feat(hierarchies): multi-repo single-owner ownership + structural prune (M3)

§7 of the groups/project-tool design. A group node is now authoritatively
managed by exactly one project-root; `pic apply --dir` claims, conflicts,
takes over, and (with --prune) structurally reaps owned nodes.

- Migration 0052: `projects(id, key UNIQUE)` + promote the inert
  `groups.owner_project` (0047) to a real FK (ON DELETE SET NULL) + index.
- CLI mints a stable, gitignored project key in `.picloud/project.json`
  (`pic init`, or lazily on first tree plan/apply) and presents it on every
  tree request; `pic apply --dir --takeover` flag.
- Server: prepare_tree resolves ownership read-only (plan surfaces conflicts
  + prune candidates; token folds each group's owner key). apply_tree upserts
  the project in-tx, claims created groups on insert, reconciles existing-group
  ownership under the per-node advisory lock (first-commit-wins), and prunes
  owned-but-undeclared groups leaf-first (delete=RESTRICT, never another repo's
  or a UI-owned node).
- Authz (§7.4, ownership ⟂ RBAC): takeover requires GroupAdmin per contested
  node — enforced in authz_tree (pre-tx) AND re-verified in-tx at the ownership
  decision, so --force (which waives the staleness token) can't open a
  takeover-without-admin window. The attacker-supplied project key is
  length/charset-validated server-side.
- Tests: tests/ownership.rs (claim → conflict → takeover → flip; non-admin
  takeover → 403; prune-owned-only); format_conflicts unit test; schema golden
  reblessed. tree_shape M2 journey updated to reparent in-place (a fresh dir is
  now a distinct project and would correctly conflict).

Closes the M3 milestone; reviewed (4 findings: 1 authz-bypass via --force +
key validation + 2 LOW, all fixed). M4 (trigger/route templates) remains.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/picloud-cli/tests/cli.rs

@@ -32,6 +32,7 @@ mod init;
 mod invoke;
 mod logs;
 mod output;
+mod ownership;
 mod plan;
 mod prune;
 mod pull;

crates/picloud-cli/tests/common/member.rs

@@ -78,6 +78,26 @@ pub fn grant_membership(fx: &Fixture, app_slug: &str, user_id: &str, role: &str)
     );
 }
 
+/// `POST /api/v1/admin/groups/{slug}/members` — grant `role` on a group.
+pub fn grant_group_membership(fx: &Fixture, group_slug: &str, user_id: &str, role: &str) {
+    let client = reqwest::blocking::Client::new();
+    let resp = client
+        .post(format!(
+            "{}/api/v1/admin/groups/{}/members",
+            fx.url, group_slug
+        ))
+        .bearer_auth(&fx.admin_token)
+        .json(&json!({ "user_id": user_id, "role": role }))
+        .send()
+        .expect("grant group membership");
+    assert!(
+        resp.status().is_success(),
+        "grant group membership failed: {} {}",
+        resp.status(),
+        resp.text().unwrap_or_default(),
+    );
+}
+
 /// `PATCH /api/v1/admin/apps/{slug}/members/{user_id}` — promote/demote.
 pub fn update_membership(fx: &Fixture, app_slug: &str, user_id: &str, role: &str) {
     let client = reqwest::blocking::Client::new();

