch`
    is no longer called separately; `applyPlan` forks `base` when the
-   branch is missing.
+   branch is missing. **`context.json` is NOT part of `changes`** —
+   see the context.json invariant below.
+
+**`context.json` lifecycle (MCP 1.5.0 model)** — feature branches
+**never** carry `context.json`. Committing it per-save caused merge
+conflicts when parallel `cr/*` branches landed (each mutated the same
+file from the same base). Instead it is regenerated deterministically
+on the `contentrain` branch **after a merge**, in
+`branch-ops.ts:mergeBranch` → `regenerateContextOnContentrain`
+(`buildContextChange` over the merged tree + a dedicated
+`applyPlan` commit onto `contentrain`, best-effort). The seed
+`context.json` is still written once at `initProject` time. Brain cache
+and external readers only ever read it from `contentrain`, so post-merge
+regeneration is the single point it needs to be accurate.
 
 **Invariants to preserve** when touching this path:
 
@@ -251,9 +261,9 @@ itself. Every save / delete op composes:
   fork from it via `applyPlan`'s default `base`. `config.repository
   .default_branch` (`main` / `master`) is informational — never the
   fork point.
-- Post-change reads (for validation or context) go through
-  `OverlayReader(reader, pendingChanges)` — raw reader shows the
-  pre-change tree and will emit stale stats.
+- Never add `context.json` to a feature-branch `applyPlan`. Only
+  `initProject` (seed) and `regenerateContextOnContentrain` (post-merge,
+  on `contentrain`) may write it.
 - Studio's `pinReaderToContentrain` wrapper defaults ref to
   `CONTENTRAIN_BRANCH` for every MCP read (MCP's helpers call
   `reader.readFile(path)` without a ref).
@@ -262,7 +272,7 @@ itself. Every save / delete op composes:
 
 Medium:
 - Mobile shell: hamburger + slide-over (button exists, handler + drawer missing)
-- Branch health: no 80+ branch threshold, no auto-delete merged cr/* branches
+- Branch health: warn/block thresholds (default 50/80, config-driven via `branchWarnLimit`/`branchBlockLimit` since MCP 1.5.0) + merged `cr/*` auto-delete are implemented (`branch-health.ts`, `branch-cleanup.ts`). Remaining: surface health status in the UI
 - Brain cache: no GitHub webhook-triggered invalidation for external pushes (TTL-only, 10min)
 - MCP Cloud endpoint: `server/api/mcp/v1/[projectId]/[...].ts` awaits `@contentrain/mcp` `resolveProvider` callback (per-request provider resolution). Foundations (license entries, `mcp_cloud_keys` table, usage RPC) shipped in Faz S6 — route implementation pending.
 
diff --git a/package.json b/package.json
index 3c1a18f6..eb0b5053 100644
--- a/package.json
+++ b/package.json
@@ -45,9 +45,9 @@
   "dependencies": {
     "@anthropic-ai/sdk": "^0.80.0",
     "@aws-sdk/client-s3": "^3.1014.0",
-    "@contentrain/mcp": "1.4.0",
-    "@contentrain/query": "^5.1.2",
-    "@contentrain/types": "0.5.0",
+    "@contentrain/mcp": "1.5.0",
+    "@contentrain/query": "^6.0.0",
+    "@contentrain/types": "0.5.1",
     "@gitbeaker/rest": "^43.8.0",
     "@nuxt/eslint": "1.15.2",
     "@nuxt/image": "2.0.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0eb2fe66..db7a66da 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -15,14 +15,14 @@ importers:
         specifier: ^3.1014.0
         version: 3.1014.0
       '@contentrain/mcp':
-        specifier: 1.4.0
-        version: 1.4.0(@gitbeaker/rest@43.8.0)(@octokit/rest@22.0.1)
+        specifier: 1.5.0
+        version: 1.5.0(@gitbeaker/rest@43.8.0)(@octokit/rest@22.0.1)
       '@contentrain/query':
-        specifier: ^5.1.2
-        version: 5.1.2
+        specifier: ^6.0.0
+        version: 6.0.0
       '@contentrain/types':
-        specifier: 0.5.0
-        version: 0.5.0
+        specifier: 0.5.1
+        version: 0.5.1
       '@gitbeaker/rest':
         specifier: ^43.8.0
         version: 43.8.0
@@ -565,8 +565,8 @@ packages:
     resolution: {integrity: sha512-ZJoS8oSq2CAZEpc/YI9SulLrdiIyXeHb/OGqGrkUP6Q7YV+0ouNAa7GjqRdXeQPncHQIDz/jbCTlHScvYvO/gA==}
     engines: {node: '>=v18'}
 
