diff --git a/README.md b/README.md
index b2bf34c..4ce5ed0 100644
--- a/README.md
+++ b/README.md
@@ -7,8 +7,8 @@ The MVP is Codex-first:
 - reads Codex hook JSON from stdin;
 - captures only explicit plan blocks such as `<proposed_plan>...</proposed_plan>`, `<proposed_plan title="...">...</proposed_plan>`, or `## Accepted Plan`;
 - stores captured plans and planning Q/A decisions in `.agent-plan.json`;
-- posts a new PR comment with newly captured current-branch items when an open PR exists;
-- leaves the local stack queued when no open PR exists yet.
+- posts a new PR comment with newly captured current-branch items when a valid (open, non-draft) PR exists;
+- leaves the local stack queued when no valid PR exists yet.
 
 ## CLI
 
@@ -46,7 +46,7 @@ If an agent emits known XML-style plan sections (`summary`, `flow`, `test_plan`,
 
 ## Pull Request Comments
 
-When `gh pr view` finds an open PR for the current branch, `plan-to-git` creates a new issue comment on that PR containing items that have not been posted before:
+When `gh pr view` finds an open, non-draft PR for the current branch, `plan-to-git` creates a new issue comment on that PR containing items that have not been posted before:
 
 ```markdown
 ## Agent Plan Update
@@ -54,7 +54,7 @@ When `gh pr view` finds an open PR for the current branch, `plan-to-git` creates
 ...
 ```
 
-The PR description is not edited. Closed or merged pull requests are not commented on; new items stay queued until an open PR exists. After a comment is created, `.agent-plan.json` records the posted item hashes and GitHub comment id so repeated `sync`, `hook`, or `import-codex` runs do not post the same plan again, including on a later PR.
+The PR description is not edited. Closed, merged, or still-draft pull requests are not commented on; new items stay queued until the PR is valid (open and marked ready for review). After a comment is created, `.agent-plan.json` records the posted item hashes and GitHub comment id so repeated `sync`, `hook`, or `import-codex` runs do not post the same plan again, including on a later PR.
 
 ## Safety
 
diff --git a/changelog.d/20260610_000000_guard_plan_sync_draft_prs.md b/changelog.d/20260610_000000_guard_plan_sync_draft_prs.md
new file mode 100644
index 0000000..9bd1241
--- /dev/null
+++ b/changelog.d/20260610_000000_guard_plan_sync_draft_prs.md
@@ -0,0 +1,6 @@
+---
+bump: patch
+---
+
+### Fixed
+- Kept captured plan updates queued instead of posting comments to draft pull requests, so plans stay on the upload stack until the PR is valid (open and ready for review).
diff --git a/src/github.rs b/src/github.rs
index bcda595..8e2fe9f 100644
--- a/src/github.rs
+++ b/src/github.rs
@@ -18,6 +18,9 @@ pub enum SyncStatus {
         number: u64,
         state: String,
     },
+    DraftPullRequest {
+        number: u64,
+    },
     Unchanged {
         number: u64,
     },
@@ -32,6 +35,8 @@ pub enum SyncStatus {
 struct PullRequest {
     number: u64,
     state: String,
+    #[serde(default, rename = "isDraft")]
+    is_draft: bool,
 }
 
 #[derive(Debug, Deserialize)]
@@ -53,6 +58,11 @@ pub fn sync_state(context: &GitContext, state: &mut AgentPlanState) -> AppResult
             state: pull_request.state,
         });
     }
+    if pull_request.is_draft {
+        return Ok(SyncStatus::DraftPullRequest {
+            number: pull_request.number,
+        });
+    }
 
     let (comment_body, item_ids, item_count) = {
         let items = state.unposted_items_for_pr(pull_request.number);
@@ -78,7 +88,7 @@ pub fn sync_state(context: &GitContext, state: &mut AgentPlanState) -> AppResult
 fn view_current_pr(repo_root: &Path) -> AppResult<Option<PullRequest>> {
     let output = Command::new("gh")
         .current_dir(repo_root)
-        .args(["pr", "view", "--json", "number,state,url"])
+        .args(["pr", "view", "--json", "number,state,url,isDraft"])
         .output()?;
 
     if output.status.success() {
diff --git a/src/main.rs b/src/main.rs
index dceeed7..656b2da 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -190,6 +190,9 @@ fn print_sync_status(status: &SyncStatus) {
         SyncStatus::ClosedPullRequest { number, state } => {
             println!("pull request #{number} is {state}; leaving plan items queued");
         }
+        SyncStatus::DraftPullRequest { number } => {
+            println!("pull request #{number} is a draft; leaving plan items queued");
+        }
         SyncStatus::Unchanged { number } => {
             println!("no new plan items to comment on pull request #{number}");
         }
diff --git a/tests/integration/cli.rs b/tests/integration/cli.rs
index 1e32d4a..aaed595 100644
--- a/tests/integration/cli.rs
+++ b/tests/integration/cli.rs
@@ -296,6 +296,77 @@ mod unix {
         assert!(!captured_request.exists());
     }
 
