diff --git a/packages/squad-sdk/package.json b/packages/squad-sdk/package.json
index 5fc8902e3..87f8b5318 100644
--- a/packages/squad-sdk/package.json
+++ b/packages/squad-sdk/package.json
@@ -30,6 +30,10 @@
       "types": "./dist/agents/index.d.ts",
       "import": "./dist/agents/index.js"
     },
+    "./agents/personal": {
+      "types": "./dist/agents/personal.d.ts",
+      "import": "./dist/agents/personal.js"
+    },
     "./adapter": {
       "types": "./dist/adapter/types.d.ts",
       "import": "./dist/adapter/types.js"
diff --git a/packages/squad-sdk/src/agents/index.ts b/packages/squad-sdk/src/agents/index.ts
index e6f8f3e5f..ff14e4e09 100644
--- a/packages/squad-sdk/src/agents/index.ts
+++ b/packages/squad-sdk/src/agents/index.ts
@@ -71,6 +71,14 @@ export {
   type OnboardResult,
 } from './onboarding.js';
 
+// --- Personal Squad Agents ---
+export {
+  resolvePersonalAgents,
+  mergeSessionCast,
+  type PersonalAgentMeta,
+  type PersonalAgentManifest,
+} from './personal.js';
+
 // --- Charter Types ---
 
 export interface AgentCharter {
diff --git a/packages/squad-sdk/src/agents/personal.ts b/packages/squad-sdk/src/agents/personal.ts
new file mode 100644
index 000000000..e200f4974
--- /dev/null
+++ b/packages/squad-sdk/src/agents/personal.ts
@@ -0,0 +1,96 @@
+/**
+ * Personal Squad Agent Resolution
+ * 
+ * Discovers and merges personal agents from the user's personal squad directory
+ * into project session casts. Personal agents are ambient — they're automatically
+ * available in all project contexts with ghost protocol enforced.
+ * 
+ * @module agents/personal
+ */
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { resolvePersonalSquadDir } from '../resolution.js';
+import { AgentManifest } from '../config/agent-source.js';
+
+/** Metadata tag for personal agents in a session cast */
+export interface PersonalAgentMeta {
+  /** Always 'personal' for personal squad agents */
+  origin: 'personal';
+  /** Absolute path to the personal agent's directory */
+  sourceDir: string;
+  /** Whether ghost protocol is enforced (always true in project context) */
+  ghostProtocol: boolean;
+}
+
+/** A project agent manifest augmented with personal origin info */
+export type PersonalAgentManifest = AgentManifest & {
+  personal: PersonalAgentMeta;
+};
+
+/**
+ * Discover personal agents from the user's personal squad directory.
+ * Returns empty array if personal squad is disabled or doesn't exist.
+ */
+export async function resolvePersonalAgents(): Promise<PersonalAgentManifest[]> {
+  const personalDir = resolvePersonalSquadDir();
+  if (!personalDir) return [];
+  
+  const agentsDir = path.join(personalDir, 'agents');
+  if (!fs.existsSync(agentsDir)) return [];
+  
+  const entries = await fs.promises.readdir(agentsDir, { withFileTypes: true });
+  const agents: PersonalAgentManifest[] = [];
+  
+  for (const entry of entries) {
+    if (!entry.isDirectory()) continue;
+    
+    const charterPath = path.join(agentsDir, entry.name, 'charter.md');
+    if (!fs.existsSync(charterPath)) continue;
+    
+    const charterContent = await fs.promises.readFile(charterPath, 'utf-8');
+    const meta = parseCharterMetadataBasic(charterContent);
+    
+    agents.push({
+      name: entry.name,
+      role: meta.role || 'personal',
+      source: 'personal',
+      personal: {
+        origin: 'personal',
+        sourceDir: path.join(agentsDir, entry.name),
+        ghostProtocol: true,
+      },
+    });
+  }
+  
+  return agents;
+}
+
+/** Basic charter metadata parser for personal agents */
+function parseCharterMetadataBasic(content: string): { role?: string; name?: string } {
+  const roleMatch = content.match(/\*\*Role:\*\*\s*(.+)/);
+  const nameMatch = content.match(/\*\*Name:\*\*\s*(.+)/);
+  return {
+    role: roleMatch?.[1]?.trim(),
+    name: nameMatch?.[1]?.trim(),
+  };
+}
+
+/**
+ * Merge personal agents into a project session cast.
+ * Personal agents are tagged with origin: 'personal' and ghost protocol is enforced.
+ * Duplicate names: project agents take precedence over personal agents.
+ */
+export function mergeSessionCast(
+  projectAgents: AgentManifest[],
+  personalAgents: PersonalAgentManifest[]
+): (AgentManifest | PersonalAgentManifest)[] {
+  const projectNames = new Set(projectAgents.map(a => a.name.toLowerCase()));
+  
+  // Filter out personal agents that conflict with project agent names
+  const uniquePersonal = personalAgents.filter(
+    a => !projectNames.has(a.name.toLowerCase())
+  );
+  
+  return [...projectAgents, ...uniquePersonal];
+}
diff --git a/packages/squad-sdk/src/index.ts b/packages/squad-sdk/src/index.ts
index 903c56885..dfac014fb 100644
--- a/packages/squad-sdk/src/index.ts
+++ b/packages/squad-sdk/src/index.ts
@@ -10,10 +10,12 @@ const pkg = require('../package.json');
 export const VERSION: string = pkg.version;
 