-  '@contentrain/mcp@1.4.0':
-    resolution: {integrity: sha512-wIZVaquWzwxKnFtoIwaKThje7jMzQ37SDsBptxTVrTZxjef8LniYhYt/uMSQWy4pSDTGV6B9/jQrWnvoH40q5g==}
+  '@contentrain/mcp@1.5.0':
+    resolution: {integrity: sha512-PV+Pwb4o384Jb0joJP0eb2deLaZtWX8L346hBlapPVcGIuDUdzRhTXrI3jHV6b5wz+SiAF9Z0NUDI0mSdU95Sw==}
     hasBin: true
     peerDependencies:
       '@gitbeaker/rest': '>=43.0.0'
@@ -577,15 +577,12 @@ packages:
       '@octokit/rest':
         optional: true
 
-  '@contentrain/query@5.1.2':
-    resolution: {integrity: sha512-t4ogva5SYJXsRJNDhCpkDURoipmDlDEB6tsOIi697fuOpVKi60c9sKchdDYUEd7zNqcgx0d2dZGKae8qLfVMng==}
+  '@contentrain/query@6.0.0':
+    resolution: {integrity: sha512-qiTB/K4VPRO18TA1TlcEK1oPD7jEkPm6qYESyqnZLnE/heuBai2AS8xO3M32dflS89Zi3JXNaoIMI3c6hSHoQg==}
     hasBin: true
 
-  '@contentrain/types@0.4.0':
-    resolution: {integrity: sha512-saZ1qgdOfDmoNN2/KwUV59HEvcpOPtwdgZtmEWFFTxtJ1Cze1FZQCVElQfocikseNh5dE/rO/f/oVi/H1W/usw==}
-
-  '@contentrain/types@0.5.0':
-    resolution: {integrity: sha512-VWU2EERn3zVHYcDWyINqjiTM9p2kKl5H965qHRmWYlif+fWyzLUqsb7JzqOtvmGhsDSQfhT+8SLjs9duoLO6jg==}
+  '@contentrain/types@0.5.1':
+    resolution: {integrity: sha512-G8rlZFjtdSTVNVJVSsbO93pkmtVmxwXsRYSGmHK9q0Op672FEqSMHXNVCo+sF0+N/JYs+6kiW0GnsQOIV1v4Pg==}
 
   '@conventional-changelog/git-client@2.6.0':
     resolution: {integrity: sha512-T+uPDciKf0/ioNNDpMGc8FDsehJClZP0yR3Q5MN6wE/Y/1QZ7F+80OgznnTCOlMEG4AV0LvH2UJi3C/nBnaBUg==}
@@ -5478,11 +5475,6 @@ packages:
   sprintf-js@1.0.3:
     resolution: {integrity: sha512-D9cPgkvLlV3t3IzL0D0YLvGA9Ahk4PcvVwUbN0dSGr1aP0Nrt4AEnTUbuGvquEC0mA64Gqt1fzirlRs5ibXx8g==}
 
-  srvx@0.11.12:
-    resolution: {integrity: sha512-AQfrGqntqVPXgP03pvBDN1KyevHC+KmYVqb8vVf4N+aomQqdhaZxjvoVp+AOm4u6x+GgNQY3MVzAUIn+TqwkOA==}
-    engines: {node: '>=20.16.0'}
-    hasBin: true
-
   srvx@0.11.15:
     resolution: {integrity: sha512-iXsux0UcOjdvs0LCMa2Ws3WwcDUozA3JN3BquNXkaFPP7TpRqgunKdEgoZ/uwb1J6xaYHfxtz9Twlh6yzwM6Tg==}
     engines: {node: '>=20.16.0'}
@@ -7015,9 +7007,9 @@ snapshots:
       conventional-commits-parser: 6.3.0
       picocolors: 1.1.1
 
-  '@contentrain/mcp@1.4.0(@gitbeaker/rest@43.8.0)(@octokit/rest@22.0.1)':
+  '@contentrain/mcp@1.5.0(@gitbeaker/rest@43.8.0)(@octokit/rest@22.0.1)':
     dependencies:
-      '@contentrain/types': 0.5.0
+      '@contentrain/types': 0.5.1
       '@modelcontextprotocol/sdk': 1.27.1(zod@3.25.76)
       simple-git: 3.33.0
       typescript: 5.9.3
@@ -7032,13 +7024,11 @@ snapshots:
       - '@cfworker/json-schema'
       - supports-color
 
-  '@contentrain/query@5.1.2':
+  '@contentrain/query@6.0.0':
     dependencies:
-      '@contentrain/types': 0.4.0
+      '@contentrain/types': 0.5.1
 