crates/picloud-cli/tests/ownership.rs

@@ -0,0 +1,207 @@
+//! M3 multi-repo single-owner ownership (§7) via `pic apply --dir`:
+//!   * the first repo to apply a group CLAIMS it (its `.picloud/` project key
+//!     becomes the owner),
+//!   * a SECOND repo (different project key) applying the same group is
+//!     REJECTED with an ownership conflict,
+//!   * `--takeover` lets the second repo seize it (admin-gated; the fixture
+//!     token is instance owner), flipping ownership — proven by the first repo
+//!     now being the one rejected,
+//!   * `--prune` deletes an owned, now-undeclared, empty group; a group owned
+//!     by another repo is never touched.
+//!
+//! Each project lives in its own `TempDir`, so `pic` mints a distinct project
+//! key per repo (`.picloud/project.json`) — exactly the two-repo topology §7
+//! governs.
+
+use std::fs;
+use std::path::Path;
+
+use tempfile::TempDir;
+
+use crate::common;
+use crate::common::cleanup::GroupGuard;
+use crate::common::member;
+
+/// A single-group project dir: group `slug` under `parent`, no scripts (so a
+/// structural prune can delete it — a group holding scripts is RESTRICT-pinned).
+fn group_dir(slug: &str, parent: &str) -> TempDir {
+    let dir = TempDir::new().expect("tempdir");
+    fs::write(
+        dir.path().join("picloud.toml"),
+        format!("[group]\nslug = \"{slug}\"\nname = \"Owned Group\"\nparent = \"{parent}\"\n"),
+    )
+    .unwrap();
+    dir
+}
+
+fn apply(env: &common::TestEnv, dir: &Path, extra: &[&str]) -> std::process::Output {
+    let mut cmd = common::pic_as(env);
+    cmd.args(["apply", "--dir"]).arg(dir).args(extra);
+    cmd.output().expect("apply --dir")
+}
+
+fn ls_groups(env: &common::TestEnv) -> String {
+    String::from_utf8(
+        common::pic_as(env)
+            .args(["groups", "ls"])
+            .output()
+            .expect("groups ls")
+            .stdout,
+    )
+    .unwrap()
+}
+
+#[ignore = "needs DATABASE_URL pointing at a running Postgres"]
+#[test]
+fn first_repo_claims_second_is_rejected_then_takeover_flips_ownership() {
+    let Some(fx) = common::fixture_or_skip() else {
+        return;
+    };
+    let env = common::admin_env(fx);
+    let slug = common::unique_slug("own-g");
+    let _g = GroupGuard::new(&env.url, &env.token, &slug);
+
+    // Repo A claims the group on first apply (it does not pre-exist → created
+    // AND claimed for project A in one tx).
+    let repo_a = group_dir(&slug, "root");
+    let a1 = apply(&env, repo_a.path(), &[]);
+    assert!(
+        a1.status.success(),
+        "repo A claim apply failed: {}",
+        String::from_utf8_lossy(&a1.stderr)
+    );
+    assert!(
+        ls_groups(&env).contains(&slug),
+        "group should exist after claim"
+    );
+
+    // Repo B (a different dir → a different project key) is rejected: the group
+    // is owned by project A.
+    let repo_b = group_dir(&slug, "root");
+    let b1 = apply(&env, repo_b.path(), &[]);
+    assert!(
+        !b1.status.success(),
+        "repo B apply must be rejected (group owned by A)"
+    );
+    let b1_err = String::from_utf8_lossy(&b1.stderr).to_lowercase();
+    assert!(
+        b1_err.contains("owned by another project") || b1_err.contains("takeover"),
+        "conflict message should name the ownership clash:\n{b1_err}"
+    );
+
+    // Repo B with --takeover succeeds (the fixture token is instance owner, so
+    // it holds GroupAdmin on every node) and flips ownership to project B.
+    let b2 = apply(&env, repo_b.path(), &["--takeover"]);
+    assert!(
+        b2.status.success(),
+        "repo B --takeover should succeed: {}",
+        String::from_utf8_lossy(&b2.stderr)
+    );
+
+    // Proof the flip took: repo A — formerly the owner — is now the one
+    // rejected without --takeover.
+    let a2 = apply(&env, repo_a.path(), &[]);
+    assert!(
+        !a2.status.success(),
+        "after takeover, repo A must now be rejected (B owns the group)"
+    );
+}
+
+#[ignore = "needs DATABASE_URL pointing at a running Postgres"]
+#[test]
+fn takeover_without_group_admin_is_forbidden() {
+    // §7.4 — ownership ⟂ RBAC: `--takeover` needs GroupAdmin specifically, a
+    // second gate beyond the write caps. A non-admin member (editor) of the
+    // contested group cannot seize it for their repo.