+    #[test]
+    fn hook_leaves_plans_queued_when_pr_is_draft() {
+        let temp_dir = tempfile::tempdir().expect("temp dir");
+        let bin_dir = temp_dir.path().join("bin");
+        let repo_dir = temp_dir.path().join("repo");
+        let captured_request = temp_dir.path().join("request.json");
+        fs::create_dir_all(&bin_dir).expect("bin dir");
+        fs::create_dir_all(&repo_dir).expect("repo dir");
+        write_fake_git(&bin_dir, &repo_dir);
+        write_fake_gh_draft_pr(&bin_dir, &captured_request);
+
+        run_hook(
+            &repo_dir,
+            &bin_dir,
+            &format!(
+                r#"{{
+                    "session_id":"session",
+                    "cwd":"{}",
+                    "hook_event_name":"Stop",
+                    "turn_id":"turn",
+                    "last_assistant_message":"<proposed_plan>\n# Queued\n\n- Wait for a valid PR\n</proposed_plan>"
+                }}"#,
+                repo_dir.display()
+            ),
+        );
+
+        let state = fs::read_to_string(repo_dir.join(STATE_FILE_NAME)).expect("state file");
+        assert!(state.contains("Wait for a valid PR"));
+        assert!(state.contains("\"posted_comments\": []"));
+        assert!(!captured_request.exists());
+    }
+
+    #[test]
+    fn sync_reports_draft_pr_and_does_not_comment() {
+        let temp_dir = tempfile::tempdir().expect("temp dir");
+        let bin_dir = temp_dir.path().join("bin");
+        let repo_dir = temp_dir.path().join("repo");
+        let captured_request = temp_dir.path().join("request.json");
+        fs::create_dir_all(&bin_dir).expect("bin dir");
+        fs::create_dir_all(&repo_dir).expect("repo dir");
+        write_fake_git(&bin_dir, &repo_dir);
+        write_fake_gh_draft_pr(&bin_dir, &captured_request);
+
+        run_hook(
+            &repo_dir,
+            &bin_dir,
+            &format!(
+                r#"{{
+                    "session_id":"session",
+                    "cwd":"{}",
+                    "hook_event_name":"Stop",
+                    "turn_id":"turn",
+                    "last_assistant_message":"<proposed_plan>\n# Queued\n\n- Wait for a valid PR\n</proposed_plan>"
+                }}"#,
+                repo_dir.display()
+            ),
+        );
+
+        let output = Command::new(env!("CARGO_BIN_EXE_plan-to-git"))
+            .arg("sync")
+            .current_dir(&repo_dir)
+            .env("PATH", path_with_fake_bin(&bin_dir))
+            .output()
+            .expect("run sync");
+
+        assert!(output.status.success());
+        let stdout = String::from_utf8(output.stdout).expect("stdout");
+        assert!(stdout.contains("pull request #17 is a draft; leaving plan items queued"));
+        assert!(!captured_request.exists());
+    }
+
     #[test]
     fn sync_reports_merged_pr_and_does_not_comment() {
         let temp_dir = tempfile::tempdir().expect("temp dir");
@@ -441,7 +512,7 @@ esac
     fn write_fake_gh_no_pr(bin_dir: &Path) {
         let script = r#"#!/usr/bin/env bash
 set -euo pipefail
-if [[ "$*" == "pr view --json number,state,url" ]]; then
+if [[ "$*" == "pr view --json number,state,url,isDraft" ]]; then
   echo 'no pull requests found for branch "feature/test"' >&2
   exit 1
 fi
@@ -455,7 +526,7 @@ exit 1
         let script = format!(
             r#"#!/usr/bin/env bash
 set -euo pipefail
-if [[ "$*" == "pr view --json number,state,url" ]]; then
+if [[ "$*" == "pr view --json number,state,url,isDraft" ]]; then
   printf '%s\n' '{{"number":17,"state":"OPEN","url":"https://github.com/example/repo/pull/17"}}'
   exit 0
 fi
@@ -476,7 +547,7 @@ exit 1
         let script = format!(
             r#"#!/usr/bin/env bash
 set -euo pipefail
-if [[ "$*" == "pr view --json number,state,url" ]]; then
+if [[ "$*" == "pr view --json number,state,url,isDraft" ]]; then
   printf '%s\n' '{{"number":17,"state":"{state}","url":"https://github.com/example/repo/pull/17"}}'
   exit 0
 fi
@@ -493,6 +564,27 @@ exit 1
         write_executable(&bin_dir.join("gh"), &script);
     }
 
+    fn write_fake_gh_draft_pr(bin_dir: &Path, captured_request: &Path) {
+        let script = format!(
+            r#"#!/usr/bin/env bash
+set -euo pipefail
+if [[ "$*" == "pr view --json number,state,url,isDraft" ]]; then
+  printf '%s\n' '{{"number":17,"state":"OPEN","url":"https://github.com/example/repo/pull/17","isDraft":true}}'
+  exit 0
+fi
+if [[ "$1" == "api" ]]; then
+  printf '%s\n' "$*" > "{}"
+  echo "comment API should not be called for draft PR" >&2
+  exit 1
+fi
+echo "unexpected gh args: $*" >&2
+exit 1
+"#,
+            captured_request.display()
+        );
+        write_executable(&bin_dir.join("gh"), &script);
+    }
+
     fn write_executable(path: &Path, content: &str) {
         fs::write(path, content).expect("write script");
         let mut permissions = fs::metadata(path).expect("metadata").permissions();