-  '@contentrain/types@0.4.0': {}
-
-  '@contentrain/types@0.5.0': {}
+  '@contentrain/types@0.5.1': {}
 
   '@conventional-changelog/git-client@2.6.0(conventional-commits-parser@6.3.0)':
     dependencies:
@@ -7539,7 +7529,7 @@ snapshots:
       pkg-types: 2.3.0
       scule: 1.3.0
       semver: 7.7.4
-      srvx: 0.11.12
+      srvx: 0.11.15
       std-env: 3.10.0
       tinyclip: 0.1.12
       tinyexec: 1.1.1
@@ -12482,8 +12472,6 @@ snapshots:
 
   sprintf-js@1.0.3: {}
 
-  srvx@0.11.12: {}
-
   srvx@0.11.15: {}
 
   stable-hash-x@0.2.0: {}
diff --git a/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/cleanup.post.ts b/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/cleanup.post.ts
index 93ff69dd..c58c4c04 100644
--- a/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/cleanup.post.ts
+++ b/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/cleanup.post.ts
@@ -14,8 +14,8 @@ export default defineEventHandler(async (event) => {
   const db = useDatabaseProvider()
   await db.requireWorkspaceRole(session.accessToken, session.user.id, workspaceId, ['owner', 'admin'])
 
-  const { git } = await resolveProjectContext(workspaceId, projectId)
-  const report = await cleanupMergedBranches(git, projectId)
+  const { git, contentRoot } = await resolveProjectContext(workspaceId, projectId)
+  const report = await cleanupMergedBranches(git, projectId, undefined, contentRoot)
 
   return report
 })
diff --git a/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/health.get.ts b/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/health.get.ts
index 60b061db..57df275f 100644
--- a/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/health.get.ts
+++ b/server/api/workspaces/[workspaceId]/projects/[projectId]/branches/health.get.ts
@@ -15,6 +15,6 @@ export default defineEventHandler(async (event) => {
   const cached = await getHealthStatus(projectId)
   if (cached) return cached
 
-  const { git } = await resolveProjectContext(workspaceId, projectId)
-  return checkBranchHealth(git, projectId)
+  const { git, contentRoot } = await resolveProjectContext(workspaceId, projectId)
+  return checkBranchHealth(git, projectId, contentRoot)
 })
diff --git a/server/plugins/branch-cleanup.ts b/server/plugins/branch-cleanup.ts
index 73ead067..fa60515e 100644
--- a/server/plugins/branch-cleanup.ts
+++ b/server/plugins/branch-cleanup.ts
@@ -27,7 +27,7 @@ export default defineNitroPlugin((nitroApp) => {
 
 async function runBranchCleanup() {
   const db = useDatabaseProvider()
-  const projects = await db.listAllActiveProjects('id, repo_full_name, workspace_id')
+  const projects = await db.listAllActiveProjects('id, repo_full_name, workspace_id, content_root')
 
   for (const project of projects) {
     try {
@@ -44,7 +44,8 @@ async function runBranchCleanup() {
         repo,
       })
 
-      const report = await cleanupMergedBranches(git, project.id as string)
+      const contentRoot = normalizeContentRoot(project.content_root as string)
+      const report = await cleanupMergedBranches(git, project.id as string, undefined, contentRoot)
       if (report.deleted.length > 0) {
         // eslint-disable-next-line no-console
         console.info(`[branch-cleanup] ${owner}/${repo}: deleted ${report.deleted.length} merged branches, ${report.remaining} remaining`)
diff --git a/server/utils/branch-health.ts b/server/utils/branch-health.ts
index d33072ca..a018f73f 100644
--- a/server/utils/branch-health.ts
+++ b/server/utils/branch-health.ts
@@ -1,16 +1,24 @@
 /**
  * Branch health — monitors cr/* branch count and cleans up merged branches.
  *
- * Per git-architecture.md §8.2:
+ * Per git-architecture.md §8.2 (default thresholds):
  * - 0–49 unmerged cr/*: OK — operations proceed
  * - 50–79 unmerged cr/*: WARNING — operations proceed, user alerted
  * - 80+  unmerged cr/*: BLOCKED — new write operations rejected
  *
+ * As of @contentrain/mcp 1.5.0 the warn/block thresholds are configurable
+ * via `config.json` (`branchWarnLimit` / `branchBlockLimit`). Studio honors
+ * those when present and falls back to 50/80 otherwise — see
+ * {@link resolveBranchLimits}.
+ *
  * Merged branches are auto-deleted after branchRetention days (default 30).
  *
  * Cache: Redis when available (multi-instance safe), in-memory Map fallback.
  */
+import type { ContentrainConfig } from '@contentrain/types'
+import { CONTENTRAIN_BRANCH } from '@contentrain/types'
 import type { GitProvider } from '../providers/git'
+import { resolveConfigPath } from './content-paths'
 import { getRedis } from './redis'
 
 // ── Types ────────────────────────────────────────────
@@ -29,6 +37,12 @@ export interface CleanupReport {
   status: BranchHealthStatus
 }
 
+/** Resolved warn/block thresholds for the unmerged cr/* branch count. */
+export interface BranchLimits {
+  warn: number
+  block: number
+}
+
 // ── Constants ────────────────────────────────────────
 
 const WARNING_THRESHOLD = 50
@@ -105,11 +119,45 @@ export async function clearHealthCache(): Promise<void> {
   }
 }
 
+// ── Threshold resolution (config-driven, MCP 1.5.0) ──
+
+const DEFAULT_LIMITS: BranchLimits = { warn: WARNING_THRESHOLD, block: BLOCKED_THRESHOLD }
+
+/**
+ * Resolve branch-health thresholds. MCP 1.5.0 exposes `branchWarnLimit`
+ * (default 50) and `branchBlockLimit` (default 80) on `config.json`; Studio
+ * honors them so operators can tune limits without a code change. Reads
+ * config from the `contentrain` content branch.
+ *
+ * Falls back to the 50/80 defaults when `contentRoot` is omitted, the config
+ * is unreadable, or the fields are absent/non-numeric.
+ */
+export async function resolveBranchLimits(
+  git: GitProvider,
+  contentRoot?: string,
+): Promise<BranchLimits> {
+  if (contentRoot === undefined) return DEFAULT_LIMITS
+  try {
+    const raw = await git.readFile(resolveConfigPath({ contentRoot }), CONTENTRAIN_BRANCH)
+    const config = JSON.parse(raw) as ContentrainConfig
+    return {
+      warn: typeof config.branchWarnLimit === 'number' ? config.branchWarnLimit : WARNING_THRESHOLD,
+      block: typeof config.branchBlockLimit === 'number' ? config.branchBlockLimit : BLOCKED_THRESHOLD,
+    }
+  }
+  catch {
+    return DEFAULT_LIMITS
+  }
+}
+
 // ── Status calculation ───────────────────────────────
 
-export function calculateStatus(unmergedCount: number): BranchHealthStatus {
-  if (unmergedCount >= BLOCKED_THRESHOLD) return 'blocked'
-  if (unmergedCount >= WARNING_THRESHOLD) return 'warning'
+export function calculateStatus(
+  unmergedCount: number,
+  limits: BranchLimits = DEFAULT_LIMITS,
+): BranchHealthStatus {
+  if (unmergedCount >= limits.block) return 'blocked'
+  if (unmergedCount >= limits.warn) return 'warning'
   return 'ok'
 }
 
@@ -118,6 +166,7 @@ export function calculateStatus(unmergedCount: number): BranchHealthStatus {
 export async function checkBranchHealth(
   git: GitProvider,
   projectId: string,
+  contentRoot?: string,
 ): Promise<BranchHealthReport> {
   const branches = await git.listBranches('cr/')
   let unmergedCount = 0
@@ -127,8 +176,9 @@ export async function checkBranchHealth(
     if (!merged) unmergedCount++
   }
 
+  const limits = await resolveBranchLimits(git, contentRoot)
   const report: BranchHealthReport = {
-    status: calculateStatus(unmergedCount),
+    status: calculateStatus(unmergedCount, limits),
     unmergedCount,
     lastChecked: new Date().toISOString(),
   }
@@ -142,6 +192,7 @@ export async function cleanupMergedBranches(
   git: GitProvider,
   projectId: string,
   retentionDays: number = DEFAULT_RETENTION_DAYS,
+  contentRoot?: string,
 ): Promise<CleanupReport> {
   const branches = await git.listBranches('cr/')
   const deleted: string[] = []
@@ -165,10 +216,11 @@ export async function cleanupMergedBranches(
   }
 
   const remaining = branches.length - deleted.length
+  const limits = await resolveBranchLimits(git, contentRoot)
   const report: CleanupReport = {
     deleted,
     remaining,
-    status: calculateStatus(remaining),
+    status: calculateStatus(remaining, limits),
   }
 
   // Update cache after cleanup
diff --git a/server/utils/content-engine/branch-ops.ts b/server/utils/content-engine/branch-ops.ts
index 60d89681..3340d034 100644
--- a/server/utils/content-engine/branch-ops.ts
+++ b/server/utils/content-engine/branch-ops.ts
@@ -1,5 +1,7 @@
+import { buildContextChange } from '@contentrain/mcp/core/context'
 import type { Branch, EngineInternalContext, MergeResult } from './types'
-import { BRANCH_PREFIX, CONTENT_BRANCH } from './types'
+import { BOT_AUTHOR, BRANCH_PREFIX, CONTENT_BRANCH } from './types'
+import { pinReaderToContentrain } from './helpers'
 
