diff --git a/crates/manager-core/src/apply_api.rs b/crates/manager-core/src/apply_api.rs
index bfc0e41..8355ae8 100644
--- a/crates/manager-core/src/apply_api.rs
+++ b/crates/manager-core/src/apply_api.rs
@@ -183,6 +183,12 @@ async fn group_extension_points_handler(
 /// `[project]`, so the plan can preview the ownership outcome + attach ceiling.
 #[derive(Deserialize)]
 pub struct PlanRequest {
+    // Flattened so the bundle fields sit at the JSON top level: an older `pic`
+    // (pre-§7) that POSTs a bare bundle still deserializes (`project` defaults
+    // to `None`), and a newer client sends the same bundle fields plus a
+    // top-level `project` key. Keeps the plan wire compatible in both skew
+    // directions, matching the additive compatibility of the apply request.
+    #[serde(flatten)]
     pub bundle: Bundle,
     #[serde(default)]
     pub project: Option<ProjectDecl>,
@@ -327,6 +333,8 @@ struct TreeApplyRequest {
 
 #[derive(Deserialize)]
 struct TreePlanRequest {
+    // Flattened for the same bare-bundle wire compatibility as `PlanRequest`.
+    #[serde(flatten)]
     bundle: TreeBundle,
     #[serde(default)]
     project: Option<ProjectDecl>,
@@ -577,3 +585,41 @@ impl IntoResponse for ApplyError {
         (status, Json(body)).into_response()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    // §7 wire compat: the plan endpoints `#[serde(flatten)]` the bundle, so a
+    // pre-§7 client that POSTs a BARE bundle (no `{bundle: ...}` wrapper, no
+    // `project`) must still deserialize — `project` defaults to `None`.
+    #[test]
+    fn plan_request_accepts_a_bare_bundle() {
+        let bare = serde_json::json!({
+            "scripts": [],
+            "secrets": ["TOKEN"],
+        });
+        let req: PlanRequest = serde_json::from_value(bare).expect("bare bundle deserializes");
+        assert!(req.project.is_none());
+        assert_eq!(req.bundle.secrets, vec!["TOKEN".to_string()]);
+    }
+
+    // The newer wire shape — the same bundle fields at the top level plus a
+    // `project` key (what the current CLI sends) — also deserializes.
+    #[test]
+    fn plan_request_accepts_a_flattened_project() {
+        let with_proj = serde_json::json!({
+            "scripts": [],
+            "project": { "slug": "acme" },
+        });
+        let req: PlanRequest = serde_json::from_value(with_proj).expect("flattened project");
+        assert_eq!(req.project.expect("project").slug, "acme");
+    }
+
+    #[test]
+    fn tree_plan_request_accepts_a_bare_bundle() {
+        let bare = serde_json::json!({ "nodes": [] });
+        let req: TreePlanRequest = serde_json::from_value(bare).expect("bare tree bundle");
+        assert!(req.project.is_none());
+    }
+}
diff --git a/crates/picloud-cli/src/client.rs b/crates/picloud-cli/src/client.rs
index 079159b..cc53960 100644
--- a/crates/picloud-cli/src/client.rs
+++ b/crates/picloud-cli/src/client.rs
@@ -39,6 +39,25 @@ fn seg(s: &str) -> String {
     utf8_percent_encode(s, PATH_SEGMENT).to_string()
 }
 
+/// Build a `plan` request body: the bundle fields at the JSON top level plus an
+/// optional `project` key (§7). The plan endpoints `#[serde(flatten)]` the
+/// bundle, so a bare bundle (no `[project]`) is the pre-§7 wire shape — this
+/// keeps `pic plan` compatible across a CLI/server version skew in either
+/// direction (an old server ignores the extra `project`; a new server accepts
+/// the bare bundle).
+fn plan_body(
+    bundle: &serde_json::Value,
+    project: Option<&crate::manifest::ManifestProject>,
+) -> Result<serde_json::Value> {
+    let mut body = bundle.clone();
+    if let Some(p) = project {
+        if let Some(obj) = body.as_object_mut() {
+            obj.insert("project".to_string(), serde_json::to_value(p)?);
+        }
+    }
+    Ok(body)
+}
+
 pub struct Client {
     http: reqwest::Client,
     url: String,
@@ -1233,7 +1252,7 @@ impl Client {
         project: Option<&crate::manifest::ManifestProject>,
     ) -> Result<PlanDto> {
         let slug = seg(slug);
-        let body = serde_json::json!({ "bundle": bundle, "project": project });
+        let body = plan_body(bundle, project)?;
         let resp = self
             .request(
                 Method::POST,
@@ -1291,7 +1310,7 @@ impl Client {
         bundle: &serde_json::Value,
         project: Option<&crate::manifest::ManifestProject>,
     ) -> Result<TreePlanDto> {
-        let body = serde_json::json!({ "bundle": bundle, "project": project });
+        let body = plan_body(bundle, project)?;
         let resp = self
             .request(Method::POST, "/api/v1/admin/tree/plan")
             .json(&body)