diff --git a/.github/actions/sync-fork-checkpoints/action.yml b/.github/actions/sync-fork-checkpoints/action.yml
new file mode 100644
index 000000000..0c84f81fa
--- /dev/null
+++ b/.github/actions/sync-fork-checkpoints/action.yml
@@ -0,0 +1,191 @@
+name: 'Sync Fork Checkpoints'
+description: 'Import Entire session checkpoint data from a fork after a PR is merged'
+
+inputs:
+  token:
+    description: 'GitHub token with contents:write permission. Defaults to GITHUB_TOKEN.'
+    required: false
+    default: ${{ github.token }}
+
+outputs:
+  imported_count:
+    description: 'Number of checkpoint commits cherry-picked'
+    value: ${{ steps.sync.outputs.imported_count }}
+  synced:
+    description: 'Whether any checkpoints were synced (true/false)'
+    value: ${{ steps.sync.outputs.synced }}
+
+runs:
+  using: 'composite'
+  steps:
+    - name: Sync fork checkpoints
+      id: sync
+      shell: bash
+      env:
+        GH_TOKEN: ${{ inputs.token }}
+        REPO: ${{ github.repository }}
+        FORK_URL: ${{ github.event.pull_request.head.repo.clone_url }}
+        FORK_FULL_NAME: ${{ github.event.pull_request.head.repo.full_name }}
+        IS_FORK: ${{ github.event.pull_request.head.repo.fork }}
+        MERGE_SHA: ${{ github.event.pull_request.merge_commit_sha }}
+        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        PR_NUMBER: ${{ github.event.pull_request.number }}
+      run: |
+        set -euo pipefail
+
+        BRANCH="entire/checkpoints/v1"
+        ORIGIN_URL="https://x-access-token:${GH_TOKEN}@github.com/${REPO}.git"
+
+        echo "synced=false" >> "$GITHUB_OUTPUT"
+        echo "imported_count=0" >> "$GITHUB_OUTPUT"
+
+        # --- Guard: only run for fork PRs ---
+        if [ "$IS_FORK" != "true" ]; then
+          echo "PR is not from a fork. Skipping."
+          exit 0
+        fi
+
+        # --- Set up a minimal repo (no full checkout, only checkpoints branch) ---
+        WORKDIR=$(mktemp -d)
+        cd "$WORKDIR"
+        git init
+        git remote add origin "$ORIGIN_URL"
+
+        # Fetch only the merge range commits (for reading trailers)
+        git fetch origin "$MERGE_SHA" --depth=100 2>/dev/null || true
+        git fetch origin "$BASE_SHA" --depth=100 2>/dev/null || true
+
+        # --- Step 1: Find checkpoint IDs in merged commits ---
+        echo "Looking for Entire-Checkpoint trailers in ${BASE_SHA:0:7}..${MERGE_SHA:0:7}"
+
+        CHECKPOINT_IDS=$(git log --format='%(trailers:key=Entire-Checkpoint,valueonly)' \
+          "${BASE_SHA}..${MERGE_SHA}" 2>/dev/null \
+          | sed 's/^[[:space:]]*//;s/[[:space:]]*$//' \
+          | grep -v '^$' | sort -u || true)
+
+        # Fallback: check original PR commits (handles squash merges that drop trailers)
+        if [ -z "$CHECKPOINT_IDS" ]; then
+          echo "No trailers in merge range. Checking original PR commits..."
+          git fetch "$FORK_URL" "$HEAD_SHA" --depth=50 2>/dev/null || true
+          CHECKPOINT_IDS=$(git log --format='%(trailers:key=Entire-Checkpoint,valueonly)' \
+            "${BASE_SHA}..${HEAD_SHA}" 2>/dev/null \
+            | sed 's/^[[:space:]]*//;s/[[:space:]]*$//' \
+            | grep -v '^$' | sort -u || true)
+        fi
+
+        if [ -z "$CHECKPOINT_IDS" ]; then
+          echo "No Entire-Checkpoint trailers found. Nothing to sync."
+          exit 0
+        fi
+
+        echo "Found checkpoint IDs:"
+        echo "$CHECKPOINT_IDS"
+        echo ""
+
+        # --- Step 2: Fetch fork's checkpoints branch ---
+        echo "Fetching $BRANCH from fork ($FORK_FULL_NAME)..."
+        if ! git fetch "$FORK_URL" "$BRANCH" 2>/dev/null; then
+          echo "Fork has no $BRANCH branch. Nothing to sync."
+          exit 0
+        fi
+        FORK_REF=$(git rev-parse FETCH_HEAD)
+        echo "Fork's $BRANCH is at ${FORK_REF:0:7}"
+
+        # --- Step 3: Validate checkpoint IDs ---
+        VALID_IDS=()
+        for ID in $CHECKPOINT_IDS; do
+          if echo "$ID" | grep -qE '^[0-9a-f]{12}$'; then
+            VALID_IDS+=("$ID")
+          else
+            echo "  Skipping invalid checkpoint ID: $ID"
+          fi
+        done
+
+        if [ ${#VALID_IDS[@]} -eq 0 ]; then
+          echo "No valid checkpoint IDs found. Nothing to sync."
