diff --git a/.github/workflows/sync-upstream.yml b/.github/workflows/sync-upstream.yml
deleted file mode 100644
index 386e92f46e..0000000000
--- a/.github/workflows/sync-upstream.yml
+++ /dev/null
@@ -1,71 +0,0 @@
-name: sync-upstream
-
-on:
-  schedule:
-    - cron: "0 6 * * 1" # Mondays 06:00 UTC
-  workflow_dispatch:
-    inputs:
-      ref:
-        description: "Upstream branch or tag to merge"
-        default: "dev"
-        required: false
-
-permissions:
-  contents: write
-  pull-requests: write
-
-jobs:
-  sync:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: main
-          fetch-depth: 0
-
-      - name: Fetch upstream
-        run: |
-          git remote add upstream https://github.com/anomalyco/opencode.git
-          git fetch upstream --tags
-
-      - name: Merge upstream
-        id: merge
-        run: |
-          REF="${{ github.event.inputs.ref || 'dev' }}"
-          TARGET=$(git rev-parse --verify --quiet "refs/remotes/upstream/$REF" || git rev-parse --verify "refs/tags/$REF^{commit}")
-          if git merge-base --is-ancestor "$TARGET" HEAD; then
-            echo "Already up to date with upstream/$REF ($TARGET)."
-            echo "status=uptodate" >> "$GITHUB_OUTPUT"
-            exit 0
-          fi
-          git config user.name "codev-sync"
-          git config user.email "github-actions[bot]@users.noreply.github.com"
-          BRANCH="sync-upstream-$(date +%Y%m%d)"
-          git checkout -b "$BRANCH"
-          if git merge --no-edit -m "chore: merge upstream $REF ($(git rev-parse --short "$TARGET"))" "$TARGET"; then
-            git push -u origin "$BRANCH"
-            echo "status=merged" >> "$GITHUB_OUTPUT"
-            echo "branch=$BRANCH" >> "$GITHUB_OUTPUT"
-            echo "target=$TARGET" >> "$GITHUB_OUTPUT"
-            echo "ref=$REF" >> "$GITHUB_OUTPUT"
-          else
-            echo "::error::Merge of upstream/$REF has conflicts. Resolve locally (see DIVERGENCES.md):"
-            git diff --name-only --diff-filter=U | sed 's/^/::error::  conflict: /'
-            exit 1
-          fi
-
-      - name: Open pull request
-        if: steps.merge.outputs.status == 'merged'
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          gh pr create \
-            --base main \
-            --head "${{ steps.merge.outputs.branch }}" \
-            --title "chore: merge upstream ${{ steps.merge.outputs.ref }}" \
-            --body "Automated merge of [upstream \`${{ steps.merge.outputs.ref }}\`](https://github.com/anomalyco/opencode/tree/${{ steps.merge.outputs.ref }}) at \`${{ steps.merge.outputs.target }}\`.
-
-          Review checklist:
-          - [ ] CI green (typecheck, tests)
-          - [ ] Divergences intact (see DIVERGENCES.md)
-          - [ ] \`bun.lock\` / generated files regenerated, not hand-merged"
diff --git a/DIVERGENCES.md b/DIVERGENCES.md
index 1a18832a70..257ff3213c 100644
--- a/DIVERGENCES.md
+++ b/DIVERGENCES.md
@@ -1,11 +1,12 @@
 # Divergences from upstream
 
-Every deliberate change to an upstream file is listed here. When a `sync-upstream` merge
-conflicts, this table tells you what the conflict is about and how to resolve it. If you
-edit an upstream file and it is not in this table, add it — an unlisted divergence is a bug.
+Every deliberate change to an upstream file is listed here. When an upstream sync patch
+(see README → Syncing with upstream) conflicts, this table tells you what the conflict is
+about and how to resolve it. If you edit an upstream file and it is not in this table,
+add it — an unlisted divergence is a bug.
 
-New files that upstream does not have (this file, `NOTICE`, `.github/workflows/sync-upstream.yml`,
-future `packages/codev-*`) never conflict and are not tracked here.
+New files that upstream does not have (this file, `NOTICE`, future `packages/codev-*`)
+never conflict and are not tracked here.
 
 ## Changed upstream files
 
diff --git a/README.md b/README.md
index 540b484ba0..f6219beaa0 100644
--- a/README.md
+++ b/README.md
@@ -40,20 +40,27 @@ Notes:
 
 ## Syncing with upstream
 
-A scheduled GitHub Action ([`sync-upstream.yml`](.github/workflows/sync-upstream.yml)) merges upstream `dev` into `main` weekly and opens a PR. It can also be run on demand (Actions → sync-upstream → Run workflow) against any upstream branch or tag.
-
-One-time repo setup for the action to open PRs: **Settings → Actions → General → Allow GitHub Actions to create and approve pull requests**.
-
-Manual sync:
+Syncing is manual and local — there is no CI workflow. `main` carries fork commits only
+(history was truncated; it shares no ancestry with upstream), so `git merge upstream/...`
+does not work. Instead, apply upstream's changes as a 3-way patch between release tags.
+The tag the fork is currently on is the `version` in `packages/opencode/package.json`.
 
 ```sh
-git fetch upstream --tags
+git fetch upstream --tags        # also brings in the blobs `git apply -3` needs
 git checkout -b sync-upstream main
-git merge upstream/dev
+# FROM = current version in packages/opencode/package.json; TO = target release
+git diff v<FROM> v<TO> --binary -- . ':(exclude)bun.lock' | git apply -3 --index
 # Conflicts in our own files: see DIVERGENCES.md for each file's resolution strategy.
-# Conflicts in bun.lock or generated code: regenerate (bun install / bun run generate), never hand-merge.
+# Files we deleted (locales, README translations): if the patch re-adds them, delete them again.
+bun install                      # regenerate bun.lock, never patch it
+bun turbo typecheck
+git commit -m "chore: sync upstream v<TO>"
 ```
 
+`git apply -3` leaves ordinary conflict markers where our divergences overlap upstream
+changes — the same conflict surface the old merge had. If a hunk fails outright, it is
+usually against a file we deleted or renamed; check DIVERGENCES.md before forcing it.
+
 ## Divergence policy
 
 Features go, in order of preference: