diff --git a/.claude/commands/review-pr.md b/.claude/commands/review-pr.md
index 02a4a66..9c9098f 100644
--- a/.claude/commands/review-pr.md
+++ b/.claude/commands/review-pr.md
@@ -12,18 +12,43 @@ Pull request(s): $ARGUMENTS
 1. **Retrieve PR Details**
    - Use the GH CLI tool to retrieve the details (descriptions, diffs, comments, feedback, reviews, etc)
 
-2. **Analyze Codebase Impact**
-   - Use 3 deepdive subagents to analyze the impact on the codebase
+2. **Assess PR Complexity**
 
-3. **Vision Alignment Check**
+   After retrieving PR details, assess complexity based on:
+   - Number of files changed
+   - Lines added/removed
+   - Number of contributors/commits
+   - Whether changes touch core/architectural files
+
+   ### Complexity Tiers
+
+   **Simple** (no deep dive agents needed):
+   - ≤5 files changed AND ≤100 lines changed AND single author
+   - Review directly without spawning agents
+
+   **Medium** (1-2 deep dive agents):
+   - 6-15 files changed, OR 100-500 lines, OR 2 contributors
+   - Spawn 1 agent for focused areas, 2 if changes span multiple domains
+
+   **Complex** (up to 3 deep dive agents):
+   - >15 files, OR >500 lines, OR >2 contributors, OR touches core architecture
+   - Spawn up to 3 agents to analyze different aspects (e.g., security, performance, architecture)
+
+3. **Analyze Codebase Impact**
+   - Based on the complexity tier determined above, spawn the appropriate number of deep dive subagents
+   - For Simple PRs: analyze directly without spawning agents
+   - For Medium PRs: spawn 1-2 agents focusing on the most impacted areas
+   - For Complex PRs: spawn up to 3 agents to cover security, performance, and architectural concerns
+
+4. **Vision Alignment Check**
    - Read the project's README.md and CLAUDE.md to understand the application's core purpose
    - Assess whether this PR aligns with the application's intended functionality
    - If the changes deviate significantly from the core vision or add functionality that doesn't serve the application's purpose, note this in the review
    - This is not a blocker, but should be flagged for the reviewer's consideration
 
-4. **Safety Assessment**
+5. **Safety Assessment**
    - Provide a review on whether the PR is safe to merge as-is
    - Provide any feedback in terms of risk level
 
-5. **Improvements**
+6. **Improvements**
    - Propose any improvements in terms of importance and complexity
\ No newline at end of file
diff --git a/registry.py b/registry.py
index 20d31df..f84803e 100644
--- a/registry.py
+++ b/registry.py
@@ -16,7 +16,7 @@ from datetime import datetime
 from pathlib import Path
 from typing import Any
 
-from sqlalchemy import Column, DateTime, String, create_engine
+from sqlalchemy import Column, DateTime, Integer, String, create_engine, text
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker
 
@@ -85,6 +85,7 @@ class Project(Base):
     name = Column(String(50), primary_key=True, index=True)
     path = Column(String, nullable=False)  # POSIX format for cross-platform
     created_at = Column(DateTime, nullable=False)
+    default_concurrency = Column(Integer, nullable=False, default=3)
 
 
 class Settings(Base):
@@ -146,12 +147,26 @@ def _get_engine():
                     }
                 )
                 Base.metadata.create_all(bind=_engine)
+                _migrate_add_default_concurrency(_engine)
                 _SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=_engine)
                 logger.debug("Initialized registry database at: %s", db_path)
 