+    let Some(fx) = common::fixture_or_skip() else {
+        return;
+    };
+    let env = common::admin_env(fx);
+    let slug = common::unique_slug("own-ta");
+    let _g = GroupGuard::new(&env.url, &env.token, &slug);
+
+    // Admin (repo A) claims the group.
+    let repo_a = group_dir(&slug, "root");
+    assert!(
+        apply(&env, repo_a.path(), &[]).status.success(),
+        "admin claim apply should succeed"
+    );
+
+    // A member with `editor` (not group_admin) on the group.
+    let m = member::member_user(fx, &common::unique_username("ta"));
+    member::grant_group_membership(fx, &slug, &m.id, "editor");
+    let member_env = common::custom_env(&fx.url, &m.token);
+    common::seed_credentials(&member_env, &m.username);
+
+    // The member's repo B (different project key) attempts a takeover → 403.
+    let repo_b = group_dir(&slug, "root");
+    let out = apply(&member_env, repo_b.path(), &["--takeover"]);
+    assert!(
+        !out.status.success(),
+        "non-admin --takeover must be forbidden"
+    );
+    let err = String::from_utf8_lossy(&out.stderr).to_lowercase();
+    assert!(
+        err.contains("forbidden") || err.contains("403"),
+        "takeover denial should be an authz error:\n{err}"
+    );
+}
+
+#[ignore = "needs DATABASE_URL pointing at a running Postgres"]
+#[test]
+fn prune_deletes_owned_undeclared_group_only() {
+    let Some(fx) = common::fixture_or_skip() else {
+        return;
+    };
+    let env = common::admin_env(fx);
+    let parent = common::unique_slug("own-par");
+    let child = common::unique_slug("own-child");
+    // Drop order: child (registered last → dropped first), then parent.
+    let _gp = GroupGuard::new(&env.url, &env.token, &parent);
+    let _gc = GroupGuard::new(&env.url, &env.token, &child);
+
+    // Repo declares parent + child (both empty); apply claims both.
+    let dir = TempDir::new().expect("tempdir");
+    fs::write(
+        dir.path().join("picloud.toml"),
+        format!("[group]\nslug = \"{parent}\"\nname = \"Parent\"\nparent = \"root\"\n"),
+    )
+    .unwrap();
+    fs::create_dir_all(dir.path().join("sub")).unwrap();
+    fs::write(
+        dir.path().join("sub/picloud.toml"),
+        format!("[group]\nslug = \"{child}\"\nname = \"Child\"\nparent = \"{parent}\"\n"),
+    )
+    .unwrap();
+    let out = apply(&env, dir.path(), &[]);
+    assert!(
+        out.status.success(),
+        "initial claim apply failed: {}",
+        String::from_utf8_lossy(&out.stderr)
+    );
+    let groups = ls_groups(&env);
+    assert!(
+        groups.contains(&parent) && groups.contains(&child),
+        "both groups should exist"
+    );
+
+    // Drop the child manifest from the SAME repo (keeping its project key) so
+    // the child becomes owned-but-undeclared, then apply --prune: the empty
+    // child is deleted; the parent (still declared) is kept.
+    fs::remove_dir_all(dir.path().join("sub")).unwrap();
+    let out2 = apply(&env, dir.path(), &["--prune", "--yes"]);
+    assert!(
+        out2.status.success(),
+        "prune apply failed: {}",
+        String::from_utf8_lossy(&out2.stderr)
+    );
+    let groups = ls_groups(&env);
+    assert!(
+        groups.contains(&parent),
+        "parent must survive prune:\n{groups}"
+    );
+    assert!(
+        !groups.contains(&child),
+        "owned, undeclared, empty child must be pruned:\n{groups}"
+    );
+}

crates/picloud-cli/tests/tree_shape.rs

@@ -83,8 +83,18 @@ fn tree_apply_creates_then_reparents_a_group() {
         "re-plan of an applied tree must be a no-op:\n{plan_txt}"
     );
 
-    // --- Reparent: move the child under the instance root. ---
-    let dir2 = group_dir(&child, "root");
+    // --- Reparent: move the child under the instance root. Rewrite the SAME
+    // repo's manifest (M3: a stable `.picloud/` project key per repo — a fresh
+    // dir would be a different project and conflict on the owned group). ---
+    fs::write(
+        dir.path().join("picloud.toml"),
+        format!(
+            "[group]\nslug = \"{child}\"\nname = \"Child Group\"\nparent = \"root\"\n\n\
+             [[scripts]]\nname = \"hello\"\nfile = \"scripts/hello.rhai\"\n"
+        ),
+    )
+    .unwrap();
+    let dir2 = &dir;
     let out = common::pic_as(&env)
         .args(["apply", "--dir"])
         .arg(dir2.path())