diff --git a/.gitignore b/.gitignore
index ff20ed00c..98b3d6d4a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,6 +31,10 @@ node_modules/
 # Git worktrees
 .worktrees/
 
+# Claude Code transient runtime locks
+.claude/scheduled_tasks.lock
+.claude/*.lock
+
 # Playwright MCP test artifacts
 tests/screenshots/current/
 tests/screenshots/diff/
diff --git a/content/guides/multi-agent/index.html b/content/guides/multi-agent/index.html
index 75cbed651..8f0b35ef9 100644
--- a/content/guides/multi-agent/index.html
+++ b/content/guides/multi-agent/index.html
@@ -1380,11 +1380,11 @@ <h1>Parallel Agents &amp; Worktrees</h1>
 <p>A <strong>git worktree</strong> solves this: it is an independent working directory backed by
 the <em>same</em> <code>.git</code> repository. Each agent gets its own files and its own checked-out
 branch, but commits, refs and history are shared. The layout is one primary
-checkout plus one sibling directory per agent:</p>
-<pre><code class="language-text">~/projects/
-├── scaffold/                  # primary checkout (you work here)
-├── scaffold-alpha/            # worktree for agent "alpha"
-└── scaffold-beta/             # worktree for agent "beta"
+checkout with all agent worktrees project-local under <code>.worktrees/</code>:</p>
+<pre><code class="language-text">scaffold/                      # primary checkout (you work here)
+└── .worktrees/                # agent worktrees (gitignored)
+    ├── alpha/                 # worktree for agent "alpha"
+    └── beta/                  # worktree for agent "beta"
 </code></pre>
 <p>So worktrees give you <strong>filesystem isolation with a shared object store</strong>:
 agents never overwrite each other's working files, but a PR merged from one
@@ -1398,20 +1398,21 @@ <h2 id="setup-setup-agent-worktreesh">Setup — <code>setup-agent-worktree.sh</c
 one parallel agent. Given a name like <code>alpha</code>, it:</p>
 <ol>
 <li><strong>Normalizes the name</strong> to a lowercase, hyphenated, alphanumeric slug (so
-<code>Agent_1</code> becomes <code>agent-1</code>), then derives the worktree directory as a
-<em>sibling</em> of the primary repo: <code>../&#x3C;repo-name>-&#x3C;slug></code>.</li>
+<code>Agent_1</code> becomes <code>agent-1</code>), then derives the worktree directory project-local
+under the primary repo: <code>.worktrees/&#x3C;slug></code>. It also ensures <code>.worktrees/</code> is
+gitignored so the worktree's checkout is never accidentally committed.</li>
 <li><strong>Creates the workspace branch</strong> <code>&#x3C;slug>-workspace</code> if it does not already
-exist <span class="fp" data-path="scripts/setup-agent-worktree.sh:40">scripts/setup-agent-worktree.sh:40</span>, then adds the worktree on
-that branch <span class="fp" data-path="scripts/setup-agent-worktree.sh:44">scripts/setup-agent-worktree.sh:44</span>. Re-running for an
+exist <span class="fp" data-path="scripts/setup-agent-worktree.sh:62">scripts/setup-agent-worktree.sh:62</span>, then adds the worktree on
+that branch <span class="fp" data-path="scripts/setup-agent-worktree.sh:65">scripts/setup-agent-worktree.sh:65</span>. Re-running for an
 existing worktree is a safe no-op.</li>
 <li><strong>Writes <code>.scaffold/identity.json</code></strong> — the stable identity that build
 observability stamps onto every event this worktree records. The script
-creates <code>.scaffold/</code> <span class="fp" data-path="scripts/setup-agent-worktree.sh:52">scripts/setup-agent-worktree.sh:52</span> and, only if no
+creates <code>.scaffold/</code> <span class="fp" data-path="scripts/setup-agent-worktree.sh:73">scripts/setup-agent-worktree.sh:73</span> and, only if no
