diff --git a/.claude/hooks/delegation-guard.sh b/.claude/hooks/delegation-guard.sh
index 91d95f0..51c54eb 100755
--- a/.claude/hooks/delegation-guard.sh
+++ b/.claude/hooks/delegation-guard.sh
@@ -46,6 +46,14 @@ case "$rel_path" in
     .claude/*|.agents/*|docs/*|.github/*) hook_allow ;;
 esac
 
+# Merge conflict resolution is mechanical arbitration, not new Rust
+# implementation work. Limit the exception to the Rust file that is
+# currently unmerged so unrelated implementation files stay guarded.
+conflicted_paths="$(git -C "$HOOK_CWD" diff --name-only --diff-filter=U 2>/dev/null || true)"
+if printf '%s\n' "$conflicted_paths" | grep -qxF "$rel_path"; then
+    hook_allow
+fi
+
 if [ "$role" = "root" ] || [ -z "$role" ]; then
     hook_block "Root orchestrator should dispatch to a subagent for Rust implementation (file: $file_path). Use the 01-implementer agent."
 fi
diff --git a/.claude/hooks/tests/test_delegation_guard_subagent.sh b/.claude/hooks/tests/test_delegation_guard_subagent.sh
index 68ca4d2..e2f263e 100755
--- a/.claude/hooks/tests/test_delegation_guard_subagent.sh
+++ b/.claude/hooks/tests/test_delegation_guard_subagent.sh
@@ -118,7 +118,59 @@ for path in ".claude/hooks/role-marker.sh" ".agents/rules/foo.md" "docs/src/intr
 done
 pass "guard allows root edits of infra files (.claude/, .agents/, docs/, .github/)"
 
-# --- Step 6: Backwards-compat — if a role file exists with
+# --- Step 6: Merge conflict resolution is allowed from root. Conflict
+# marker arbitration is mechanical, so the root orchestrator may edit
+# Rust source files while the worktree has unmerged paths.
+merge_repo="$TMP_DIR/merge-repo"
+mkdir -p "$merge_repo/crates/plumb-core/src"
+git -C "$merge_repo" init -q
+git -C "$merge_repo" config user.name "Hook Test"
+git -C "$merge_repo" config user.email "hook-test@example.com"
+printf 'pub fn value() -> u8 { 1 }\n' > "$merge_repo/crates/plumb-core/src/lib.rs"
+git -C "$merge_repo" add crates/plumb-core/src/lib.rs
+git -C "$merge_repo" commit -qm "initial"
+git -C "$merge_repo" checkout -qb feature
+printf 'pub fn value() -> u8 { 2 }\n' > "$merge_repo/crates/plumb-core/src/lib.rs"
+git -C "$merge_repo" commit -am "feature" -q
+git -C "$merge_repo" checkout -q -
+printf 'pub fn value() -> u8 { 3 }\n' > "$merge_repo/crates/plumb-core/src/lib.rs"
+git -C "$merge_repo" commit -am "main" -q
+git -C "$merge_repo" merge feature >/dev/null 2>&1 && fail "expected merge conflict"
+
+merge_input="$(jq -n \
+    --arg sid "$session_id" \
+    --arg cwd "$merge_repo" \
+    --arg fp "$merge_repo/crates/plumb-core/src/lib.rs" \
+    '{session_id: $sid, cwd: $cwd, hook_event_name: "PreToolUse", tool_name: "Edit", tool_input: {file_path: $fp, content: "x"}}')"
+guard_output="$(env -u CLAUDE_SESSION_ID \
+    CLAUDE_PROJECT_DIR="$merge_repo" \
+    bash "$HOOKS_DIR/delegation-guard.sh" <<<"$merge_input")"
+decision="$(printf '%s' "$guard_output" | jq -r '.decision // empty' 2>/dev/null || true)"
+[ "$decision" = "allow" ] || fail "guard should ALLOW root .rs edit during merge conflict resolution, got: $guard_output"
+pass "guard allows root Rust edits while unmerged paths exist"
+
+unrelated_merge_input="$(jq -n \
+    --arg sid "$session_id" \
+    --arg cwd "$merge_repo" \
+    --arg fp "$merge_repo/crates/plumb-cli/src/main.rs" \
+    '{session_id: $sid, cwd: $cwd, hook_event_name: "PreToolUse", tool_name: "Edit", tool_input: {file_path: $fp, content: "x"}}')"
+guard_output="$(env -u CLAUDE_SESSION_ID \
+    CLAUDE_PROJECT_DIR="$merge_repo" \
+    bash "$HOOKS_DIR/delegation-guard.sh" <<<"$unrelated_merge_input")"
+decision="$(printf '%s' "$guard_output" | jq -r '.decision // empty' 2>/dev/null || true)"
+[ "$decision" = "block" ] || fail "guard should BLOCK unrelated root .rs edit during merge conflict resolution, got: $guard_output"
+pass "guard keeps unrelated Rust files blocked during merge conflict resolution"
+
+printf 'pub fn value() -> u8 { 2 }\n' > "$merge_repo/crates/plumb-core/src/lib.rs"
+git -C "$merge_repo" add crates/plumb-core/src/lib.rs
+guard_output="$(env -u CLAUDE_SESSION_ID \
+    CLAUDE_PROJECT_DIR="$merge_repo" \
+    bash "$HOOKS_DIR/delegation-guard.sh" <<<"$merge_input")"
+decision="$(printf '%s' "$guard_output" | jq -r '.decision // empty' 2>/dev/null || true)"
+[ "$decision" = "block" ] || fail "guard should BLOCK root .rs edit after conflict resolution, got: $guard_output"
+pass "guard blocks root Rust edits after the conflict is resolved"
+
+# --- Step 7: Backwards-compat — if a role file exists with
 # subagent:<name>, guard still allows. This preserves the existing
 # escape hatch for harnesses that DO populate agent_type at
 # SessionStart (future Claude Code versions) or for manual override.
diff --git a/.gitignore b/.gitignore
index a22304a..4ead483 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,4 +15,5 @@
 .claude/worktrees/
 .claude/memory/
 .claude/settings.local.json
+.claude-pr/
 node_modules/
diff --git a/crates/plumb-mcp/AGENTS.md b/crates/plumb-mcp/AGENTS.md
index d1ccb9d..36f2000 100644
--- a/crates/plumb-mcp/AGENTS.md
+++ b/crates/plumb-mcp/AGENTS.md
@@ -33,15 +33,13 @@ Built on `rmcp 0.2.x` with the `#[tool_router]` + `#[tool]` +
 
 ## Adding a new tool
 
-See `.agents/rules/mcp-tool-patterns.md`. Summary:
+See `.agents/rules/mcp-tool-patterns.md` for the handoff path. Summary:
 
 1. Add a `Deserialize + JsonSchema` struct for the tool's args.
 2. Add a `#[tool(description = "…")]` async method on `PlumbServer`.
 3. Add a protocol test case in `crates/plumb-cli/tests/mcp_stdio.rs`.
 4. Update `docs/src/mcp.md` tool table.
 
-Use the `09-mcp-tool-author` subagent for cookie-cutter execution.
-
 ## Depends on
 
 - `plumb-core` (types; `test-fake` feature enabled so `lint_url` can