diff --git a/lib/escrow-settlement.ts b/lib/escrow-settlement.ts
index 22e453f..2d157b9 100644
--- a/lib/escrow-settlement.ts
+++ b/lib/escrow-settlement.ts
@@ -11,10 +11,12 @@ import { z } from "zod"
 export const ESCROW_TIMEOUT_SECONDS = 86400 * 7 // 7 days
 export const DISPUTE_WINDOW_SECONDS = 86400 * 3 // 3 days
 export const MAX_ESCROW_AMOUNT = "100000000000" // 10000 PHASELQ in stroops
+// Amounts stay as strings so large stroop values never lose integer precision.
 
 // ── Type definitions ───────────────────────────────────────────────────────
 
 export const EscrowSchema = z.object({
+  // Schema validation is the boundary between untrusted API input and settlement logic.
   escrowId: z.string().min(1).max(128),
   buyer: z.string().length(56).regex(/^G[A-Z2-7]{55}$/),
   seller: z.string().length(56).regex(/^G[A-Z2-7]{55}$/),
@@ -109,6 +111,7 @@ export class EscrowSettlementError extends Error {
 export function validateEscrowCreation(
   escrow: CreateEscrow
 ): { valid: true } | { valid: false; error: string; code: string } {
+  // Validate the complete payload before applying cross-field business rules.
   const parsed = CreateEscrowSchema.safeParse(escrow)
   if (!parsed.success) {
     return {
@@ -120,6 +123,7 @@ export function validateEscrowCreation(
 
   // Validate parties are unique
   const parties = [escrow.buyer, escrow.seller, escrow.arbiter]
+  // A distinct arbiter prevents one participant from controlling every signature.
   const uniqueParties = new Set(parties)
   if (uniqueParties.size !== 3) {
     return {
@@ -132,6 +136,7 @@ export function validateEscrowCreation(
   // Validate amount
   try {
     const amountBI = BigInt(escrow.amount)
+    // BigInt comparisons keep the maximum check exact for on-chain-sized amounts.
     const maxBI = BigInt(MAX_ESCROW_AMOUNT)
     
     if (amountBI <= BigInt(0)) {
@@ -167,6 +172,7 @@ export function validateEscrowSignature(
   signature: SignEscrow,
   escrow: Escrow
 ): { valid: true } | { valid: false; error: string; code: string } {
+  // Signature validation is intentionally separate from transaction submission.
   const parsed = SignEscrowSchema.safeParse(signature)
   if (!parsed.success) {
     return {
@@ -187,6 +193,7 @@ export function validateEscrowSignature(
 
   // Check signer authorization
   const authorizedSigners = [escrow.buyer, escrow.seller, escrow.arbiter]
+  // Only the three parties recorded at creation may participate in consensus.
   if (!authorizedSigners.includes(signature.signer)) {
     return {
       valid: false,
@@ -197,6 +204,7 @@ export function validateEscrowSignature(
 
   // Check if already signed
   const existingSignature = escrow.signatures.find((s) => s.signer === signature.signer)
+  // A signer cannot change their decision by submitting a second record.
   if (existingSignature) {
     return {
       valid: false,
@@ -228,6 +236,7 @@ export function hasReachedConsensus(escrow: Escrow): {
   approvals: number
   rejections: number
 } {
+  // Approval and rejection thresholds are evaluated independently for 2-of-3 voting.
   const approvals = escrow.signatures.filter((s) => s.decision === "approve").length
   const rejections = escrow.signatures.filter((s) => s.decision === "reject").length
 
@@ -308,6 +317,7 @@ export function determineSettlement(escrow: Escrow): {
   outcome: "complete" | "refund" | "expire" | "pending"
   reason: string
 } {
+  // Settlement checks expiration first so an unfunded consensus cannot revive a timeout.
   // Check expiration
   if (isEscrowExpired(escrow) && escrow.status === "funded") {
     return {
diff --git a/lib/feature-flags.ts b/lib/feature-flags.ts
index 6c13499..cf622d8 100644
--- a/lib/feature-flags.ts
+++ b/lib/feature-flags.ts
@@ -154,17 +154,22 @@ const FLAG_ENV_MAP: Record<PhaseFeatureFlag, string[]> = {
 };
 
 function isTruthy(v: string | undefined): boolean {
+  // Accept common deployment-system spellings while keeping unset values disabled.
   if (!v) return false;
   const s = v.trim().toLowerCase();
+  // Lowercasing makes environment configuration case-insensitive.
   return s === "1" || s === "true" || s === "yes" || s === "on";
 }
 