 identity file exists yet, writes <code>worktree_id</code> (a UUID), <code>worktree_label</code>
 (the agent slug), and <code>created_at</code>
-<span class="fp" data-path="scripts/setup-agent-worktree.sh:71">scripts/setup-agent-worktree.sh:71</span>.</li>
+<span class="fp" data-path="scripts/setup-agent-worktree.sh:92">scripts/setup-agent-worktree.sh:92</span>.</li>
 <li><strong>Re-syncs Beads</strong> with a fail-soft <code>bd doctor --fix</code> when a <code>.beads/</code>
-directory is present <span class="fp" data-path="scripts/setup-agent-worktree.sh:88">scripts/setup-agent-worktree.sh:88</span>, reconciling the
+directory is present <span class="fp" data-path="scripts/setup-agent-worktree.sh:109">scripts/setup-agent-worktree.sh:109</span>, reconciling the
 worktree's Beads git hooks and project config against the installed <code>bd</code>
 version. (Beads DB sharing is automatic — worktrees discover the main repo's
 task DB via git's common directory, so there is nothing for <code>bd doctor</code> to
@@ -1467,8 +1468,8 @@ <h2 id="working-in-parallel">Working in parallel</h2>
 </ul>
 <p>Each agent otherwise follows the standard PR workflow from its own worktree:
 branch, commit, push, <code>gh pr create</code>, wait for CI, squash-merge. The shared
-object store means a merge from <code>scaffold-alpha</code> is on <code>main</code> for everyone the
-moment it lands.</p>
+object store means a merge from agent <code>alpha</code>'s worktree is on <code>main</code> for
+everyone the moment it lands.</p>
 <h2 id="teardown-harvest">Teardown &#x26; harvest</h2>
 <p>When an agent's work is merged, retire its worktree. The single command for this
 is <code>scripts/teardown-agent-worktree.sh &#x3C;worktree-path></code>, and the <strong>order of
@@ -1529,7 +1530,7 @@ <h2 id="resuming-after-a-break">Resuming after a break</h2>
 morning — does <strong>not</strong> mean re-running setup. The worktree and its
 <code>identity.json</code> persist on disk. Instead:</p>
 <ol>
-<li>Return to the agent's worktree directory (<code>../&#x3C;repo>-&#x3C;agent></code>).</li>
+<li>Return to the agent's worktree directory (<code>.worktrees/&#x3C;agent></code>).</li>
 <li>Run <strong><code>multi-agent-resume &#x3C;agent-name></code></strong> (or <code>single-agent-resume</code> for the
 non-worktree case). It verifies the worktree environment, syncs with <code>main</code>,
 reconciles task status against any PRs merged while you were away, and
diff --git a/content/guides/multi-agent/index.md b/content/guides/multi-agent/index.md
index 623813b08..b51d59b95 100644
--- a/content/guides/multi-agent/index.md
+++ b/content/guides/multi-agent/index.md
@@ -18,13 +18,13 @@ test run.
 A **git worktree** solves this: it is an independent working directory backed by
 the *same* `.git` repository. Each agent gets its own files and its own checked-out
 branch, but commits, refs and history are shared. The layout is one primary
-checkout plus one sibling directory per agent:
+checkout with all agent worktrees project-local under `.worktrees/`:
 
 ```text
-~/projects/
-├── scaffold/                  # primary checkout (you work here)
-├── scaffold-alpha/            # worktree for agent "alpha"
-└── scaffold-beta/             # worktree for agent "beta"
+scaffold/                      # primary checkout (you work here)
+└── .worktrees/                # agent worktrees (gitignored)
+    ├── alpha/                 # worktree for agent "alpha"
+    └── beta/                  # worktree for agent "beta"
 ```
 
