diff --git a/AGENTS.md b/AGENTS.md
index 6fa58c42f5..b120f30bcd 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -132,7 +132,7 @@ All persistence uses SQLite through domain-specific modules:
 `backup.ts`, `proxies.ts`, `prompts.ts`, `webhooks.ts`, `detailedLogs.ts`,
 `domainState.ts`, `registeredKeys.ts`, `quotaSnapshots.ts`, `modelComboMappings.ts`,
 `cliToolState.ts`, `encryption.ts`, `readCache.ts`, `secrets.ts`, `stateReset.ts`,
-`contextHandoffs.ts`.
+`contextHandoffs.ts`, `compression.ts`.
 Schema migrations live in `db/migrations/` and run via `migrationRunner.ts`.
 `src/lib/localDb.ts` is a **re-export layer only** — never add logic there.
 
@@ -142,7 +142,7 @@ Schema migrations live in `db/migrations/` and run via `migrationRunner.ts`.
   journaling. `SCHEMA_SQL` defines 15 base tables. Helpers: `rowToCamel`, `encryptConnectionFields`.
 - **`migrationRunner.ts`**: Applies versioned SQL files from `db/migrations/` inside transactions.
   Tracks applied migrations in `_omniroute_migrations` table.
-- **Migrations**: 21 files (`001_initial_schema.sql` → `021_combo_call_log_targets.sql`).
+- **Migrations**: 22 files (`001_initial_schema.sql` → `022_compression_settings.sql`).
   Each migration is idempotent and runs in a transaction.
 - **Domain modules** import `getDbInstance()` from `core.ts` for all CRUD operations.
   Each module owns a specific table/set of tables (e.g., `providers.ts` → `provider_connections`,
@@ -285,7 +285,24 @@ Includes request/response translators with helpers for image handling.
 `autoCombo/`, `intentClassifier.ts`, `taskAwareRouter.ts`, `thinkingBudget.ts`,
 `contextManager.ts`, `modelDeprecation.ts`, `modelFamilyFallback.ts`,
 `emergencyFallback.ts`, `workflowFSM.ts`, `backgroundTaskDetector.ts`, `ipFilter.ts`,
-`signatureCache.ts`, `volumeDetector.ts`, `contextHandoff.ts`, and more.
+`signatureCache.ts`, `volumeDetector.ts`, `contextHandoff.ts`, `compression/` (prompt
+compression pipeline), and more.
+
+#### Prompt Compression Pipeline (`compression/`)
+
+Modular prompt compression that runs proactively before the existing reactive context manager.
+
+- **`strategySelector.ts`**: Selects compression mode based on config, combo overrides, auto-trigger
+  thresholds. Priority: combo override > auto-trigger > default mode > off.
+- **`lite.ts`**: 5 lite-mode techniques: `collapseWhitespace`, `dedupSystemPrompt`,
+  `compressToolResults`, `removeRedundantContent`, `replaceImageUrls`. Target: 10-15% savings at
+  <1ms latency.
+- **`stats.ts`**: Per-request compression stats tracking (original tokens, compressed tokens,
+  savings %, techniques used).
+- **`types.ts`**: `CompressionMode` (off/lite/standard/aggressive/ultra), `CompressionConfig`,
+  `CompressionStats`, `CompressionResult`.
+- DB settings in `src/lib/db/compression.ts`, API route at `src/app/api/settings/compression/`.
+- Phase 1 implements lite mode only; standard/aggressive/ultra are placeholders for Phase 2.
 
 #### Combo Routing Engine (`combo.ts`)
 
diff --git a/open-sse/config/providerHeaderProfiles.ts b/open-sse/config/providerHeaderProfiles.ts
index 301053cb04..69c591652d 100644
--- a/open-sse/config/providerHeaderProfiles.ts
+++ b/open-sse/config/providerHeaderProfiles.ts
@@ -53,7 +53,9 @@ function getRuntimePlatform(): string {
 }
 
 function getRuntimeArch(): string {
-  return typeof process !== "undefined" && typeof process.arch === "string" ? process.arch : "unknown";
+  return typeof process !== "undefined" && typeof process.arch === "string"
+    ? process.arch
+    : "unknown";
 }
 
 function getRuntimeVersion(): string {
diff --git a/open-sse/handlers/chatCore.ts b/open-sse/handlers/chatCore.ts
index 9317c55d98..cf9bd81634 100644
--- a/open-sse/handlers/chatCore.ts
+++ b/open-sse/handlers/chatCore.ts
@@ -1560,7 +1560,38 @@ export async function handleChatCore({
   const allMessages =
     body?.messages || body?.input || body?.contents || body?.request?.contents || [];
   if (body && Array.isArray(allMessages) && allMessages.length > 0) {
-    const estimatedTokens = estimateTokens(JSON.stringify(allMessages));
+    let estimatedTokens = estimateTokens(JSON.stringify(allMessages));
+
+    // --- Modular Compression Pipeline (Phase 1: Lite mode) ---
+    // Runs BEFORE the existing reactive compressContext() to proactively reduce tokens.
+    try {
+      const { getCompressionSettings } = await import("../../src/lib/db/compression.ts");
+      const { selectCompressionStrategy, applyCompression } =
+        await import("../services/compression/strategySelector.ts");
+      const { trackCompressionStats } = await import("../services/compression/stats.ts");
+      const config = await getCompressionSettings();
+      const mode = selectCompressionStrategy(config, comboName ?? null, estimatedTokens);
+      if (mode !== "off") {
+        const result = applyCompression(body, mode, { model: effectiveModel });
+        if (result.compressed && result.stats) {
+          body = result.body as typeof body;
+          estimatedTokens = result.stats.compressedTokens;
+          trackCompressionStats(result.stats);
+          log?.info?.(
+            "COMPRESSION",
+            `Prompt compressed (${mode}): ${result.stats.originalTokens} -> ${result.stats.compressedTokens} tokens (${result.stats.savingsPercent}% saved, techniques: ${result.stats.techniquesUsed.join(",")})`
+          );
+        }
+      }
+    } catch (err) {
+      log?.warn?.(
+        "COMPRESSION",
+        "Compression pipeline error (non-fatal): " +
+          (err instanceof Error ? err.message : String(err))
+      );
+    }
+    // --- End Modular Compression Pipeline ---
+
     let contextLimit = getTokenLimit(provider, effectiveModel);
 