 export function isFeatureEnabled(flag: PhaseFeatureFlag): boolean {
+  // Public keys are checked first so the same helper works in browser and server code.
   const keys = FLAG_ENV_MAP[flag] ?? [
     `NEXT_PUBLIC_FEATURE_${flag.replace(/-/g, "_").toUpperCase()}`,
     `FEATURE_${flag.replace(/-/g, "_").toUpperCase()}`,
   ];
+  // Unknown flags still receive a predictable convention-based fallback.
   for (const k of keys) {
+    // Reading process.env defensively keeps this module safe during client bundling.
     const v =
       typeof process !== "undefined"
         ? (process.env as Record<string, string | undefined>)[k]
@@ -175,6 +180,7 @@ export function isFeatureEnabled(flag: PhaseFeatureFlag): boolean {
 }
 
 export function featureFlagEnvKeys(flag: PhaseFeatureFlag): string[] {
+  // Exposing the exact keys lets diagnostics explain how to enable a flag.
   return FLAG_ENV_MAP[flag]
     ? [...FLAG_ENV_MAP[flag]]
     : [
@@ -184,6 +190,7 @@ export function featureFlagEnvKeys(flag: PhaseFeatureFlag): string[] {
 }
 
 export function getEnabledFeatureFlags(): PhaseFeatureFlag[] {
+  // Keep enumeration explicit so dashboards have stable, reviewable flag order.
   const all: PhaseFeatureFlag[] = [
     "phase-66",
     "phase-77",
@@ -234,10 +241,13 @@ export function getEnabledFeatureFlags(): PhaseFeatureFlag[] {
     "phase-140",
     "phase-141",
   ];
+  // Filtering is evaluated at call time, allowing runtime test overrides.
   return all.filter(isFeatureEnabled)
 }
 
 export function flagRollbackNote(flag: PhaseFeatureFlag): string {
+  // Rollback guidance is generated from the same key mapping used for activation.
+  // Returning a plain sentence keeps the note suitable for logs and admin screens.
   const keys = featureFlagEnvKeys(flag).join(" / ");
   return `Rollback ${flag}: unset ${keys} or set to 0/false and restart. No data migration to revert.`;
 }
diff --git a/lib/gateway-health.ts b/lib/gateway-health.ts
index ea4e6db..9f29f65 100644
--- a/lib/gateway-health.ts
+++ b/lib/gateway-health.ts
@@ -41,6 +41,7 @@ type InternalSample = { latencyMs: number; ok: boolean; at: number }
 const MAX_SAMPLES_PER_GATEWAY = 50
 const SCORE_LATENCY_WEIGHT = 0.6
 const SCORE_UPTIME_WEIGHT = 0.4
+// Keeping samples bounded prevents a long-lived server from growing without limit.
 
 // In-memory store (per-process). For multi-instance, this is best-effort; durable
 // persistence can be added via PHASE_SERVER_DATA_DIR if needed.
@@ -48,12 +49,14 @@ const samples = new Map<string, InternalSample[]>()
 const lastStatus = new Map<string, { ok: boolean; latencyMs: number; at: number }>()
 
 function percentile(sorted: number[], p: number): number {
+  // Callers sort first so percentile lookup remains a constant-time index operation.
   if (sorted.length === 0) return 0
   const idx = Math.ceil((p / 100) * sorted.length) - 1
   return sorted[Math.max(0, Math.min(idx, sorted.length - 1))] ?? 0
 }
 
 function scoreFor(latencies: number[], uptime: number): number {
+  // A neutral score avoids prematurely ranking an untested gateway as best or worst.
   if (latencies.length === 0) return 50
   const avg = latencies.reduce((a, b) => a + b, 0) / latencies.length
   // Map avg latency to 0-100: 0ms=100, 500ms=80, 2000ms=40, 5000ms=10, 8000ms=0
@@ -64,20 +67,24 @@ function scoreFor(latencies: number[], uptime: number): number {
   else latencyScore = Math.max(0, 20 - ((avg - 4000) / 4000) * 20) // 0-20
 
   const uptimeScore = uptime * 100
+  // Latency and availability are blended so one fast failure cannot look healthy.
   const raw = latencyScore * SCORE_LATENCY_WEIGHT + uptimeScore * SCORE_UPTIME_WEIGHT
   return Math.max(0, Math.min(100, Math.round(raw)))
 }
 
 function normalizeGateway(gateway: string): string {
+  // Canonical URLs prevent duplicate entries caused only by trailing slashes.
   return gateway.trim().replace(/\/+$/, "")
 }
 
 export function recordGatewayLatency(gateway: string, latencyMs: number, ok: boolean): void {
+  // The feature gate makes instrumentation removable without changing callers.
   if (!isFeatureEnabled("phase-121") && process.env.NODE_ENV !== "test") {
     // Still record in test; otherwise no-op when flag off to avoid overhead
     return
   }
   const key = normalizeGateway(gateway)
+  // Clamp negative measurements from malformed timers before scoring them.
   const list = samples.get(key) ?? []
   list.push({ latencyMs: Math.max(0, latencyMs), ok, at: Date.now() })
   if (list.length > MAX_SAMPLES_PER_GATEWAY) list.shift()
@@ -86,6 +93,7 @@ export function recordGatewayLatency(gateway: string, latencyMs: number, ok: boo
 }
 
 export function getGatewayHealthSnapshot(): GatewayHealthSnapshot {
+  // Build a fresh snapshot so consumers cannot mutate the internal maps.
   const enabled = isFeatureEnabled("phase-121")
   const entries: GatewayHealthEntry[] = []
 