 So worktrees give you **filesystem isolation with a shared object store**:
@@ -44,20 +44,21 @@ branch.
 one parallel agent. Given a name like `alpha`, it:
 
 1. **Normalizes the name** to a lowercase, hyphenated, alphanumeric slug (so
-   `Agent_1` becomes `agent-1`), then derives the worktree directory as a
-   *sibling* of the primary repo: `../<repo-name>-<slug>`.
+   `Agent_1` becomes `agent-1`), then derives the worktree directory project-local
+   under the primary repo: `.worktrees/<slug>`. It also ensures `.worktrees/` is
+   gitignored so the worktree's checkout is never accidentally committed.
 2. **Creates the workspace branch** `<slug>-workspace` if it does not already
-   exist :cite[scripts/setup-agent-worktree.sh:40], then adds the worktree on
-   that branch :cite[scripts/setup-agent-worktree.sh:44]. Re-running for an
+   exist :cite[scripts/setup-agent-worktree.sh:62], then adds the worktree on
+   that branch :cite[scripts/setup-agent-worktree.sh:65]. Re-running for an
    existing worktree is a safe no-op.
 3. **Writes `.scaffold/identity.json`** — the stable identity that build
    observability stamps onto every event this worktree records. The script
-   creates `.scaffold/` :cite[scripts/setup-agent-worktree.sh:52] and, only if no
+   creates `.scaffold/` :cite[scripts/setup-agent-worktree.sh:73] and, only if no
    identity file exists yet, writes `worktree_id` (a UUID), `worktree_label`
    (the agent slug), and `created_at`
-   :cite[scripts/setup-agent-worktree.sh:71].
+   :cite[scripts/setup-agent-worktree.sh:92].
 4. **Re-syncs Beads** with a fail-soft `bd doctor --fix` when a `.beads/`
-   directory is present :cite[scripts/setup-agent-worktree.sh:88], reconciling the
+   directory is present :cite[scripts/setup-agent-worktree.sh:109], reconciling the
    worktree's Beads git hooks and project config against the installed `bd`
    version. (Beads DB sharing is automatic — worktrees discover the main repo's
    task DB via git's common directory, so there is nothing for `bd doctor` to
@@ -148,8 +149,8 @@ footprint small and its branches short. The conflict-prevention rules from
 
 Each agent otherwise follows the standard PR workflow from its own worktree:
 branch, commit, push, `gh pr create`, wait for CI, squash-merge. The shared
-object store means a merge from `scaffold-alpha` is on `main` for everyone the
-moment it lands.
+object store means a merge from agent `alpha`'s worktree is on `main` for
+everyone the moment it lands.
 
 ## Teardown & harvest
 
@@ -225,7 +226,7 @@ Coming back to parallel work — a context reset, a paused session, the next
 morning — does **not** mean re-running setup. The worktree and its
 `identity.json` persist on disk. Instead:
 
-1. Return to the agent's worktree directory (`../<repo>-<agent>`).
+1. Return to the agent's worktree directory (`.worktrees/<agent>`).
 2. Run **`multi-agent-resume <agent-name>`** (or `single-agent-resume` for the
    non-worktree case). It verifies the worktree environment, syncs with `main`,
    reconciles task status against any PRs merged while you were away, and
diff --git a/content/knowledge/execution/worktree-management.md b/content/knowledge/execution/worktree-management.md
index e5bbef75e..9f3be5c58 100644
--- a/content/knowledge/execution/worktree-management.md
+++ b/content/knowledge/execution/worktree-management.md
@@ -17,7 +17,7 @@ Expert knowledge for managing git worktrees to enable parallel multi-agent execu
 
 ### Setup
 
-Use `scripts/setup-agent-worktree.sh <agent-name>` to create a worktree at `../<project>-<agent-name>/`. Each agent gets its own isolated working directory and workspace branch.
+Use `scripts/setup-agent-worktree.sh <agent-name>` to create a worktree at `.worktrees/<agent-name>/` (project-local). Each agent gets its own isolated working directory and workspace branch.
 