     if (isCombo && comboName) {
diff --git a/open-sse/services/AGENTS.md b/open-sse/services/AGENTS.md
index 9dd5092ef7..b7b99308d0 100644
--- a/open-sse/services/AGENTS.md
+++ b/open-sse/services/AGENTS.md
@@ -48,6 +48,16 @@
 - **`volumeDetector.ts`** — Detects request volume spikes; triggers rate-limit escalation or load-shedding.
 - **`contextHandoff.ts`** — Serializes/restores session context for agent handoff (A2A protocol).
 
+### Prompt Compression Pipeline
+
+- **`compression/`** — Modular prompt compression running proactively before `contextManager.ts`.
+  - `strategySelector.ts` — Selects mode (off/lite/standard/aggressive/ultra) with combo overrides and auto-trigger.
+  - `lite.ts` — 5 lite techniques: whitespace collapse, system prompt dedup, tool result truncation, redundant removal, image URL placeholder.
+  - `stats.ts` — Per-request compression stats (original/compressed tokens, savings %, techniques).
+  - `types.ts` — Shared types (`CompressionMode`, `CompressionConfig`, `CompressionStats`, `CompressionResult`).
+  - `index.ts` — Barrel re-exports.
+  - Phase 1: lite mode only. Standard/aggressive/ultra = Phase 2.
+
 ### Auto-Routing & Adaptive
 