@@ -143,6 +151,7 @@ export function getGatewayHealthSnapshot(): GatewayHealthSnapshot {
   }
 
   entries.sort((a, b) => b.score - a.score)
+  // Sorted entries make the first and last values the best and worst candidates.
 
   return {
     enabled,
@@ -161,6 +170,7 @@ export function getGatewayRanking(): string[] {
 }
 
 export function resetGatewayHealth(): void {
+  // Tests and operational resets need to clear both samples and latest status.
   samples.clear()
   lastStatus.clear()
 }
diff --git a/lib/json-store.ts b/lib/json-store.ts
index 34d7f19..7695ee6 100644
--- a/lib/json-store.ts
+++ b/lib/json-store.ts
@@ -39,6 +39,7 @@ import { serverDataJsonPath, type ServerDataFile } from "@/lib/server-data-paths
  */
 
 const fileQueues = new Map<string, Promise<unknown>>();
+// The queue key is the normalized absolute path supplied by each store.
 
 /**
  * Runs `task` with exclusive access to `filePath` within this process. Pairing
@@ -50,6 +51,7 @@ export function withFileLock<T>(
   filePath: string,
   task: () => Promise<T>,
 ): Promise<T> {
+  // Reusing the previous promise preserves mutation order for this file.
   const previous = fileQueues.get(filePath) ?? Promise.resolve();
   const next = previous.then(task, task);
   fileQueues.set(
@@ -63,6 +65,7 @@ export function withFileLock<T>(
 }
 
 function isErrnoCode(error: unknown, code: string): boolean {
+  // Error-shape checking stays local so callers can remain platform-neutral.
   return (
     typeof error === "object" &&
     error !== null &&
@@ -78,6 +81,7 @@ export async function readJsonFile<T>(
   filePath: string,
   fallback: T,
 ): Promise<T> {
+  // Reads remain unlocked because they never mutate shared state.
   let raw: string;
   try {
     raw = await readFile(filePath, "utf8");
@@ -101,10 +105,13 @@ export async function writeJsonFileAtomic(
   filePath: string,
   data: unknown,
 ): Promise<void> {
+  // The temporary sibling keeps rename atomic on the same filesystem.
   await mkdir(path.dirname(filePath), { recursive: true });
   const tmpPath = `${filePath}.${process.pid}.${Date.now().toString(36)}.tmp`;
+  // A process-and-time suffix avoids collisions between simultaneous writers.
   try {
     await writeFile(tmpPath, JSON.stringify(data, null, 2), "utf8");
+    // Rename is the commit point: readers see either the old file or the new one.
     await rename(tmpPath, filePath);
   } catch (error) {
     await rm(tmpPath, { force: true }).catch(() => undefined);
@@ -127,12 +134,14 @@ export async function updateJsonFile<T, R>(
     mutate: (store: T) => R | Promise<R>;
   },
 ): Promise<R> {
+  // Both read and write must stay inside one lock to prevent lost updates.
   return withFileLock(filePath, async () => {
     const raw = await readJsonFile<unknown>(filePath, undefined);
     // A missing file starts from an empty store, matching the
     // `catch { return {} }` readers this replaces.
     const store = opts.read ? opts.read(raw) : ((raw ?? {}) as T);
     const result = await opts.mutate(store);
+    // Persist only after the callback succeeds, so failed mutations are not saved.
     await writeJsonFileAtomic(filePath, store);
     return result;
   });
@@ -163,5 +172,6 @@ export function readStore<T extends object>(
   key: ServerDataFile,
   fallback: () => T,
 ): Promise<T> {
+  // Registered stores resolve their path through one shared server-data policy.
   return readJsonFile<T>(serverDataJsonPath(key), fallback());
 }
diff --git a/lib/phase-protocol.ts b/lib/phase-protocol.ts
index 99fe0c0..21bb857 100644
--- a/lib/phase-protocol.ts
+++ b/lib/phase-protocol.ts
@@ -34,11 +34,13 @@ export { recordGatewayLatency, getGatewayHealthSnapshot, getGatewayRanking, rese
 export type { GatewayHealthEntry, GatewayHealthSnapshot } from "@/lib/gateway-health"
 