 /**
  * Ensure the dedicated `contentrain` branch exists and is synced with main.
@@ -89,6 +91,11 @@ export async function mergeBranch(ctx: EngineInternalContext, branch: string): P
     // Branch may have been auto-deleted
   }
 
+  // Regenerate context.json on contentrain now that the content has
+  // landed — feature branches no longer carry it (MCP 1.5.0 model), so
+  // it is rebuilt here from the merged tree before main is advanced.
+  await regenerateContextOnContentrain(ctx, branch)
+
   // Step 2: advance contentrain -> main
   const defaultBranch = await ctx.git.getDefaultBranch()
   try {
@@ -116,3 +123,59 @@ export async function mergeBranch(ctx: EngineInternalContext, branch: string): P
 export async function rejectBranch(ctx: EngineInternalContext, branch: string): Promise<void> {
   await ctx.git.deleteBranch(branch)
 }
+
+/**
+ * Regenerate `context.json` deterministically on the `contentrain` branch
+ * after a feature branch lands (MCP 1.5.0 model).
+ *
+ * Feature branches no longer carry `context.json`, which removes the
+ * merge-conflict surface when parallel `cr/*` saves land. Instead the file
+ * is rebuilt here from the merged `contentrain` tree so its stats
+ * (model / entry counts) reflect post-merge reality. The brain cache and
+ * external readers only ever read `context.json` from `contentrain`, so
+ * this is the single point where it needs to be accurate.
+ *
+ * Best-effort: a failure (transient git error, or a concurrent
+ * regeneration losing the non-fast-forward ref update) is swallowed — the
+ * next merge regenerates it correctly.
+ */
+async function regenerateContextOnContentrain(
+  ctx: EngineInternalContext,
+  mergedBranch: string,
+): Promise<void> {
+  try {
+    const reader = pinReaderToContentrain(ctx.git)
+    const contextChange = await buildContextChange(reader, parseMergeOperation(mergedBranch), 'mcp-studio')
+
+    // Skip an empty commit when the merged tree already carries an
+    // identical context.json.
+    try {
+      const current = await reader.readFile(contextChange.path)
+      if (current === contextChange.content) return
+    }
+    catch { /* no existing context.json — fall through and write it */ }
+
+    await ctx.git.applyPlan({
+      branch: CONTENT_BRANCH,
+      changes: [contextChange],
+      message: 'contentrain: regenerate context.json',
+      author: BOT_AUTHOR,
+      base: CONTENT_BRANCH,
+    })
+  }
+  catch {
+    // Best-effort: context.json self-heals on the next merge.
+  }
+}
+
+/**
+ * Derive the `context.json` lastOperation from a merged `cr/*` branch name.
+ * Format: `cr/{scope}/{target}[/{locale}]/{timestamp}-{suffix}`.
+ */
+function parseMergeOperation(branch: string): { tool: string, model: string, locale?: string } {
+  const parts = branch.split('/')
+  // cr / scope / target / [locale] / timestamp-suffix
+  const model = parts[2] ?? ''
+  const locale = parts.length >= 5 ? parts[3] : undefined
+  return { tool: 'merge', model, locale }
+}
diff --git a/server/utils/content-engine/delete-content.ts b/server/utils/content-engine/delete-content.ts
index 77a5388b..6a30f983 100644
--- a/server/utils/content-engine/delete-content.ts
+++ b/server/utils/content-engine/delete-content.ts
@@ -1,6 +1,5 @@
 import type { FileChange, ModelDefinition, RepoReader } from '@contentrain/types'
 import { CONTENTRAIN_BRANCH as MCP_CONTENTRAIN_BRANCH } from '@contentrain/types'
-import { buildContextChange } from '@contentrain/mcp/core/context'
 import { planContentDelete } from '@contentrain/mcp/core/ops'
 import { OverlayReader } from '@contentrain/mcp/core/overlay-reader'
 import type { EngineInternalContext, WriteResult } from './types'
@@ -43,14 +42,9 @@ export async function deleteContent(
 
   const aggregatedChanges = [...changesByPath.values()]
 