 - **`autoCombo/`** — Auto-generates combo configs based on historical performance, cost, and latency.
diff --git a/open-sse/services/chatgptImageCache.ts b/open-sse/services/chatgptImageCache.ts
index 77f6759182..e6b5f8b874 100644
--- a/open-sse/services/chatgptImageCache.ts
+++ b/open-sse/services/chatgptImageCache.ts
@@ -67,10 +67,7 @@ function evictExpired(now = Date.now()): void {
 function evictUntilWithinLimits(maxBytes: number, incomingBytes: number): void {
   // Drop oldest until both the entry-count and total-byte caps are satisfied.
   // Map iteration is insertion-ordered so the first key is the oldest entry.
-  while (
-    (cache.size >= MAX_ENTRIES || cacheBytes + incomingBytes > maxBytes) &&
-    cache.size > 0
-  ) {
+  while ((cache.size >= MAX_ENTRIES || cacheBytes + incomingBytes > maxBytes) && cache.size > 0) {
     const firstKey = cache.keys().next().value;
     if (!firstKey) break;
     deleteEntry(firstKey);
@@ -122,9 +119,7 @@ export function getChatGptImageConversationContext(
  * saved chatgpt.com conversation node and actually edit the image instead
  * of generating an unrelated one from scratch.
  */
-export function findChatGptImageBySha256(
-  hash: string
-): { id: string; entry: CachedImage } | null {
+export function findChatGptImageBySha256(hash: string): { id: string; entry: CachedImage } | null {
   evictExpired();
   const target = hash.toLowerCase();
   for (const [id, entry] of cache.entries()) {
diff --git a/open-sse/services/compression/index.ts b/open-sse/services/compression/index.ts
new file mode 100644
index 0000000000..d1f69eb6af
--- /dev/null
+++ b/open-sse/services/compression/index.ts
@@ -0,0 +1,31 @@
+/**
+ * Compression Pipeline — Phase 1 (Lite mode)
+ *
+ * Modular prompt compression that runs BEFORE the existing reactive context manager.
+ * Lite mode: 5 techniques, ~10-15% token savings, <1ms latency.
+ */
+
+// Types
+export type {
+  CompressionMode,
+  CompressionConfig,
+  CompressionStats,
+  CompressionResult,
+} from "./types";
+export { DEFAULT_COMPRESSION_CONFIG } from "./types";
+
+// Lite compression techniques
+export {
+  applyLiteCompression,
+  collapseWhitespace,
+  dedupSystemPrompt,
+  compressToolResults,
+  removeRedundantContent,
+  replaceImageUrls,
+} from "./lite";
+
+// Strategy selector
+export { selectCompressionStrategy, getEffectiveMode, applyCompression } from "./strategySelector";
+
+// Stats tracking
+export { estimateCompressionTokens, createCompressionStats, trackCompressionStats } from "./stats";
diff --git a/open-sse/services/compression/lite.ts b/open-sse/services/compression/lite.ts
new file mode 100644
index 0000000000..bc64e13ef6
--- /dev/null
+++ b/open-sse/services/compression/lite.ts
@@ -0,0 +1,170 @@
+import type { CompressionResult, CompressionMode } from "./types";
+import { createCompressionStats } from "./stats";
+
+interface Message {
+  role: string;
+  content: string | Array<Record<string, unknown>>;
+  [key: string]: unknown;
+}
+
+interface ChatBody {
+  messages?: Message[];
+  [key: string]: unknown;
+}
+
+export function collapseWhitespace(body: ChatBody): {
+  body: ChatBody;
+  applied: boolean;
+} {
+  if (!body.messages) return { body, applied: false };
+  let applied = false;
+  const messages = body.messages.map((msg) => {
+    if (typeof msg.content !== "string") return msg;
+    const normalized = msg.content.replace(/\n{3,}/g, "\n\n").replace(/[ \t]+$/gm, "");
+    if (normalized !== msg.content) applied = true;
+    return { ...msg, content: normalized };
+  });
+  return { body: { ...body, messages }, applied };
+}
+
+export function dedupSystemPrompt(body: ChatBody): {
+  body: ChatBody;
+  applied: boolean;
+} {
+  if (!body.messages) return { body, applied: false };
+  const seen = new Set<string>();
+  let applied = false;
+  const messages = body.messages.filter((msg) => {
+    if (msg.role !== "system" || typeof msg.content !== "string") return true;
+    const key = msg.content.trim().slice(0, 200);
+    if (seen.has(key)) {
+      applied = true;
+      return false;
+    }
+    seen.add(key);
+    return true;
+  });
+  return { body: { ...body, messages }, applied };
+}
+
+export function compressToolResults(body: ChatBody): {
+  body: ChatBody;
+  applied: boolean;
+} {
+  if (!body.messages) return { body, applied: false };
+  const MAX_TOOL_LENGTH = 2000;
+  let applied = false;
+  const messages = body.messages.map((msg) => {
+    if (msg.role !== "tool" || typeof msg.content !== "string") return msg;
+    if (msg.content.length <= MAX_TOOL_LENGTH) return msg;
+    applied = true;
+    return {
+      ...msg,
+      content: msg.content.slice(0, MAX_TOOL_LENGTH) + "\n...[truncated]",
+    };
+  });
+  return { body: { ...body, messages }, applied };
+}
+
+export function removeRedundantContent(body: ChatBody): {
+  body: ChatBody;
+  applied: boolean;
+} {
+  if (!body.messages) return { body, applied: false };
+  let applied = false;
+  const messages: Message[] = [];
+  for (let i = 0; i < body.messages.length; i++) {
+    const msg = body.messages[i];
+    const contentStr = typeof msg.content === "string" ? msg.content : JSON.stringify(msg.content);
+    if (
+      i > 0 &&
+      body.messages[i - 1].role === msg.role &&
+      typeof body.messages[i - 1].content === "string" &&
+      body.messages[i - 1].content === contentStr
+    ) {
+      applied = true;
+      continue;
+    }
+    messages.push(msg);
+  }
+  return { body: { ...body, messages }, applied };
+}
+
+export function replaceImageUrls(
+  body: ChatBody,
+  model?: string
+): { body: ChatBody; applied: boolean } {
+  if (!body.messages) return { body, applied: false };
+  const isVisionModel = model && /\b(vision|gpt-4o|claude-3|gemini-1\.5|gemini-2)\b/i.test(model);
+  if (isVisionModel) return { body, applied: false };
+  let applied = false;
+  const messages = body.messages.map((msg) => {
+    if (!Array.isArray(msg.content)) return msg;
+    const newContent = msg.content.map((part) => {
+      if (
+        typeof part === "object" &&
+        part !== null &&
+        part.type === "image_url" &&
+        typeof (part as Record<string, unknown>).image_url === "object" &&
+        ((part as Record<string, unknown>).image_url as Record<string, unknown>)?.url
+      ) {
+        const url = String(
+          ((part as Record<string, unknown>).image_url as Record<string, unknown>).url
+        );
+        if (url.startsWith("data:image/")) {
+          applied = true;
+          const format = url.slice(url.indexOf("/") + 1, url.indexOf(";")) || "unknown";