     return _engine, _SessionLocal
 
 
+def _migrate_add_default_concurrency(engine) -> None:
+    """Add default_concurrency column if missing (for existing databases)."""
+    with engine.connect() as conn:
+        result = conn.execute(text("PRAGMA table_info(projects)"))
+        columns = [row[1] for row in result.fetchall()]
+        if "default_concurrency" not in columns:
+            conn.execute(text(
+                "ALTER TABLE projects ADD COLUMN default_concurrency INTEGER DEFAULT 3"
+            ))
+            conn.commit()
+            logger.info("Migrated projects table: added default_concurrency column")
+
+
 @contextmanager
 def _get_session():
     """
@@ -307,7 +322,8 @@ def list_registered_projects() -> dict[str, dict[str, Any]]:
         return {
             p.name: {
                 "path": p.path,
-                "created_at": p.created_at.isoformat() if p.created_at else None
+                "created_at": p.created_at.isoformat() if p.created_at else None,
+                "default_concurrency": getattr(p, 'default_concurrency', 3) or 3
             }
             for p in projects
         }
@@ -333,7 +349,8 @@ def get_project_info(name: str) -> dict[str, Any] | None:
             return None
         return {
             "path": project.path,
-            "created_at": project.created_at.isoformat() if project.created_at else None
+            "created_at": project.created_at.isoformat() if project.created_at else None,
+            "default_concurrency": getattr(project, 'default_concurrency', 3) or 3
         }
     finally:
         session.close()
@@ -362,6 +379,55 @@ def update_project_path(name: str, new_path: Path) -> bool:
     return True
 
 
+def get_project_concurrency(name: str) -> int:
+    """
+    Get project's default concurrency (1-5).
+
+    Args:
+        name: The project name.
+
+    Returns:
+        The default concurrency value (defaults to 3 if not set or project not found).
+    """
+    _, SessionLocal = _get_engine()
+    session = SessionLocal()
+    try:
+        project = session.query(Project).filter(Project.name == name).first()
+        if project is None:
+            return 3
+        return getattr(project, 'default_concurrency', 3) or 3
+    finally:
+        session.close()
+
+
+def set_project_concurrency(name: str, concurrency: int) -> bool:
+    """
+    Set project's default concurrency (1-5).
+
+    Args:
+        name: The project name.
+        concurrency: The concurrency value (1-5).
+
+    Returns:
+        True if updated, False if project wasn't found.
+
+    Raises:
+        ValueError: If concurrency is not between 1 and 5.
+    """
+    if concurrency < 1 or concurrency > 5:
+        raise ValueError("concurrency must be between 1 and 5")
+
+    with _get_session() as session:
+        project = session.query(Project).filter(Project.name == name).first()
+        if not project:
+            return False
+
+        project.default_concurrency = concurrency
+
+    logger.info("Set project '%s' default_concurrency to %d", name, concurrency)
+    return True
+
+
 # =============================================================================
 # Validation Functions
 # =============================================================================
diff --git a/server/routers/projects.py b/server/routers/projects.py
index 68cf526..70e27cc 100644
--- a/server/routers/projects.py
+++ b/server/routers/projects.py
@@ -18,6 +18,7 @@ from ..schemas import (
     ProjectDetail,
     ProjectPrompts,
     ProjectPromptsUpdate,
+    ProjectSettingsUpdate,
     ProjectStats,
     ProjectSummary,
 )
@@ -63,13 +64,23 @@ def _get_registry_functions():
         sys.path.insert(0, str(root))
 
     from registry import (
+        get_project_concurrency,
         get_project_path,
         list_registered_projects,
         register_project,
+        set_project_concurrency,
         unregister_project,
         validate_project_path,
     )
-    return register_project, unregister_project, get_project_path, list_registered_projects, validate_project_path
+    return (
+        register_project,
+        unregister_project,
+        get_project_path,
+        list_registered_projects,
+        validate_project_path,
+        get_project_concurrency,
+        set_project_concurrency,
+    )
 
 
 router = APIRouter(prefix="/api/projects", tags=["projects"])
@@ -102,7 +113,8 @@ def get_project_stats(project_dir: Path) -> ProjectStats:
 async def list_projects():
     """List all registered projects."""
     _init_imports()
-    _, _, _, list_registered_projects, validate_project_path = _get_registry_functions()
+    (_, _, _, list_registered_projects, validate_project_path,
+     get_project_concurrency, _) = _get_registry_functions()
 
     projects = list_registered_projects()
     result = []
@@ -123,6 +135,7 @@ async def list_projects():
             path=info["path"],
             has_spec=has_spec,
             stats=stats,
+            default_concurrency=info.get("default_concurrency", 3),
         ))
 