 function isPhase121Enabled(): boolean {
+  // This local check keeps the dashboard gate usable before feature-flag initialization.
   const v = (typeof process !== "undefined" ? (process.env.NEXT_PUBLIC_FEATURE_PHASE_121 ?? process.env.FEATURE_PHASE_121 ?? "") : "")?.trim().toLowerCase()
   return v === "1" || v === "true" || v === "yes" || v === "on"
 }
 // Light wrapper for dashboard consumers (adds flag context, structured error)
 export function getGatewayHealthDashboardSafe(): { enabled: boolean; snapshot: import("@/lib/gateway-health").GatewayHealthSnapshot | null; error: string | null } {
+  // UI callers receive structured state instead of handling a thrown dashboard error.
   if (!isPhase121Enabled()) return { enabled: false, snapshot: null, error: "phase-121 flag disabled (set NEXT_PUBLIC_FEATURE_PHASE_121=1)" }
   try {
     return { enabled: true, snapshot: _getGatewayHealthSnapshot(), error: null }
@@ -68,6 +70,7 @@ function sorobanContractIdFromEnv(
   fallback: string,
   settingName: string,
 ): string {
+  // Prefer the first configured key, then validate the resolved value uniformly.
   const raw = envKeys.map((k) => k?.trim()).find((v) => v && v.length > 0)
   const id = raw ?? fallback
   if (StrKey.isValidContract(id)) return id
@@ -83,6 +86,7 @@ function sorobanContractIdFromEnv(
 }
 
 export const CONTRACT_ID = (() => {
+  // Client bundles must use public environment variables to avoid hydration drift.
   const e = (typeof process !== "undefined" ? process.env : {}) as NodeJS.ProcessEnv
   // Solo NEXT_PUBLIC_*: PHASE_PROTOCOL_ID (sin prefijo) no existe en el bundle del cliente → hydration mismatch.
   return sorobanContractIdFromEnv(
@@ -97,6 +101,7 @@ export const CONTRACT_ID = (() => {
  * No uses esto en componentes cliente.
  */
 export function phaseProtocolContractIdForServer(): string {
+  // Server routes may additionally read the non-public protocol ID override.
   const e = process.env
   return sorobanContractIdFromEnv(
     [e.NEXT_PUBLIC_PHASE_PROTOCOL_ID, e.PHASE_PROTOCOL_ID],
@@ -107,6 +112,7 @@ export function phaseProtocolContractIdForServer(): string {
 
 /** Contrato PHASE (NFT de utilidad) en Stellar Expert — testnet */
 export function stellarExpertTestnetContractUrl(contractId: string = CONTRACT_ID) {
+  // Centralizing explorer links keeps network selection consistent across the UI.
   return `https://stellar.expert/explorer/testnet/contract/${contractId}`
 }
 
@@ -179,6 +185,7 @@ export const RPC_URL = "https://soroban-testnet.stellar.org"
  * o deja que se infiera desde `<script src="…/_next/…">` (reverse proxy sin `basePath` en next.config).
  */
 function inferClientBasePathFromNextScripts(): string {
+  // Script URLs reveal a reverse-proxy subpath when Next.js has no explicit basePath.
   if (typeof document === "undefined") return ""
   const scripts = document.getElementsByTagName("script")
   for (let i = 0; i < scripts.length; i++) {
@@ -197,6 +204,7 @@ function inferClientBasePathFromNextScripts(): string {
 }
 
 function effectiveSorobanRpcUrl(): string {
+  // Browser requests prefer the same-origin proxy because public Soroban RPC lacks CORS.
   if (typeof window !== "undefined") {
     const pub = process.env.NEXT_PUBLIC_SOROBAN_RPC_PROXY_URL?.trim()
     if (pub && /^https?:\/\//i.test(pub)) return pub
@@ -322,6 +330,7 @@ export const READONLY_SIM_SOURCE_G =
 
 /** El SDK rechaza URLs `http://` (p. ej. `http://localhost:3000/api/soroban-rpc`) sin este flag. */
 function newRpcServerForUrl(url: string): rpc.Server {
+  // The SDK requires an explicit opt-in for local HTTP endpoints.
   const allowHttp = url.toLowerCase().startsWith("http://")
   return new rpc.Server(url, allowHttp ? { allowHttp: true } : undefined)
 }
@@ -329,6 +338,7 @@ function newRpcServerForUrl(url: string): rpc.Server {
 let _rpcServer: rpc.Server | null = null
 let _cachedRpcUrl: string | null = null
 function getRpc(): rpc.Server {
+  // Reuse the RPC client until configuration changes, avoiding needless connections.
   const url = effectiveSorobanRpcUrl()
   if (_rpcServer && _cachedRpcUrl === url) return _rpcServer
   _cachedRpcUrl = url