 ### Branching Conventions
 
@@ -40,12 +40,12 @@ After all agents finish, remove worktrees and prune stale references. Delete mer
 scripts/setup-agent-worktree.sh agent-1
 
 # This creates:
-#   ../<project>-agent-1/     (working directory)
+#   .worktrees/agent-1/        (working directory, project-local)
 #   Branch: agent-1-workspace  (workspace branch)
 ```
 
 **What the setup script does:**
-1. Creates a new worktree directory adjacent to the main repo
+1. Creates a new worktree directory project-local under `.worktrees/`
 2. Creates a workspace branch for the agent
 3. Sets up the working directory with a clean state
 4. Installs dependencies if a package manager is detected
@@ -154,7 +154,7 @@ git rebase origin/main
 
 ```bash
 # From the main repository (not from inside the worktree)
-git worktree remove ../<project>-agent-1
+git worktree remove .worktrees/agent-1
 ```
 
 **Pruning stale worktree references:**
diff --git a/content/pipeline/environment/git-workflow.md b/content/pipeline/environment/git-workflow.md
index c81275a8c..ff74e4305 100644
--- a/content/pipeline/environment/git-workflow.md
+++ b/content/pipeline/environment/git-workflow.md
@@ -26,7 +26,11 @@ parallel agents, CI pipeline, branch protection, and conflict prevention rules.
 - docs/git-workflow.md — branching strategy, commit standards, rebase strategy,
   PR workflow (8 sub-steps), task closure, agent crash recovery, branch protection,
   conflict prevention, and worktree documentation
-- scripts/setup-agent-worktree.sh — permanent worktree creation script
+- scripts/setup-agent-worktree.sh — permanent worktree creation script. Create
+  worktrees project-local at `<repo>/.worktrees/<agent-slug>` (a single,
+  consistent location — never as repo siblings like `../<repo>-<agent>`). The
+  script must ensure `.worktrees/` is gitignored before creating the worktree so
+  the worktree's checkout is never accidentally committed.
 - .github/workflows/ci.yml — CI workflow with lint and test jobs
 - .github/pull_request_template.md — PR template with task ID format
 - CLAUDE.md updated with Committing/PR Workflow, Task Closure, Parallel Sessions,
@@ -37,7 +41,9 @@ parallel agents, CI pipeline, branch protection, and conflict prevention rules.
 - (mvp) Commit format is consistent (Beads: [bd-<id>] type(scope): desc. Non-Beads: type(scope): desc)
 - (deep) PR workflow includes all 8 sub-steps (commit, AI review, rebase, push, create,
   auto-merge with --delete-branch, watch CI, confirm merge)
-- (deep) Worktree script creates permanent worktrees with workspace branches
+- (deep) Worktree script creates permanent worktrees with workspace branches at
+  the project-local path `<repo>/.worktrees/<agent-slug>` and ensures
+  `.worktrees/` is gitignored
 - (deep) If Beads: BEADS_ACTOR environment variable documented for agent identity
 - (deep) CI workflow job name matches branch protection context
 - (mvp) Branch cleanup documented for both single-agent and worktree-agent variants
diff --git a/docs/git-workflow.md b/docs/git-workflow.md
index 361b0973f..6868dcc06 100644
--- a/docs/git-workflow.md
+++ b/docs/git-workflow.md
@@ -149,13 +149,13 @@ Quality gates run both locally (`make check-all`) and in CI. The CI workflow is
 
 ## 7. Advanced: Parallel Agents (Worktrees)
 
-For parallel development, each agent gets a git worktree — an independent working directory sharing the same `.git` repository.
+For parallel development, each agent gets a git worktree — an independent working directory sharing the same `.git` repository. Worktrees live project-local under `.worktrees/` for a single, consistent location:
 
 ```
-~/projects/
-├── scaffold/                  # Main repo
-├── scaffold-agent-1/          # Worktree for agent 1
-└── scaffold-agent-2/          # Worktree for agent 2
+scaffold/                      # Main repo
+└── .worktrees/                # Agent worktrees (gitignored)
+    ├── agent-1/               # Worktree for agent 1
+    └── agent-2/               # Worktree for agent 2
 ```
 
 ### Creating Worktrees
@@ -164,7 +164,9 @@ For parallel development, each agent gets a git worktree — an independent work
 scripts/setup-agent-worktree.sh <agent-name>
 ```
 
-This creates `../<repo-name>-<agent-suffix>` with a workspace branch.
+This creates `.worktrees/<agent-suffix>` with a workspace branch. The script
+also ensures `.worktrees/` is gitignored so worktree checkouts are never
+accidentally committed.
 