     return result
@@ -132,7 +145,8 @@ async def list_projects():
 async def create_project(project: ProjectCreate):
     """Create a new project at the specified path."""
     _init_imports()
-    register_project, _, get_project_path, list_registered_projects, _ = _get_registry_functions()
+    (register_project, _, get_project_path, list_registered_projects,
+     _, _, _) = _get_registry_functions()
 
     name = validate_project_name(project.name)
     project_path = Path(project.path).resolve()
@@ -203,6 +217,7 @@ async def create_project(project: ProjectCreate):
         path=project_path.as_posix(),
         has_spec=False,  # Just created, no spec yet
         stats=ProjectStats(passing=0, total=0, percentage=0.0),
+        default_concurrency=3,
     )
 
 
@@ -210,7 +225,7 @@ async def create_project(project: ProjectCreate):
 async def get_project(name: str):
     """Get detailed information about a project."""
     _init_imports()
-    _, _, get_project_path, _, _ = _get_registry_functions()
+    (_, _, get_project_path, _, _, get_project_concurrency, _) = _get_registry_functions()
 
     name = validate_project_name(name)
     project_dir = get_project_path(name)
@@ -231,6 +246,7 @@ async def get_project(name: str):
         has_spec=has_spec,
         stats=stats,
         prompts_dir=str(prompts_dir),
+        default_concurrency=get_project_concurrency(name),
     )
 
 
@@ -244,7 +260,7 @@ async def delete_project(name: str, delete_files: bool = False):
         delete_files: If True, also delete the project directory and files
     """
     _init_imports()
-    _, unregister_project, get_project_path, _, _ = _get_registry_functions()
+    (_, unregister_project, get_project_path, _, _, _, _) = _get_registry_functions()
 
     name = validate_project_name(name)
     project_dir = get_project_path(name)
@@ -280,7 +296,7 @@ async def delete_project(name: str, delete_files: bool = False):
 async def get_project_prompts(name: str):
     """Get the content of project prompt files."""
     _init_imports()
-    _, _, get_project_path, _, _ = _get_registry_functions()
+    (_, _, get_project_path, _, _, _, _) = _get_registry_functions()
 
     name = validate_project_name(name)
     project_dir = get_project_path(name)
@@ -313,7 +329,7 @@ async def get_project_prompts(name: str):
 async def update_project_prompts(name: str, prompts: ProjectPromptsUpdate):
     """Update project prompt files."""
     _init_imports()
-    _, _, get_project_path, _, _ = _get_registry_functions()
+    (_, _, get_project_path, _, _, _, _) = _get_registry_functions()
 
     name = validate_project_name(name)
     project_dir = get_project_path(name)
@@ -343,7 +359,7 @@ async def update_project_prompts(name: str, prompts: ProjectPromptsUpdate):
 async def get_project_stats_endpoint(name: str):
     """Get current progress statistics for a project."""
     _init_imports()
-    _, _, get_project_path, _, _ = _get_registry_functions()
+    (_, _, get_project_path, _, _, _, _) = _get_registry_functions()
 
     name = validate_project_name(name)
     project_dir = get_project_path(name)
@@ -355,3 +371,40 @@ async def get_project_stats_endpoint(name: str):
         raise HTTPException(status_code=404, detail="Project directory not found")
 