-  const overlay = new OverlayReader(reader, aggregatedChanges)
-  const contextChange = await buildContextChange(
-    overlay,
-    { tool: 'delete_content', model: modelId, locale, entries: entryIds },
-    'mcp-studio',
-  )
-
-  const allChanges: FileChange[] = [...aggregatedChanges, contextChange]
+  // context.json is regenerated on `contentrain` post-merge (MCP 1.5.0
+  // model), not committed on the feature branch.
+  const allChanges: FileChange[] = [...aggregatedChanges]
     .toSorted((a, b) => a.path.localeCompare(b.path))
 
   const { branchName } = await createFeatureBranch(ctx, 'content', modelId, locale)
diff --git a/server/utils/content-engine/helpers.ts b/server/utils/content-engine/helpers.ts
index 5c160071..a044eae9 100644
--- a/server/utils/content-engine/helpers.ts
+++ b/server/utils/content-engine/helpers.ts
@@ -36,7 +36,7 @@ export async function createFeatureBranch(
 ): Promise<{ branchName: string, healthWarning?: string }> {
   if (ctx.projectId) {
     const cached = await getHealthStatus(ctx.projectId)
-    const health = cached ?? await checkBranchHealth(ctx.git, ctx.projectId)
+    const health = cached ?? await checkBranchHealth(ctx.git, ctx.projectId, ctx.pathCtx.contentRoot)
 
     if (health.status === 'blocked') {
       throw createError({
diff --git a/server/utils/content-engine/save-content.ts b/server/utils/content-engine/save-content.ts
index f81909b0..40637832 100644
--- a/server/utils/content-engine/save-content.ts
+++ b/server/utils/content-engine/save-content.ts
@@ -1,8 +1,6 @@
 import type { ContentrainConfig, FileChange, ModelDefinition, ValidationResult, Vocabulary } from '@contentrain/types'
 import { CONTENTRAIN_BRANCH as MCP_CONTENTRAIN_BRANCH } from '@contentrain/types'
-import { buildContextChange } from '@contentrain/mcp/core/context'
 import { planContentSave } from '@contentrain/mcp/core/ops'
-import { OverlayReader } from '@contentrain/mcp/core/overlay-reader'
 import type { ValidationContext } from '../content-validation'
 import type { EngineInternalContext, WriteResult } from './types'
 import { BOT_AUTHOR, CONTENT_BRANCH } from './types'
@@ -26,9 +24,8 @@ import {
  * - feature-branch lifecycle (`cr/*` name generation, health check)
  * - commit + diff bookkeeping for the `WriteResult` return shape
  *
- * `OverlayReader` is wrapped around the pinned reader so the committed
- * `context.json` reflects post-commit stats (see `.internal/refactor/
- * 02-studio-handoff.md` Faz S2.1 — Phase 10 tuzakları).
+ * `context.json` is not committed here — it is regenerated on
+ * `contentrain` post-merge (MCP 1.5.0 model; see `branch-ops.ts`).
  */
 export async function saveContent(
   ctx: EngineInternalContext,
@@ -164,19 +161,11 @@ export async function saveContent(
     userEmail,
   })
 
-  const overlay = new OverlayReader(reader, patchedChanges)
-  const contextChange = await buildContextChange(
-    overlay,
-    {
-      tool: 'save_content',
-      model: modelId,
-      locale,
-      entries: modelDef.kind === 'collection' ? touchedIds : undefined,
-    },
-    'mcp-studio',
-  )
-
-  const allChanges: FileChange[] = [...patchedChanges, contextChange]
+  // context.json is NOT committed on feature branches (MCP 1.5.0 model):
+  // it is regenerated deterministically on `contentrain` post-merge so
+  // parallel saves cannot conflict on it. See `regenerateContextOnContentrain`
+  // in `branch-ops.ts`.
+  const allChanges: FileChange[] = [...patchedChanges]
     .toSorted((a, b) => a.path.localeCompare(b.path))
 
   const { branchName } = await createFeatureBranch(ctx, 'content', modelId, locale)
diff --git a/server/utils/content-engine/save-document.ts b/server/utils/content-engine/save-document.ts
index 28d84c27..7f5e9481 100644
--- a/server/utils/content-engine/save-document.ts
+++ b/server/utils/content-engine/save-document.ts
@@ -1,8 +1,6 @@
 import type { ContentrainConfig, FileChange, ModelDefinition, Vocabulary } from '@contentrain/types'
 import { CONTENTRAIN_BRANCH as MCP_CONTENTRAIN_BRANCH, validateSlug } from '@contentrain/types'
-import { buildContextChange } from '@contentrain/mcp/core/context'
 import { planContentSave } from '@contentrain/mcp/core/ops'
-import { OverlayReader } from '@contentrain/mcp/core/overlay-reader'
 import type { EngineInternalContext, WriteResult } from './types'
 import { BOT_AUTHOR, CONTENT_BRANCH } from './types'
 import { applyStudioMetaOverrides, pinReaderToContentrain, createFeatureBranch } from './helpers'
@@ -12,9 +10,8 @@ import { applyStudioMetaOverrides, pinReaderToContentrain, createFeatureBranch }
  *
  * Delegates markdown serialization + path resolution to
  * `planContentSave` (document kind); Studio overrides meta with its
- * own status + user-email logic and wires `OverlayReader` around the
- * pending changes so the committed `context.json` reflects post-commit
- * stats.
+ * own status + user-email logic. `context.json` is not touched here —
+ * it is regenerated on `contentrain` post-merge (MCP 1.5.0 model).
  */
 export async function saveDocument(
   ctx: EngineInternalContext,
@@ -104,14 +101,9 @@ export async function saveDocument(
     userEmail,
   })
 