 // Export public API
-export { resolveSquad, resolveGlobalSquadPath, ensureSquadPath, loadDirConfig, isConsultMode } from './resolution.js';
+export { resolveSquad, resolveGlobalSquadPath, resolvePersonalSquadDir, ensureSquadPath, ensureSquadPathTriple, loadDirConfig, isConsultMode } from './resolution.js';
 export type { SquadDirConfig, ResolvedSquadPaths } from './resolution.js';
 export * from './config/index.js';
 export * from './agents/onboarding.js';
+export { resolvePersonalAgents, mergeSessionCast } from './agents/personal.js';
+export type { PersonalAgentMeta, PersonalAgentManifest } from './agents/personal.js';
 export * from './casting/index.js';
 export * from './skills/index.js';
 export { selectResponseTier, getTier } from './coordinator/response-tiers.js';
diff --git a/packages/squad-sdk/src/resolution.ts b/packages/squad-sdk/src/resolution.ts
index cbc3acefe..fe45a8bfd 100644
--- a/packages/squad-sdk/src/resolution.ts
+++ b/packages/squad-sdk/src/resolution.ts
@@ -47,6 +47,8 @@ export interface ResolvedSquadPaths {
   projectDir: string;
   /** Team identity root (agents, casting, skills) */
   teamDir: string;
+  /** User's personal squad dir, null if not found or disabled */
+  personalDir: string | null;
   config: SquadDirConfig | null;
   name: '.squad' | '.ai-team';
   isLegacy: boolean;
@@ -199,6 +201,7 @@ export function resolveSquadPaths(startDir?: string): ResolvedSquadPaths | null
       mode: 'remote',
       projectDir,
       teamDir,
+      personalDir: resolvePersonalSquadDir(),
       config,
       name,
       isLegacy,
@@ -210,6 +213,7 @@ export function resolveSquadPaths(startDir?: string): ResolvedSquadPaths | null
     mode: 'local',
     projectDir,
     teamDir: projectDir,
+    personalDir: resolvePersonalSquadDir(),
     config,
     name,
     isLegacy,
@@ -254,6 +258,25 @@ export function resolveGlobalSquadPath(): string {
   return globalDir;
 }
 
+/**
+ * Resolves the user's personal squad directory.
+ * Returns null if SQUAD_NO_PERSONAL is set or directory doesn't exist.
+ * 
+ * Platform paths:
+ * - Windows: %APPDATA%/squad/personal-squad
+ * - macOS: ~/Library/Application Support/squad/personal-squad
+ * - Linux: $XDG_CONFIG_HOME/squad/personal-squad or ~/.config/squad/personal-squad
+ */
+export function resolvePersonalSquadDir(): string | null {
+  if (process.env['SQUAD_NO_PERSONAL']) return null;
+  
+  const globalDir = resolveGlobalSquadPath();
+  const personalDir = path.join(globalDir, 'personal-squad');
+  
+  if (!fs.existsSync(personalDir)) return null;
+  return personalDir;
+}
+
 /**
  * Validate that a file path is within `.squad/` or the system temp directory.
  *
@@ -323,6 +346,33 @@ export function ensureSquadPathDual(filePath: string, projectDir: string, teamDi
   );
 }
 
+/**
+ * Validates a file path is inside one of three allowed directories:
+ * projectDir, teamDir, personalDir, or system temp.
+ * Extends ensureSquadPathDual() for triple-root (project + team + personal).
+ */
+export function ensureSquadPathTriple(
+  filePath: string,
+  projectDir: string,
+  teamDir: string,
+  personalDir: string | null
+): string {
+  const resolved = path.resolve(filePath);
+  const tmpDir = os.tmpdir();
+  
+  const allowed = [projectDir, teamDir, personalDir, tmpDir].filter(Boolean) as string[];
+  
+  for (const dir of allowed) {
+    if (resolved.startsWith(path.resolve(dir) + path.sep) || resolved === path.resolve(dir)) {
+      return resolved;
+    }
+  }
+  
+  throw new Error(
+    `Path "${resolved}" is outside all allowed directories: ${allowed.join(', ')}`
+  );
+}
+
 /**
  * ensureSquadPath that works with resolved dual-root paths.
  * Convenience wrapper around ensureSquadPathDual.