+          return { type: "text", text: `[image: ${format}]` };
+        }
+      }
+      return part;
+    });
+    return { ...msg, content: newContent };
+  });
+  return { body: { ...body, messages }, applied };
+}
+
+export function applyLiteCompression(
+  body: Record<string, unknown>,
+  options?: { model?: string }
+): CompressionResult {
+  const originalBody = body;
+  let current = body as ChatBody;
+  const techniquesApplied: string[] = [];
+
+  const r1 = collapseWhitespace(current);
+  current = r1.body;
+  if (r1.applied) techniquesApplied.push("whitespace");
+
+  const r2 = dedupSystemPrompt(current);
+  current = r2.body;
+  if (r2.applied) techniquesApplied.push("system-dedup");
+
+  const r3 = compressToolResults(current);
+  current = r3.body;
+  if (r3.applied) techniquesApplied.push("tool-compress");
+
+  const r4 = removeRedundantContent(current);
+  current = r4.body;
+  if (r4.applied) techniquesApplied.push("redundant-remove");
+
+  const r5 = replaceImageUrls(current, options?.model);
+  current = r5.body;
+  if (r5.applied) techniquesApplied.push("image-placeholder");
+
+  const compressed = techniquesApplied.length > 0;
+  const stats = compressed
+    ? createCompressionStats(
+        originalBody,
+        current as Record<string, unknown>,
+        "lite",
+        techniquesApplied
+      )
+    : null;
+
+  return {
+    body: current as Record<string, unknown>,
+    compressed,
+    stats,
+  };
+}
diff --git a/open-sse/services/compression/stats.ts b/open-sse/services/compression/stats.ts
new file mode 100644
index 0000000000..5e84f0b22e
--- /dev/null
+++ b/open-sse/services/compression/stats.ts
@@ -0,0 +1,38 @@
+import type { CompressionStats, CompressionMode } from "./types";
+
+const CHARS_PER_TOKEN = 4;
+
+export function estimateCompressionTokens(text: string | object | null | undefined): number {
+  if (!text) return 0;
+  const str = typeof text === "string" ? text : JSON.stringify(text);
+  return Math.ceil(str.length / CHARS_PER_TOKEN);
+}
+
+export function createCompressionStats(
+  originalBody: Record<string, unknown>,
+  compressedBody: Record<string, unknown>,
+  mode: CompressionMode,
+  techniquesUsed: string[]
+): CompressionStats {
+  const originalTokens = estimateCompressionTokens(originalBody);
+  const compressedTokens = estimateCompressionTokens(compressedBody);
+  const savingsPercent =
+    originalTokens > 0
+      ? Math.round(((originalTokens - compressedTokens) / originalTokens) * 10000) / 100
+      : 0;
+  return {
+    originalTokens,
+    compressedTokens,
+    savingsPercent,
+    techniquesUsed,
+    mode,
+    timestamp: Date.now(),
+  };
+}
+
+export function trackCompressionStats(stats: CompressionStats): void {
+  if (stats.originalTokens <= 0) return;
+  console.log(
+    `[COMPRESSION] mode=${stats.mode} tokens=${stats.originalTokens}->${stats.compressedTokens} savings=${stats.savingsPercent}% techniques=${stats.techniquesUsed.join(",")}`
+  );
+}
diff --git a/open-sse/services/compression/strategySelector.ts b/open-sse/services/compression/strategySelector.ts
new file mode 100644
index 0000000000..0b89a32651
--- /dev/null
+++ b/open-sse/services/compression/strategySelector.ts
@@ -0,0 +1,51 @@
+import type { CompressionConfig, CompressionMode, CompressionResult } from "./types";
+import { applyLiteCompression } from "./lite";
+
+export function checkComboOverride(
+  config: CompressionConfig,
+  comboId: string | null
+): CompressionMode | null {
+  if (!comboId || !config.comboOverrides) return null;
+  return config.comboOverrides[comboId] ?? null;
+}
+
+export function shouldAutoTrigger(config: CompressionConfig, estimatedTokens: number): boolean {
+  return config.autoTriggerTokens > 0 && estimatedTokens >= config.autoTriggerTokens;
+}
+
+export function getEffectiveMode(
+  config: CompressionConfig,
+  comboId: string | null,
+  estimatedTokens: number
+): CompressionMode {
+  if (!config.enabled) return "off";
+
+  const comboMode = checkComboOverride(config, comboId);
+  if (comboMode) return comboMode;
+
+  if (shouldAutoTrigger(config, estimatedTokens)) return "lite";
+
+  return config.defaultMode;
+}
+
+export function selectCompressionStrategy(
+  config: CompressionConfig,
+  comboId: string | null,
+  estimatedTokens: number
+): CompressionMode {
+  return getEffectiveMode(config, comboId, estimatedTokens);
+}
+
+export function applyCompression(
+  body: Record<string, unknown>,
+  mode: CompressionMode,
+  options?: { model?: string }
+): CompressionResult {
+  if (mode === "off") {
+    return { body, compressed: false, stats: null };
+  }
+  if (mode === "lite") {
+    return applyLiteCompression(body, options);
+  }
+  return { body, compressed: false, stats: null };
+}
diff --git a/open-sse/services/compression/types.ts b/open-sse/services/compression/types.ts
new file mode 100644
index 0000000000..4d37d2f9a9
--- /dev/null
+++ b/open-sse/services/compression/types.ts
@@ -0,0 +1,45 @@
+/**
+ * Compression Pipeline Types — Phase 1 (Lite mode)
+ *
+ * Modular prompt compression that runs BEFORE the existing reactive context manager.
+ */
+
+/** Compression mode levels (only 'off' and 'lite' are active in Phase 1) */
+export type CompressionMode = "off" | "lite" | "standard" | "aggressive" | "ultra";
+
+/** Compression configuration stored in DB */
+export interface CompressionConfig {
+  enabled: boolean;
+  defaultMode: CompressionMode;
+  autoTriggerTokens: number;
+  cacheMinutes: number;
+  preserveSystemPrompt: boolean;
+  comboOverrides: Record<string, CompressionMode>;
+}
+
+/** Per-request compression statistics */
+export interface CompressionStats {
+  originalTokens: number;
+  compressedTokens: number;
+  savingsPercent: number;
+  techniquesUsed: string[];
+  mode: CompressionMode;
+  timestamp: number;
+}
+
+/** Result of a compression operation */
+export interface CompressionResult {
+  body: Record<string, unknown>;
+  compressed: boolean;
+  stats: CompressionStats | null;
+}
+
+/** Default compression config values */
+export const DEFAULT_COMPRESSION_CONFIG: CompressionConfig = {
+  enabled: false,
+  defaultMode: "off",
+  autoTriggerTokens: 0,
+  cacheMinutes: 5,
+  preserveSystemPrompt: true,
+  comboOverrides: {},
+};
diff --git a/open-sse/services/usage.ts b/open-sse/services/usage.ts
index 527774b13c..8c5ef39627 100644
--- a/open-sse/services/usage.ts
+++ b/open-sse/services/usage.ts
@@ -1230,7 +1230,11 @@ async function fetchAntigravityAvailableModelsCached(
 