-  const overlay = new OverlayReader(reader, patchedChanges)
-  const contextChange = await buildContextChange(
-    overlay,
-    { tool: 'save_content', model: modelId, locale, entries: [safeSlug] },
-    'mcp-studio',
-  )
-
-  const allChanges: FileChange[] = [...patchedChanges, contextChange]
+  // context.json is regenerated on `contentrain` post-merge, not committed
+  // here (MCP 1.5.0 model — see `branch-ops.ts`).
+  const allChanges: FileChange[] = [...patchedChanges]
     .toSorted((a, b) => a.path.localeCompare(b.path))
 
   const { branchName } = await createFeatureBranch(ctx, 'content', modelId, locale)
diff --git a/server/utils/content-engine/save-model.ts b/server/utils/content-engine/save-model.ts
index f818a161..0ee156ff 100644
--- a/server/utils/content-engine/save-model.ts
+++ b/server/utils/content-engine/save-model.ts
@@ -1,8 +1,6 @@
 import type { ContentrainConfig, FileChange, ModelDefinition } from '@contentrain/types'
 import { CONTENTRAIN_BRANCH as MCP_CONTENTRAIN_BRANCH } from '@contentrain/types'
-import { buildContextChange } from '@contentrain/mcp/core/context'
 import { planModelSave } from '@contentrain/mcp/core/ops'
-import { OverlayReader } from '@contentrain/mcp/core/overlay-reader'
 import type { EngineInternalContext, WriteResult } from './types'
 import { BOT_AUTHOR, CONTENT_BRANCH } from './types'
 import { pinReaderToContentrain, createFeatureBranch } from './helpers'
@@ -13,8 +11,8 @@ import { pinReaderToContentrain, createFeatureBranch } from './helpers'
  * Schema validation (Studio-owned today, pending S3 unification with MCP)
  * runs first; if it passes, file assembly is delegated to
  * `planModelSave` — it writes `.contentrain/models/{id}.json` in
- * canonical form. Studio adds the `context.json` change on top via
- * `buildContextChange` wrapped in an `OverlayReader`.
+ * canonical form. `context.json` is regenerated on `contentrain`
+ * post-merge (MCP 1.5.0 model), not committed on the feature branch.
  */
 export async function saveModel(
   ctx: EngineInternalContext,
@@ -82,14 +80,7 @@ export async function saveModel(
     }
   }
 
-  const overlay = new OverlayReader(reader, plan.changes)
-  const contextChange = await buildContextChange(
-    overlay,
-    { tool: 'save_model', model: definition.id, locale: '' },
-    'mcp-studio',
-  )
-
-  const allChanges: FileChange[] = [...plan.changes, contextChange]
+  const allChanges: FileChange[] = [...plan.changes]
     .toSorted((a, b) => a.path.localeCompare(b.path))
 
   const { branchName } = await createFeatureBranch(ctx, 'model', definition.id)
diff --git a/server/utils/content-engine/update-status.ts b/server/utils/content-engine/update-status.ts
index 478ed49a..694448c0 100644
--- a/server/utils/content-engine/update-status.ts
+++ b/server/utils/content-engine/update-status.ts
@@ -1,7 +1,5 @@
 import type { EntryMeta, FileChange, ModelDefinition } from '@contentrain/types'
 import { canonicalStringify, CONTENTRAIN_BRANCH as MCP_CONTENTRAIN_BRANCH } from '@contentrain/types'
-import { buildContextChange } from '@contentrain/mcp/core/context'
-import { OverlayReader } from '@contentrain/mcp/core/overlay-reader'
 import type { EngineInternalContext, WriteResult } from './types'
 import { BOT_AUTHOR, CONTENT_BRANCH } from './types'
 import { pinReaderToContentrain, createFeatureBranch } from './helpers'
@@ -35,7 +33,7 @@ export async function updateEntryStatus(
 
   for (const entryId of entryIds) {
     existingMeta[entryId] = {
-      ...(existingMeta[entryId] ?? {}),
+      ...existingMeta[entryId],
       status,
       updated_by: userEmail,
     } as EntryMeta
@@ -43,15 +41,9 @@ export async function updateEntryStatus(
 
   const metaChange: FileChange = { path: metaPath, content: canonicalStringify(existingMeta) }
 