     return get_project_stats(project_dir)
+
+
+@router.patch("/{name}/settings", response_model=ProjectDetail)
+async def update_project_settings(name: str, settings: ProjectSettingsUpdate):
+    """Update project-level settings (concurrency, etc.)."""
+    _init_imports()
+    (_, _, get_project_path, _, _, get_project_concurrency,
+     set_project_concurrency) = _get_registry_functions()
+
+    name = validate_project_name(name)
+    project_dir = get_project_path(name)
+
+    if not project_dir:
+        raise HTTPException(status_code=404, detail=f"Project '{name}' not found")
+
+    if not project_dir.exists():
+        raise HTTPException(status_code=404, detail="Project directory not found")
+
+    # Update concurrency if provided
+    if settings.default_concurrency is not None:
+        success = set_project_concurrency(name, settings.default_concurrency)
+        if not success:
+            raise HTTPException(status_code=500, detail="Failed to update concurrency")
+
+    # Return updated project details
+    has_spec = _check_spec_exists(project_dir)
+    stats = get_project_stats(project_dir)
+    prompts_dir = _get_project_prompts_dir(project_dir)
+
+    return ProjectDetail(
+        name=name,
+        path=project_dir.as_posix(),
+        has_spec=has_spec,
+        stats=stats,
+        prompts_dir=str(prompts_dir),
+        default_concurrency=get_project_concurrency(name),
+    )
diff --git a/server/schemas.py b/server/schemas.py
index 0a2807c..03e73ef 100644
--- a/server/schemas.py
+++ b/server/schemas.py
@@ -45,6 +45,7 @@ class ProjectSummary(BaseModel):
     path: str
     has_spec: bool
     stats: ProjectStats
+    default_concurrency: int = 3
 
 
 class ProjectDetail(BaseModel):
@@ -54,6 +55,7 @@ class ProjectDetail(BaseModel):
     has_spec: bool
     stats: ProjectStats
     prompts_dir: str
+    default_concurrency: int = 3
 
 
 class ProjectPrompts(BaseModel):
@@ -70,6 +72,18 @@ class ProjectPromptsUpdate(BaseModel):
     coding_prompt: str | None = None
 
 
+class ProjectSettingsUpdate(BaseModel):
+    """Request schema for updating project-level settings."""
+    default_concurrency: int | None = None
+
+    @field_validator('default_concurrency')
+    @classmethod
+    def validate_concurrency(cls, v: int | None) -> int | None:
+        if v is not None and (v < 1 or v > 5):
+            raise ValueError("default_concurrency must be between 1 and 5")
+        return v
+
+
 # ============================================================================
 # Feature Schemas
 # ============================================================================
diff --git a/ui/src/App.tsx b/ui/src/App.tsx
index ddde90f..476539c 100644
--- a/ui/src/App.tsx
+++ b/ui/src/App.tsx
@@ -268,6 +268,7 @@ function App() {
                   <AgentControl
                     projectName={selectedProject}
                     status={wsState.agentStatus}
+                    defaultConcurrency={selectedProjectData?.default_concurrency}
                   />
 
                   <DevServerControl
diff --git a/ui/src/components/AgentControl.tsx b/ui/src/components/AgentControl.tsx
index c08a1bd..cc6e3ba 100644
--- a/ui/src/components/AgentControl.tsx
+++ b/ui/src/components/AgentControl.tsx
@@ -1,9 +1,10 @@
-import { useState } from 'react'
+import { useState, useEffect, useRef, useCallback } from 'react'
 import { Play, Square, Loader2, GitBranch, Clock } from 'lucide-react'
 import {
   useStartAgent,
   useStopAgent,
   useSettings,
+  useUpdateProjectSettings,
 } from '../hooks/useProjects'
 import { useNextScheduledRun } from '../hooks/useSchedules'
 import { formatNextRun, formatEndTime } from '../lib/timeUtils'
@@ -15,14 +16,47 @@ import { Badge } from '@/components/ui/badge'
 interface AgentControlProps {
   projectName: string
   status: AgentStatus
+  defaultConcurrency?: number
 }
 
-export function AgentControl({ projectName, status }: AgentControlProps) {
+export function AgentControl({ projectName, status, defaultConcurrency = 3 }: AgentControlProps) {
   const { data: settings } = useSettings()
   const yoloMode = settings?.yolo_mode ?? false
 