   const cacheKey = buildAntigravityUsageCacheKey(accessToken, projectId);
   const cached = _antigravityAvailableModelsCache.get(cacheKey);
-  if (!options.forceRefresh && cached && Date.now() - cached.fetchedAt < ANTIGRAVITY_MODELS_CACHE_TTL_MS) {
+  if (
+    !options.forceRefresh &&
+    cached &&
+    Date.now() - cached.fetchedAt < ANTIGRAVITY_MODELS_CACHE_TTL_MS
+  ) {
     return cached.data;
   }
 
@@ -1361,25 +1365,31 @@ async function probeAntigravityCreditBalance(
 
   const cacheKey = buildAntigravityUsageCacheKey(accessToken, projectId || accountId);
   const cached = _antigravityCreditProbeCache.get(cacheKey);
-  if (!options.forceRefresh && cached && Date.now() - cached.fetchedAt < ANTIGRAVITY_CREDIT_PROBE_TTL_MS) {
+  if (
+    !options.forceRefresh &&
+    cached &&
+    Date.now() - cached.fetchedAt < ANTIGRAVITY_CREDIT_PROBE_TTL_MS
+  ) {
     return cached.data;
   }
 
   const inflight = _antigravityCreditProbeInflight.get(cacheKey);
   if (inflight) return inflight;
 
-  const promise = probeAntigravityCreditBalanceUncached(accessToken, accountId, projectId).then(
-    (data) => {
-      _antigravityCreditProbeCache.set(cacheKey, { data, fetchedAt: Date.now() });
-      return data;
-    },
-    (error) => {
-      _antigravityCreditProbeCache.set(cacheKey, { data: null, fetchedAt: Date.now() });
-      throw error;
-    }
-  ).finally(() => {
-    _antigravityCreditProbeInflight.delete(cacheKey);
-  });
+  const promise = probeAntigravityCreditBalanceUncached(accessToken, accountId, projectId)
+    .then(
+      (data) => {
+        _antigravityCreditProbeCache.set(cacheKey, { data, fetchedAt: Date.now() });
+        return data;
+      },
+      (error) => {
+        _antigravityCreditProbeCache.set(cacheKey, { data: null, fetchedAt: Date.now() });
+        throw error;
+      }
+    )
+    .finally(() => {
+      _antigravityCreditProbeInflight.delete(cacheKey);
+    });
 
   _antigravityCreditProbeInflight.set(cacheKey, promise);
   return promise;
@@ -1501,7 +1511,12 @@ async function getAntigravityUsage(
     // If no cached balance and credits mode is enabled, fire a minimal probe
     const creditsMode = getCreditsMode();
     if ((options.forceRefresh || creditBalance === null) && creditsMode !== "off") {
-      creditBalance = await probeAntigravityCreditBalance(accessToken, accountId, projectId, options);
+      creditBalance = await probeAntigravityCreditBalance(
+        accessToken,
+        accountId,
+        projectId,
+        options
+      );
     }
 
     const data = await fetchAntigravityAvailableModelsCached(accessToken, projectId, options);
diff --git a/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx b/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx
index fff2b31ec3..e2c71e54d6 100644
--- a/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx
+++ b/src/app/(dashboard)/dashboard/api-manager/ApiManagerPageClient.tsx
@@ -183,15 +183,12 @@ export default function ApiManagerPageClient() {
 
       for (const key of apiKeys) {
         // Match analytics entry by key name (reliable across both systems)
-        const analyticsMatch = byApiKey.find(
-          (entry: any) => entry.apiKeyName === key.name
-        );
+        const analyticsMatch = byApiKey.find((entry: any) => entry.apiKeyName === key.name);
 
         // The call-logs endpoint returns entries sorted by timestamp DESC,
         // so the first match is the most recent one.
-        const lastUsed = (logs || []).find(
-          (log: any) => log.apiKeyName === key.name
-        )?.timestamp || null;
+        const lastUsed =
+          (logs || []).find((log: any) => log.apiKeyName === key.name)?.timestamp || null;
 
         stats[key.id] = {
           totalRequests: analyticsMatch?.requests ?? 0,
diff --git a/src/app/api/auth/login/route.ts b/src/app/api/auth/login/route.ts
index b5dbf270d0..396fdc63da 100644
--- a/src/app/api/auth/login/route.ts
+++ b/src/app/api/auth/login/route.ts
@@ -10,11 +10,7 @@ import {
 } from "@/lib/auth/managementPassword";
 import { loginSchema } from "@/shared/validation/schemas";
 import { isValidationFailure, validateBody } from "@/shared/validation/helpers";
-import {
-  checkLoginGuard,
-  clearLoginAttempts,
-  recordLoginFailure,
-} from "@/server/auth/loginGuard";
+import { checkLoginGuard, clearLoginAttempts, recordLoginFailure } from "@/server/auth/loginGuard";
 
 // SECURITY: No hardcoded fallback — JWT_SECRET must be configured.
 if (!process.env.JWT_SECRET) {
diff --git a/src/app/api/providers/[id]/models/route.ts b/src/app/api/providers/[id]/models/route.ts
index 124c32ee4b..61dfe76020 100755
--- a/src/app/api/providers/[id]/models/route.ts
+++ b/src/app/api/providers/[id]/models/route.ts
@@ -65,7 +65,10 @@ import {
 
 type JsonRecord = Record<string, unknown>;
 
-const antigravityDiscoveryInflight = new Map<string, Promise<Array<{ id: string; name: string }>>>();
+const antigravityDiscoveryInflight = new Map<
+  string,
+  Promise<Array<{ id: string; name: string }>>
+>();
 
 function asRecord(value: unknown): JsonRecord {
   return value && typeof value === "object" && !Array.isArray(value) ? (value as JsonRecord) : {};
@@ -1636,7 +1639,11 @@ export async function GET(
         });
       }
 