 ### Worktree Workflow
 
@@ -178,6 +180,6 @@ Each agent follows the same PR workflow (section 3) from its worktree. Additiona
 
 ```bash
 git worktree list                          # List all worktrees
-git worktree remove ../scaffold-<agent>    # Remove a worktree
+git worktree remove .worktrees/<agent>     # Remove a worktree
 git worktree prune                         # Prune stale references
 ```
diff --git a/scripts/setup-agent-worktree.sh b/scripts/setup-agent-worktree.sh
index 8290b1d4a..345af7760 100755
--- a/scripts/setup-agent-worktree.sh
+++ b/scripts/setup-agent-worktree.sh
@@ -28,11 +28,32 @@ if [ -z "$agent_suffix" ]; then
 fi
 
 # ─── Resolve paths ──────────────────────────────────────────
+# Worktrees live project-local under <repo>/.worktrees/<agent> for a single,
+# consistent location (see docs/git-workflow.md §7). This matches the
+# superpowers `using-git-worktrees` convention and keeps every agent worktree
+# discoverable from one place rather than scattered as repo siblings.
 
-repo_name="$(basename "$REPO_DIR")"
-worktree_dir="$(cd "$REPO_DIR/.." && pwd)/${repo_name}-${agent_suffix}"
+worktree_dir="$REPO_DIR/.worktrees/${agent_suffix}"
 branch_name="${agent_suffix}-workspace"
 
+# ─── Ensure .worktrees/ is gitignored ───────────────────────
+# Critical: a project-local worktree dir must be ignored or its contents (a full
+# checkout) would show as untracked and could be committed. Add the rule if the
+# repo does not already ignore it.
+#
+# Use the trailing-slash path ('.worktrees/') in the check: a directory-only
+# pattern like '.worktrees/' only matches a path git knows to be a directory.
+# Without the slash, `git check-ignore` false-negatives here because this runs
+# *before* the worktree dir exists, which would append a duplicate ignore rule.
+if ! git -C "$REPO_DIR" check-ignore -q .worktrees/ 2>/dev/null; then
+    gitignore_file="$REPO_DIR/.gitignore"
+    if [ -f "$gitignore_file" ] && [ -s "$gitignore_file" ] && [ "$(tail -c1 "$gitignore_file")" != "" ]; then
+        printf '\n' >> "$gitignore_file"
+    fi
+    printf '# Git worktrees (scaffold parallel agents)\n.worktrees/\n' >> "$gitignore_file"
+    echo "Added .worktrees/ to $gitignore_file"
+fi
+
 # ─── Create worktree ────────────────────────────────────────
 
 if [ ! -d "$worktree_dir" ]; then
diff --git a/src/project/gitignore.test.ts b/src/project/gitignore.test.ts
index 266a33270..5f03f36a9 100644
--- a/src/project/gitignore.test.ts
+++ b/src/project/gitignore.test.ts
@@ -36,6 +36,7 @@ describe('ensureScaffoldGitignore', () => {
     expect(content).toContain('.scaffold/lock.json')
     expect(content).toContain('.scaffold/*.tmp')
     expect(content).toContain('.scaffold/**/*.tmp')
+    expect(content).toContain('.worktrees/')
   })
 
   it('updates existing managed block idempotently without changing user content', () => {
diff --git a/src/project/gitignore.ts b/src/project/gitignore.ts
index 96afdb0d7..2b5e4de40 100644
--- a/src/project/gitignore.ts
+++ b/src/project/gitignore.ts
@@ -11,6 +11,10 @@ const MANAGED_LINES = [
   '.scaffold/lock.json',
   '.scaffold/*.tmp',
   '.scaffold/**/*.tmp',
+  // Parallel-agent worktrees live at <repo>/.worktrees/<agent>; ignore so a
+  // worktree's full checkout is never accidentally committed (see
+  // scripts/setup-agent-worktree.sh and docs/git-workflow.md §7).
+  '.worktrees/',
 ]
 
