diff --git a/PLATFORM.md b/PLATFORM.md
index 25a1abe37..68df7e015 100644
--- a/PLATFORM.md
+++ b/PLATFORM.md
@@ -54,6 +54,15 @@ This document tracks all platform-specific code and dependencies across PAI, pro
    - **Fix:** Updated to reflect Linux is fully supported
    - **Status:** Documentation now accurate
 
+6a. ✅ `Pulse` vs `PULSE` directory casing mismatch
+   - **Files:** `Releases/v5.0.0/.claude/PAI/PULSE/{run-job,lib,setup,pulse-unified}.ts`,
+     `PULSE/modules/{imessage,user-index}.ts`, `PULSE/Performance/cost-aggregator.ts`,
+     `PULSE/checks/{notification-governor,poller-meta-monitor,github-work}.ts`,
+     `PULSE/Observability/observability.ts` (11 files, 14 occurrences)
+   - **Issue:** Source referenced `~/.claude/PAI/Pulse/...` but directory on disk is `PULSE`. Worked on macOS APFS (case-insensitive default) but broke on Linux ext4 and case-sensitive APFS — config and state lookups silently missed.
+   - **Fix:** Aligned all `path.join(...)` literals to `"PULSE"`.
+   - **Tested:** Linux (Ubuntu, runtime-verified). Behavior unchanged on case-insensitive filesystems (macOS default, NTFS).
+
 ---
 
 ### 📋 ALREADY HANDLED (No Action Needed)
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/Observability/observability.ts b/Releases/v5.0.0/.claude/PAI/PULSE/Observability/observability.ts
index 984c1b448..a55180e93 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/Observability/observability.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/Observability/observability.ts
@@ -66,7 +66,7 @@ const SECURITY_LOG_DIR = join(MEMORY_DIR, "SECURITY")
 const SETTINGS_PATH = join(HOME, ".claude", "settings.json")
 const LADDER_DIR = join(HOME, "Projects", "Ladder")
 
-const DEFAULT_DASHBOARD_DIR = join(PAI_DIR, "Pulse", "Observability", "out")
+const DEFAULT_DASHBOARD_DIR = join(PAI_DIR, "PULSE", "Observability", "out")
 
 // ── In-Memory Store (hook-pushed state/events) ──
 
@@ -149,7 +149,7 @@ function getDashboardDir(): string {
   const dir = config.dashboard_dir ?? DEFAULT_DASHBOARD_DIR
   // Resolve relative paths against Pulse directory
   if (!dir.startsWith("/")) {
-    return join(HOME, ".claude", "PAI", "Pulse", dir)
+    return join(HOME, ".claude", "PAI", "PULSE", dir)
   }
   return dir
 }
@@ -1647,7 +1647,7 @@ function readDirMdFiles(dir: string): { name: string, content: string, sections:
 function handleUserIndexApi(filter: string | null): Response {
   try {
     const PAI_DIR = process.env.PAI_DIR || join(process.env.HOME || "", ".claude", "PAI")
-    const indexPath = join(PAI_DIR, "Pulse", "state", "user-index.json")
+    const indexPath = join(PAI_DIR, "PULSE", "state", "user-index.json")
     const raw = Bun.file(indexPath)
     if (!raw.size) {
       return Response.json(
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/Performance/cost-aggregator.ts b/Releases/v5.0.0/.claude/PAI/PULSE/Performance/cost-aggregator.ts
index f6c5af5ce..727620fab 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/Performance/cost-aggregator.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/Performance/cost-aggregator.ts
@@ -17,7 +17,7 @@ const HOME = process.env.HOME ?? ""
 const PAI_DIR = join(HOME, ".claude", "PAI")
 const PROJECTS_DIR = join(HOME, ".claude", "projects")
 const OUTPUT_FILE = join(PAI_DIR, "MEMORY", "OBSERVABILITY", "session-costs.jsonl")
-const STATE_FILE = join(PAI_DIR, "Pulse", "Performance", "aggregator-state.json")
+const STATE_FILE = join(PAI_DIR, "PULSE", "Performance", "aggregator-state.json")
 
 // Model pricing per million tokens (as of 2026-04)
 const MODEL_PRICING: Record<string, { input: number; output: number; cacheWrite: number; cacheRead: number }> = {
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/checks/github-work.ts b/Releases/v5.0.0/.claude/PAI/PULSE/checks/github-work.ts
index 78782f17d..79ad44953 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/checks/github-work.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/checks/github-work.ts
@@ -14,7 +14,7 @@ import { parse } from "smol-toml"
 import { SignJWT, importPKCS8 } from "jose"
 
 const HOME = process.env.HOME ?? ""
-const PULSE_DIR = join(HOME, ".claude", "PAI", "Pulse")
+const PULSE_DIR = join(HOME, ".claude", "PAI", "PULSE")
 const STATE_FILE = join(PULSE_DIR, "state", "work-token.json")
 