-  const overlay = new OverlayReader(reader, [metaChange])
-  const contextChange = await buildContextChange(
-    overlay,
-    { tool: 'update_status', model: modelId, locale, entries: entryIds },
-    'mcp-studio',
-  )
-
-  const allChanges: FileChange[] = [metaChange, contextChange]
-    .toSorted((a, b) => a.path.localeCompare(b.path))
+  // context.json is regenerated on `contentrain` post-merge (MCP 1.5.0
+  // model), not committed on the feature branch.
+  const allChanges: FileChange[] = [metaChange]
 
   const { branchName } = await createFeatureBranch(ctx, 'content', modelId, locale)
 
@@ -135,14 +127,9 @@ export async function copyLocale(
     { path: targetMetaPath, content: metaContent },
   ]
 
-  const overlay = new OverlayReader(reader, copyChanges)
-  const contextChange = await buildContextChange(
-    overlay,
-    { tool: 'copy_locale', model: modelId, locale: toLocale },
-    'mcp-studio',
-  )
-
-  const allChanges: FileChange[] = [...copyChanges, contextChange]
+  // context.json is regenerated on `contentrain` post-merge (MCP 1.5.0
+  // model), not committed on the feature branch.
+  const allChanges: FileChange[] = [...copyChanges]
     .toSorted((a, b) => a.path.localeCompare(b.path))
 
   const { branchName } = await createFeatureBranch(ctx, 'content', modelId)
diff --git a/tests/unit/content-engine.test.ts b/tests/unit/content-engine.test.ts
index f4399e29..1ce737a1 100644
--- a/tests/unit/content-engine.test.ts
+++ b/tests/unit/content-engine.test.ts
@@ -102,6 +102,31 @@ describe('content engine', () => {
     })
   })
 
+  it('regenerates context.json on contentrain after a successful merge', async () => {
+    const applyPlan = vi.fn().mockResolvedValue(defaultCommit)
+    const git = createGitProvider({
+      getDefaultBranch: vi.fn().mockResolvedValue('main'),
+      mergeBranch: vi.fn().mockResolvedValue({ merged: true, sha: 'merge-sha', pullRequestUrl: null }),
+      deleteBranch: vi.fn().mockResolvedValue(undefined),
+      applyPlan,
+    })
+    const engine = createContentEngine({ git, contentRoot: '' })
+
+    await engine.mergeBranch('cr/content/faq/en/1234567890-abcd')
+
+    // Feature branches no longer carry context.json (MCP 1.5.0 model); it
+    // is rebuilt on contentrain post-merge via a dedicated commit.
+    expect(applyPlan).toHaveBeenCalledWith(
+      expect.objectContaining({
+        branch: 'contentrain',
+        base: 'contentrain',
+        changes: expect.arrayContaining([
+          expect.objectContaining({ path: '.contentrain/context.json' }),
+        ]),
+      }),
+    )
+  })
+
   it('falls back to PR creation when branch protection blocks step 2 merge', async () => {
     const git = createGitProvider({
       getDefaultBranch: vi.fn().mockResolvedValue('main'),
@@ -264,7 +289,7 @@ describe('content engine', () => {
     expect(result.validation.errors[0]?.message).toBe('Model does not support i18n')
   })
 
-  it('saves model definitions and emits context change', async () => {
+  it('saves model definitions without committing context.json on the feature branch', async () => {
     const applyPlan = vi.fn().mockResolvedValue(defaultCommit)
     const git = createGitProvider({
       readFile: vi.fn(async (path: string) => {
@@ -299,10 +324,14 @@ describe('content engine', () => {
         base: 'contentrain',
         changes: expect.arrayContaining([
           expect.objectContaining({ path: '.contentrain/models/authors.json' }),
-          expect.objectContaining({ path: '.contentrain/context.json' }),
         ]),
       }),
     )
+
+    // context.json is regenerated on contentrain post-merge (MCP 1.5.0
+    // model), never committed on the feature branch.
+    const call = applyPlan.mock.calls[0]?.[0] as { changes: Array<{ path: string }> }
+    expect(call.changes.some(c => c.path.endsWith('context.json'))).toBe(false)
   })
 
   it('initializes a project with config, models, content, and meta files', async () => {