   // Concurrency: 1 = single agent, 2-5 = parallel
-  const [concurrency, setConcurrency] = useState(3)
+  const [concurrency, setConcurrency] = useState(defaultConcurrency)
+
+  // Sync concurrency when project changes or defaultConcurrency updates
+  useEffect(() => {
+    setConcurrency(defaultConcurrency)
+  }, [defaultConcurrency])
+
+  // Debounced save for concurrency changes
+  const updateProjectSettings = useUpdateProjectSettings(projectName)
+  const saveTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+
+  const handleConcurrencyChange = useCallback((newConcurrency: number) => {
+    setConcurrency(newConcurrency)
+
+    // Clear previous timeout
+    if (saveTimeoutRef.current) {
+      clearTimeout(saveTimeoutRef.current)
+    }
+
+    // Debounce save (500ms)
+    saveTimeoutRef.current = setTimeout(() => {
+      updateProjectSettings.mutate({ default_concurrency: newConcurrency })
+    }, 500)
+  }, [updateProjectSettings])
+
+  // Cleanup timeout on unmount
+  useEffect(() => {
+    return () => {
+      if (saveTimeoutRef.current) {
+        clearTimeout(saveTimeoutRef.current)
+      }
+    }
+  }, [])
 
   const startAgent = useStartAgent(projectName)
   const stopAgent = useStopAgent(projectName)
@@ -57,7 +91,7 @@ export function AgentControl({ projectName, status }: AgentControlProps) {
               min={1}
               max={5}
               value={concurrency}
-              onChange={(e) => setConcurrency(Number(e.target.value))}
+              onChange={(e) => handleConcurrencyChange(Number(e.target.value))}
               disabled={isLoading}
               className="w-16 h-2 accent-primary cursor-pointer"
               title={`${concurrency} concurrent agent${concurrency > 1 ? 's' : ''}`}
diff --git a/ui/src/hooks/useProjects.ts b/ui/src/hooks/useProjects.ts
index 0af7763..4ed3914 100644
--- a/ui/src/hooks/useProjects.ts
+++ b/ui/src/hooks/useProjects.ts
@@ -4,7 +4,7 @@
 
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
 import * as api from '../lib/api'
-import type { FeatureCreate, FeatureUpdate, ModelsResponse, Settings, SettingsUpdate } from '../lib/types'
+import type { FeatureCreate, FeatureUpdate, ModelsResponse, ProjectSettingsUpdate, Settings, SettingsUpdate } from '../lib/types'
 
 // ============================================================================
 // Projects
@@ -48,6 +48,19 @@ export function useDeleteProject() {
   })
 }
 
+export function useUpdateProjectSettings(projectName: string) {
+  const queryClient = useQueryClient()
+
+  return useMutation({
+    mutationFn: (settings: ProjectSettingsUpdate) =>
+      api.updateProjectSettings(projectName, settings),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['projects'] })
+      queryClient.invalidateQueries({ queryKey: ['project', projectName] })
+    },
+  })
+}
+
 // ============================================================================
 // Features
 // ============================================================================
diff --git a/ui/src/lib/api.ts b/ui/src/lib/api.ts
index 7ef9a8a..ce3354e 100644
--- a/ui/src/lib/api.ts
+++ b/ui/src/lib/api.ts
@@ -6,6 +6,7 @@ import type {
   ProjectSummary,
   ProjectDetail,
   ProjectPrompts,
+  ProjectSettingsUpdate,
   FeatureListResponse,
   Feature,
   FeatureCreate,
@@ -100,6 +101,16 @@ export async function updateProjectPrompts(
   })
 }
 
+export async function updateProjectSettings(
+  name: string,
+  settings: ProjectSettingsUpdate
+): Promise<ProjectDetail> {
+  return fetchJSON(`/projects/${encodeURIComponent(name)}/settings`, {
+    method: 'PATCH',
+    body: JSON.stringify(settings),
+  })
+}
+
 // ============================================================================
 // Features API
 // ============================================================================
diff --git a/ui/src/lib/types.ts b/ui/src/lib/types.ts
index d883432..269c2ef 100644
--- a/ui/src/lib/types.ts
+++ b/ui/src/lib/types.ts
@@ -15,6 +15,7 @@ export interface ProjectSummary {
   path: string
   has_spec: boolean
   stats: ProjectStats
+  default_concurrency: number
 }
 
 export interface ProjectDetail extends ProjectSummary {
@@ -536,6 +537,10 @@ export interface SettingsUpdate {
   testing_agent_ratio?: number
 }
 
+export interface ProjectSettingsUpdate {
+  default_concurrency?: number
+}
+
 // ============================================================================
 // Schedule Types
 // ============================================================================