 // ── Worker Config (from PULSE.toml [worker] section) ──
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/checks/notification-governor.ts b/Releases/v5.0.0/.claude/PAI/PULSE/checks/notification-governor.ts
index fb1a62ea3..6947efa48 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/checks/notification-governor.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/checks/notification-governor.ts
@@ -34,7 +34,7 @@ import { createHash } from "crypto";
 
 const HOME = process.env.HOME || "";
 const PAI_DIR = process.env.PAI_DIR || join(HOME, ".claude", "PAI");
-const STATE_FILE = join(PAI_DIR, "Pulse", "state", "notification-governor.json");
+const STATE_FILE = join(PAI_DIR, "PULSE", "state", "notification-governor.json");
 const LOG_FILE = join(PAI_DIR, "MEMORY", "OBSERVABILITY", "notification-governor.jsonl");
 const NOTIFY_URL = "http://localhost:31337/notify";
 const VOICE_ID = "fTtv3eikoepIosk8dTZ5";
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/checks/poller-meta-monitor.ts b/Releases/v5.0.0/.claude/PAI/PULSE/checks/poller-meta-monitor.ts
index 5ca27d1c6..7340c8054 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/checks/poller-meta-monitor.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/checks/poller-meta-monitor.ts
@@ -20,8 +20,8 @@ import { join } from "path";
 
 const HOME = process.env.HOME || "";
 const PAI_DIR = process.env.PAI_DIR || join(HOME, ".claude", "PAI");
-const PULSE_STATE = join(PAI_DIR, "Pulse", "state", "state.json");
-const PULSE_TOML = join(PAI_DIR, "Pulse", "PULSE.toml");
+const PULSE_STATE = join(PAI_DIR, "PULSE", "state", "state.json");
+const PULSE_TOML = join(PAI_DIR, "PULSE", "PULSE.toml");
 
 // Jobs we specifically monitor — the Current→Ideal pipeline ones.
 const WATCHED_JOBS = [
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/lib.ts b/Releases/v5.0.0/.claude/PAI/PULSE/lib.ts
index 93d77fac6..8889825be 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/lib.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/lib.ts
@@ -246,7 +246,7 @@ export async function spawnScript(command: string, timeoutMs = 60_000): Promise<
   const proc = Bun.spawn(["bash", "-c", command], {
     stdout: "pipe",
     stderr: "pipe",
-    cwd: join(process.env.HOME ?? "~", ".claude", "PAI", "Pulse"),
+    cwd: join(process.env.HOME ?? "~", ".claude", "PAI", "PULSE"),
     env: { ...process.env },
   })
 
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/modules/imessage.ts b/Releases/v5.0.0/.claude/PAI/PULSE/modules/imessage.ts
index c6fe58bce..32e3d3a99 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/modules/imessage.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/modules/imessage.ts
@@ -60,8 +60,8 @@ export interface IMessageHealth {
 
 const HOME = process.env.HOME ?? ""
 const CWD = join(HOME, ".claude")
-const STATE_DIR = join(HOME, ".claude", "PAI", "Pulse", "state", "imessage")
-const LOGS_DIR = join(HOME, ".claude", "PAI", "Pulse", "logs", "imessage")
+const STATE_DIR = join(HOME, ".claude", "PAI", "PULSE", "state", "imessage")
+const LOGS_DIR = join(HOME, ".claude", "PAI", "PULSE", "logs", "imessage")
 
 let pollTimer: ReturnType<typeof setInterval> | null = null
 let running = false
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/modules/user-index.ts b/Releases/v5.0.0/.claude/PAI/PULSE/modules/user-index.ts
index 7ee19c501..aac3f1dda 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/modules/user-index.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/modules/user-index.ts
@@ -25,7 +25,7 @@ import { join, relative, basename, dirname } from "path"
 const HOME = process.env.HOME ?? ""
 const PAI_DIR = process.env.PAI_DIR || join(HOME, ".claude", "PAI")
 const USER_DIR = join(PAI_DIR, "USER")
-const STATE_DIR = join(PAI_DIR, "Pulse", "state")
+const STATE_DIR = join(PAI_DIR, "PULSE", "state")
 const INDEX_PATH = join(STATE_DIR, "user-index.json")
 const MODULE_NAME = "user-index"
 
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/pulse-unified.ts b/Releases/v5.0.0/.claude/PAI/PULSE/pulse-unified.ts
index ad45bd166..bac9cfa6e 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/pulse-unified.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/pulse-unified.ts
@@ -22,7 +22,7 @@ import { parse } from "smol-toml"
 
 const HOME = process.env.HOME ?? "~"
 const PAI_DIR = join(HOME, ".claude", "PAI")
-const PULSE_DIR = join(PAI_DIR, "Pulse")
+const PULSE_DIR = join(PAI_DIR, "PULSE")
 
 const envPath = join(HOME, ".claude", ".env")
 try {
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/run-job.ts b/Releases/v5.0.0/.claude/PAI/PULSE/run-job.ts
index de5b6f50a..afaf35783 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/run-job.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/run-job.ts
@@ -31,7 +31,7 @@ if (!jobName) {
   process.exit(1)
 }
 
-const PULSE_DIR = join(process.env.HOME ?? "~", ".claude", "PAI", "Pulse")
+const PULSE_DIR = join(process.env.HOME ?? "~", ".claude", "PAI", "PULSE")
 const config = await loadConfig(PULSE_DIR)
 const job = config.jobs.find((j) => j.name === jobName)
 if (!job) {
diff --git a/Releases/v5.0.0/.claude/PAI/PULSE/setup.ts b/Releases/v5.0.0/.claude/PAI/PULSE/setup.ts
index a743ea2f3..44fe69136 100644
--- a/Releases/v5.0.0/.claude/PAI/PULSE/setup.ts
+++ b/Releases/v5.0.0/.claude/PAI/PULSE/setup.ts
@@ -15,7 +15,7 @@ import { existsSync, mkdirSync } from "fs"
 
 const HOME = process.env.HOME ?? "~"
 const PAI_DIR = join(HOME, ".claude", "PAI")
-const PULSE_DIR = join(PAI_DIR, "Pulse")
+const PULSE_DIR = join(PAI_DIR, "PULSE")
 
 // ── Helpers ──