-      const remoteModels = await fetchAntigravityDiscoveryModelsCached(accessToken, connectionId, proxy);
+      const remoteModels = await fetchAntigravityDiscoveryModelsCached(
+        accessToken,
+        connectionId,
+        proxy
+      );
       if (remoteModels.length > 0) {
         return buildApiDiscoveryResponse(remoteModels);
       }
diff --git a/src/app/api/settings/compression/route.ts b/src/app/api/settings/compression/route.ts
new file mode 100644
index 0000000000..7bc9ead411
--- /dev/null
+++ b/src/app/api/settings/compression/route.ts
@@ -0,0 +1,58 @@
+import { NextRequest, NextResponse } from "next/server";
+import { z } from "zod";
+import { isAuthenticated } from "@/shared/utils/apiAuth";
+import { isValidationFailure, validateBody } from "@/shared/validation/helpers";
+import { getCompressionSettings, updateCompressionSettings } from "@/lib/db/compression";
+
+const compressionModeSchema = z.enum(["off", "lite", "standard", "aggressive", "ultra"]);
+
+const compressionSettingsUpdateSchema = z
+  .object({
+    enabled: z.boolean().optional(),
+    defaultMode: compressionModeSchema.optional(),
+    autoTriggerTokens: z.number().int().min(0).optional(),
+    cacheMinutes: z.number().int().min(1).max(60).optional(),
+    preserveSystemPrompt: z.boolean().optional(),
+    comboOverrides: z.record(z.string(), compressionModeSchema).optional(),
+  })
+  .strict();
+
+export async function GET(request: NextRequest) {
+  if (!(await isAuthenticated(request))) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  try {
+    const settings = await getCompressionSettings();
+    return NextResponse.json(settings);
+  } catch (error) {
+    return NextResponse.json({ error: String(error) }, { status: 500 });
+  }
+}
+
+export async function PUT(request: NextRequest) {
+  if (!(await isAuthenticated(request))) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  try {
+    let rawBody: unknown;
+    try {
+      rawBody = await request.json();
+    } catch {
+      return NextResponse.json({ error: "Invalid JSON body" }, { status: 400 });
+    }
+
+    const validation = validateBody(compressionSettingsUpdateSchema, rawBody);
+    if (isValidationFailure(validation)) {
+      return NextResponse.json({ error: validation.error }, { status: 400 });
+    }
+
+    const settings = await updateCompressionSettings(
+      validation.data as Parameters<typeof updateCompressionSettings>[0]
+    );
+    return NextResponse.json(settings);
+  } catch (error) {
+    return NextResponse.json({ error: String(error) }, { status: 500 });
+  }
+}
diff --git a/src/app/api/usage/analytics/route.ts b/src/app/api/usage/analytics/route.ts
index 1d14c1e14d..2057c7bf43 100644
--- a/src/app/api/usage/analytics/route.ts
+++ b/src/app/api/usage/analytics/route.ts
@@ -140,10 +140,15 @@ export async function GET(request: Request) {
     // ── Enrich entries with missing apiKeyName ──────────────────────────
     try {
       // Only run enrichment if there are actually NULL entries
-      const hasNull = db.prepare("SELECT 1 FROM usage_history WHERE (api_key_name IS NULL OR api_key_name = '') AND connection_id IS NOT NULL LIMIT 1").get();
+      const hasNull = db
+        .prepare(
+          "SELECT 1 FROM usage_history WHERE (api_key_name IS NULL OR api_key_name = '') AND connection_id IS NOT NULL LIMIT 1"
+        )
+        .get();
       if (hasNull) {
         // Step 1: dominant key per connectionId from existing usage data
-        db.prepare(`
+        db.prepare(
+          `
           UPDATE usage_history
           SET 
             api_key_name = (
@@ -171,22 +176,29 @@ export async function GET(request: Request) {
                 WHERE uh3.connection_id = usage_history.connection_id
                   AND uh3.api_key_name IS NOT NULL AND uh3.api_key_name != ''
             )
-        `).run();
+        `
+        ).run();
 
         // Step 2 & 3: For still unresolved connections, check apiKeys config
-        const stillNull = db.prepare("SELECT DISTINCT connection_id FROM usage_history WHERE (api_key_name IS NULL OR api_key_name = '') AND connection_id IS NOT NULL").all();
+        const stillNull = db
+          .prepare(
+            "SELECT DISTINCT connection_id FROM usage_history WHERE (api_key_name IS NULL OR api_key_name = '') AND connection_id IS NOT NULL"
+          )
+          .all();
         if (stillNull.length > 0) {
           const { getApiKeys } = await import("@/lib/localDb");
           const apiKeys = (await getApiKeys()) as any[];
-          
-          const updateStmt = db.prepare("UPDATE usage_history SET api_key_name = ?, api_key_id = ? WHERE connection_id = ? AND (api_key_name IS NULL OR api_key_name = '')");
+
+          const updateStmt = db.prepare(
+            "UPDATE usage_history SET api_key_name = ?, api_key_id = ? WHERE connection_id = ? AND (api_key_name IS NULL OR api_key_name = '')"
+          );
           const updateMany = db.transaction((updates: any[]) => {
             for (const u of updates) updateStmt.run(u.name, u.id, u.cid);
           });
-          
+
           const updates = [];
           const orphanIds = new Set(stillNull.map((r: any) => r.connection_id));
-          
+
           for (const ak of apiKeys) {
             const allowed = Array.isArray(ak.allowedConnections) ? ak.allowedConnections : [];
             const keyName = ak.name || ak.id;
@@ -198,17 +210,23 @@ export async function GET(request: Request) {
               }
             }
           }
-          
+
           if (orphanIds.size > 0) {
             const unrestrictedKeys = apiKeys.filter(
-              (ak: any) => !Array.isArray(ak.allowedConnections) || ak.allowedConnections.length === 0
+              (ak: any) =>
+                !Array.isArray(ak.allowedConnections) || ak.allowedConnections.length === 0
             );
             if (unrestrictedKeys.length > 0) {
               let bestKey = unrestrictedKeys[0];
               let bestCount = -1;
               for (const uk of unrestrictedKeys) {
-                const countRow = db.prepare("SELECT COUNT(*) as c FROM usage_history WHERE api_key_name = ?").get(uk.name || uk.id) as any;
-                if (countRow.c > bestCount) { bestCount = countRow.c; bestKey = uk; }
+                const countRow = db
+                  .prepare("SELECT COUNT(*) as c FROM usage_history WHERE api_key_name = ?")
+                  .get(uk.name || uk.id) as any;
+                if (countRow.c > bestCount) {
+                  bestCount = countRow.c;
+                  bestKey = uk;
+                }
               }
               const fallbackName = bestKey.name || bestKey.id;
               const fallbackId = bestKey.id || null;
@@ -217,11 +235,11 @@ export async function GET(request: Request) {
               }
             }
           }
-          
+
           if (updates.length > 0) updateMany(updates);
         }
       }
-    } catch(e) {
+    } catch (e) {
       console.error("Failed to backfill missing api_key_name:", e);
     }
 