+          exit 0
+        fi
+
+        # --- Step 4: Find matching commits on fork's checkpoints branch ---
+        GREP_PATTERN=$(printf '%s\n' "${VALID_IDS[@]}" | paste -sd '|' -)
+
+        # Fetch upstream's checkpoints branch to determine fork-only commits
+        git fetch origin "$BRANCH" 2>/dev/null || true
+
+        if git rev-parse --verify "refs/remotes/origin/$BRANCH" >/dev/null 2>&1; then
+          FORK_RANGE="origin/${BRANCH}..${FORK_REF}"
+        else
+          FORK_RANGE="${FORK_REF}"
+        fi
+
+        # Find commits referencing our checkpoint IDs, in chronological order
+        COMMITS=$(git log --reverse --format='%H' --extended-regexp \
+          --grep="(${GREP_PATTERN})" "$FORK_RANGE" 2>/dev/null || true)
+
+        if [ -z "$COMMITS" ]; then
+          echo "No matching commits found on fork's $BRANCH. Nothing to sync."
+          exit 0
+        fi
+
+        COMMIT_COUNT=$(echo "$COMMITS" | wc -l | tr -d ' ')
+        echo "Found $COMMIT_COUNT commit(s) to cherry-pick"
+
+        # --- Step 5: Set up git identity ---
+        git config user.name "github-actions[bot]"
+        git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+        # --- Step 6: Check out or create the local checkpoints branch ---
+        if git rev-parse --verify "refs/remotes/origin/$BRANCH" >/dev/null 2>&1; then
+          echo "Checking out existing $BRANCH..."
+          git checkout -B "$BRANCH" "origin/$BRANCH"
+        else
+          echo "Creating new orphan branch $BRANCH..."
+          git checkout --orphan "$BRANCH"
+          git rm -rf . 2>/dev/null || true
+          git commit --allow-empty -m "Initialize $BRANCH"
+        fi
+
+        # --- Step 7: Cherry-pick each commit (preserves messages, trailers, authorship) ---
+        IMPORTED=0
+        while IFS= read -r COMMIT; do
+          [ -z "$COMMIT" ] && continue
+          SUBJECT=$(git log -1 --format='%s' "$COMMIT")
+          echo "  Cherry-picking: $SUBJECT (${COMMIT:0:7})"
+          if git cherry-pick "$COMMIT" --no-edit; then
+            IMPORTED=$((IMPORTED + 1))
+          else
+            git cherry-pick --abort 2>/dev/null || true
+            echo "  Warning: failed to cherry-pick ${COMMIT:0:7}, skipping"
+          fi
+        done <<< "$COMMITS"
+
+        if [ "$IMPORTED" -eq 0 ]; then
+          echo "No commits were successfully cherry-picked. Nothing to sync."
+          exit 0
+        fi
+
+        # --- Step 8: Push only the checkpoints branch (with retry for concurrent merges) ---
+        MAX_RETRIES=3
+        for ATTEMPT in $(seq 1 $MAX_RETRIES); do
+          if git push origin "$BRANCH"; then
+            echo ""
+            echo "Successfully cherry-picked ${IMPORTED} commit(s) from PR #${PR_NUMBER}"
+            echo "synced=true" >> "$GITHUB_OUTPUT"
+            echo "imported_count=${IMPORTED}" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          if [ "$ATTEMPT" -lt "$MAX_RETRIES" ]; then
+            echo "Push failed (attempt $ATTEMPT/$MAX_RETRIES). Rebasing on remote..."
+            git fetch origin "$BRANCH"
+            git rebase "origin/$BRANCH" || {
+              echo "Rebase failed, trying merge..."
+              git rebase --abort 2>/dev/null || true
+              git merge "origin/$BRANCH" --no-edit
+            }
+          fi
+        done
+
+        echo "::warning::Failed to push checkpoints after $MAX_RETRIES attempts"
+        exit 1
diff --git a/.github/workflows/sync-fork-checkpoints.yml b/.github/workflows/sync-fork-checkpoints.yml
new file mode 100644
index 000000000..78760758d
--- /dev/null
+++ b/.github/workflows/sync-fork-checkpoints.yml
@@ -0,0 +1,32 @@
+# Sync Entire session checkpoints from fork PRs.
+#
+# When a PR from a fork is merged, this workflow imports the checkpoint data
+# (session transcripts, prompts, context) from the fork's entire/checkpoints/v1
+# branch into the upstream repo's entire/checkpoints/v1 branch.
+#
+# This enables the full Entire session history to be preserved even when
+# contributors work from forks without push access to upstream.
+#
+# How it works:
+#   1. Finds Entire-Checkpoint trailers in the merged commits
+#   2. Fetches the fork's entire/checkpoints/v1 branch
+#   3. Selectively imports only the referenced checkpoint directories
+#   4. Pushes the updated checkpoints branch to upstream
+
+name: Sync Fork Checkpoints
+
+on:
+  pull_request_target:
+    types: [closed]
+
+permissions:
+  contents: write
+
+jobs:
+  sync-checkpoints:
+    if: >-
+      github.event.pull_request.merged == true &&
+      github.event.pull_request.head.repo.fork == true
+    runs-on: ubuntu-latest
+    steps:
+      - uses: entireio/cli/.github/actions/sync-fork-checkpoints@main