 const DANGEROUS_RULES = new Set([
diff --git a/tests/setup-agent-worktree.bats b/tests/setup-agent-worktree.bats
index 042660f60..fe3c06133 100644
--- a/tests/setup-agent-worktree.bats
+++ b/tests/setup-agent-worktree.bats
@@ -29,9 +29,9 @@ setup() {
 }
 
 teardown() {
+    # Worktrees now live inside the repo at <repo>/.worktrees/, so removing
+    # CLONE_DIR (including its .git and worktree metadata) also removes them.
     rm -rf "$ORIG_DIR" "$CLONE_DIR"
-    # Clean up any worktrees that were created
-    rm -rf "$RESOLVED_TMPDIR"/scaffold-$$-*
 }
 
 @test "exits 1 with usage message when no arguments provided" {
@@ -40,10 +40,34 @@ teardown() {
     [[ "$output" == *"Usage:"* ]]
 }
 
-@test "creates worktree at expected path" {
+@test "creates worktree under <repo>/.worktrees/<name>" {
     run "$CLONE_DIR/scripts/setup-agent-worktree.sh" "agent-alpha"
     [ "$status" -eq 0 ]
-    [ -d "$RESOLVED_TMPDIR/scaffold-$$-agent-alpha" ]
+    [ -d "$CLONE_DIR/.worktrees/agent-alpha" ]
+}
+
+@test "does not create a sibling worktree directory" {
+    run "$CLONE_DIR/scripts/setup-agent-worktree.sh" "agent-alpha"
+    [ "$status" -eq 0 ]
+    [ ! -d "$RESOLVED_TMPDIR/scaffold-$$-agent-alpha" ]
+}
+
+@test "ensures .worktrees/ is gitignored" {
+    run "$CLONE_DIR/scripts/setup-agent-worktree.sh" "agent-alpha"
+    [ "$status" -eq 0 ]
+    run git -C "$CLONE_DIR" check-ignore -q .worktrees/
+    [ "$status" -eq 0 ]
+}
+
+@test "does not duplicate .worktrees/ when it is already gitignored" {
+    # .worktrees/ already ignored, but the directory does not exist yet — the
+    # check must use the trailing-slash form or it false-negatives and appends
+    # a duplicate rule. Regression guard for that.
+    printf '.worktrees/\n' > "$CLONE_DIR/.gitignore"
+    run "$CLONE_DIR/scripts/setup-agent-worktree.sh" "agent-echo"
+    [ "$status" -eq 0 ]
+    run grep -c '^\.worktrees/$' "$CLONE_DIR/.gitignore"
+    [ "$output" = "1" ]
 }
 
 @test "idempotent: succeeds if worktree already exists" {
@@ -60,14 +84,14 @@ teardown() {
 @test "normalizes agent name to lowercase with hyphens" {
     run "$CLONE_DIR/scripts/setup-agent-worktree.sh" "Agent_Charlie"
     [ "$status" -eq 0 ]
-    [ -d "$RESOLVED_TMPDIR/scaffold-$$-agent-charlie" ]
+    [ -d "$CLONE_DIR/.worktrees/agent-charlie" ]
 }
 
 @test "creates workspace branch for the agent" {
     run "$CLONE_DIR/scripts/setup-agent-worktree.sh" "agent-delta"
     [ "$status" -eq 0 ]
     # Check that the branch exists in the worktree
-    local worktree_dir="$RESOLVED_TMPDIR/scaffold-$$-agent-delta"
+    local worktree_dir="$CLONE_DIR/.worktrees/agent-delta"
     run git -C "$worktree_dir" branch --show-current
     [ "$output" = "agent-delta-workspace" ]
 }