@@ -322,13 +340,15 @@ export async function GET(request: Request) {
         heatmapStart.setTime(customStart.getTime());
       }
     }
-    
+
     // Heatmap needs its own whereClause if api keys are filtered
     const heatmapConditions = ["timestamp >= @heatmapStart"];
     if (apiKeyWhere) heatmapConditions.push(apiKeyWhere);
     const heatmapParams: Record<string, string> = { heatmapStart: heatmapStart.toISOString() };
     if (apiKeyIds.length > 0) {
-      apiKeyIds.forEach((key, i) => { heatmapParams[`apiKey${i}`] = key; });
+      apiKeyIds.forEach((key, i) => {
+        heatmapParams[`apiKey${i}`] = key;
+      });
     }
 
     const heatmapRows = db
@@ -535,7 +555,7 @@ export async function GET(request: Request) {
             )
           : 0,
       avgLatencyMs: Math.round(Number(summaryRow?.avgLatencyMs || 0)),
-      totalCost: 0, 
+      totalCost: 0,
       firstRequest: summaryRow?.firstRequest || "",
       lastRequest: summaryRow?.lastRequest || "",
       fallbackCount: Number(fallbackRow?.fallbacks || 0),
@@ -772,10 +792,17 @@ export async function GET(request: Request) {
         const presetSinceIso = getRangeStartIso(presetRange);
         const presetConditions = [];
         const presetParams: Record<string, string> = {};
-        if (presetSinceIso) { presetConditions.push("timestamp >= @presetSince"); presetParams.presetSince = presetSinceIso; }
-        if (apiKeyWhere) { presetConditions.push(apiKeyWhere); Object.assign(presetParams, params); }
+        if (presetSinceIso) {
+          presetConditions.push("timestamp >= @presetSince");
+          presetParams.presetSince = presetSinceIso;
+        }
+        if (apiKeyWhere) {
+          presetConditions.push(apiKeyWhere);
+          Object.assign(presetParams, params);
+        }
 
-        const presetWhere = presetConditions.length > 0 ? `WHERE ${presetConditions.join(" AND ")}` : "";
+        const presetWhere =
+          presetConditions.length > 0 ? `WHERE ${presetConditions.join(" AND ")}` : "";
 
         const presetModelRows = db
           .prepare(
diff --git a/src/lib/db/compression.ts b/src/lib/db/compression.ts
new file mode 100644
index 0000000000..facaab214a
--- /dev/null
+++ b/src/lib/db/compression.ts
@@ -0,0 +1,50 @@
+import { getDbInstance } from "./core";
+import { backupDbFile } from "./backup";
+
+const DEFAULT_COMPRESSION_CONFIG = {
+  enabled: false,
+  defaultMode: "off" as const,
+  autoTriggerTokens: 0,
+  cacheMinutes: 5,
+  preserveSystemPrompt: true,
+  comboOverrides: {},
+};
+
+type CompressionConfig = typeof DEFAULT_COMPRESSION_CONFIG & {
+  comboOverrides: Record<string, "off" | "lite" | "standard" | "aggressive" | "ultra">;
+};
+
+export async function getCompressionSettings(): Promise<CompressionConfig> {
+  const db = getDbInstance();
+  const rows = db.prepare("SELECT key, value FROM key_value WHERE namespace = 'compression'").all();
+  const settings: Record<string, unknown> = { ...DEFAULT_COMPRESSION_CONFIG };
+  for (const row of rows) {
+    const record = row as Record<string, unknown>;
+    const key = typeof record.key === "string" ? record.key : null;
+    const rawValue = typeof record.value === "string" ? record.value : null;
+    if (!key || rawValue === null) continue;
+    try {
+      settings[key] = JSON.parse(rawValue);
+    } catch {
+      // skip malformed JSON
+    }
+  }
+  return settings as CompressionConfig;
+}
+
+export async function updateCompressionSettings(
+  updates: Partial<CompressionConfig>
+): Promise<CompressionConfig> {
+  const db = getDbInstance();
+  const insert = db.prepare(
+    "INSERT OR REPLACE INTO key_value (namespace, key, value) VALUES ('compression', ?, ?)"
+  );
+  const tx = db.transaction(() => {
+    for (const [key, value] of Object.entries(updates)) {
+      insert.run(key, JSON.stringify(value));
+    }
+  });
+  tx();
+  backupDbFile("pre-write");
+  return getCompressionSettings();
+}
diff --git a/src/lib/db/migrations/034_compression_settings.sql b/src/lib/db/migrations/034_compression_settings.sql
new file mode 100644
index 0000000000..1a63062c32
--- /dev/null
+++ b/src/lib/db/migrations/034_compression_settings.sql
@@ -0,0 +1,10 @@
+-- 034_compression_settings.sql
+-- Insert default compression settings into key_value table (namespace='compression')
+-- Uses INSERT OR IGNORE so existing user settings are never overwritten by migration replay.
+
+INSERT OR IGNORE INTO key_value (namespace, key, value) VALUES ('compression', 'enabled', 'false');
+INSERT OR IGNORE INTO key_value (namespace, key, value) VALUES ('compression', 'defaultMode', '"off"');
+INSERT OR IGNORE INTO key_value (namespace, key, value) VALUES ('compression', 'autoTriggerTokens', '0');
+INSERT OR IGNORE INTO key_value (namespace, key, value) VALUES ('compression', 'cacheMinutes', '5');
+INSERT OR IGNORE INTO key_value (namespace, key, value) VALUES ('compression', 'preserveSystemPrompt', 'true');
+INSERT OR IGNORE INTO key_value (namespace, key, value) VALUES ('compression', 'comboOverrides', '{}');
diff --git a/tests/integration/compression-pipeline.test.ts b/tests/integration/compression-pipeline.test.ts
new file mode 100644
index 0000000000..99b4702458
--- /dev/null
+++ b/tests/integration/compression-pipeline.test.ts
@@ -0,0 +1,120 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import {
+  selectCompressionStrategy,
+  getEffectiveMode,
+  applyCompression,
+} from "../../open-sse/services/compression/strategySelector.ts";
+import { applyLiteCompression } from "../../open-sse/services/compression/lite.ts";
+import {
+  createCompressionStats,
+  estimateCompressionTokens,
+} from "../../open-sse/services/compression/stats.ts";
+import type { CompressionConfig } from "../../open-sse/services/compression/types.ts";
+
+const baseConfig: CompressionConfig = {
+  enabled: true,
+  defaultMode: "lite",
+  autoTriggerTokens: 0,
+  cacheMinutes: 5,
+  preserveSystemPrompt: true,
+  comboOverrides: {},
+};
+
+describe("Full Compression Pipeline", () => {
+  it("end-to-end: lite mode compresses whitespace and tracks stats", () => {
+    const body = {
+      messages: [
+        { role: "system", content: "You are helpful." },
+        { role: "system", content: "You are helpful." },
+        { role: "user", content: "hello\n\n\n\nworld" },
+      ],
+    };
+
+    // Step 1: Select strategy
+    const mode = selectCompressionStrategy(baseConfig, null, 100);
+    assert.equal(mode, "lite");
+
+    // Step 2: Apply compression
+    const result = applyCompression(body, mode);
+    assert.equal(result.compressed, true);
+    assert.ok(result.stats);
+
+    // Step 3: Verify stats
+    assert.ok(result.stats!.originalTokens > 0);
+    assert.ok(result.stats!.compressedTokens > 0);
+    assert.ok(result.stats!.compressedTokens <= result.stats!.originalTokens);
+    assert.ok(result.stats!.savingsPercent >= 0);
+    assert.equal(result.stats!.mode, "lite");
+  });
+
+  it("end-to-end: off mode returns unchanged body", () => {
+    const body = { messages: [{ role: "user", content: "test" }] };
+    const offConfig = { ...baseConfig, enabled: false };
+    const mode = selectCompressionStrategy(offConfig, null, 100);
+    assert.equal(mode, "off");
+
+    const result = applyCompression(body, mode);
+    assert.equal(result.compressed, false);
+    assert.equal(result.stats, null);
+  });
+
+  it("end-to-end: combo override selects lite for specific combo", () => {
+    const config: CompressionConfig = {
+      ...baseConfig,
+      defaultMode: "off" as const,
+      comboOverrides: { "my-combo": "lite" as const },
+    };
+    const body = { messages: [{ role: "user", content: "test\n\n\n\nmessage" }] };
+
+    const mode = selectCompressionStrategy(config, "my-combo", 100);
+    assert.equal(mode, "lite");
+
+    const result = applyCompression(body, mode);
+    assert.equal(result.compressed, true);
+  });
+
+  it("end-to-end: auto-trigger activates compression", () => {
+    const config: CompressionConfig = {
+      ...baseConfig,
+      defaultMode: "off" as const,
+      autoTriggerTokens: 50,
+    };
+    const body = { messages: [{ role: "user", content: "x".repeat(1000) }] };
+
+    // Below threshold → off
+    const mode1 = getEffectiveMode(config, null, 10);
+    assert.equal(mode1, "off");
+
+    // Above threshold → lite
+    const mode2 = getEffectiveMode(config, null, 100);
+    assert.equal(mode2, "lite");
+  });
+
+  it("lite compression + stats pipeline works together", () => {
+    const body = {
+      messages: [
+        { role: "system", content: "Be helpful." },
+        { role: "system", content: "Be helpful." },
+        { role: "user", content: "hello\n\n\n\nworld" },
+        { role: "user", content: "hello\n\n\n\nworld" },
+      ],
+    };
+
+    const result = applyLiteCompression(body);
+    assert.equal(result.compressed, true);
+    assert.ok(result.stats);
+    assert.ok(result.stats.savingsPercent > 0);
+    assert.ok(result.stats.techniquesUsed.length >= 1);
+  });
+
+  it("token estimation is consistent", () => {
+    const text = "hello world this is a test";
+    const tokens = estimateCompressionTokens(text);
+    assert.equal(tokens, Math.ceil(text.length / 4));
+
+    const obj = { messages: [{ role: "user", content: text }] };
+    const objTokens = estimateCompressionTokens(obj);
+    assert.equal(objTokens, Math.ceil(JSON.stringify(obj).length / 4));
+  });
+});
diff --git a/tests/unit/cli-tools.test.ts b/tests/unit/cli-tools.test.ts
index 171a0d2b46..fadd60e8a0 100644
--- a/tests/unit/cli-tools.test.ts
+++ b/tests/unit/cli-tools.test.ts
@@ -8,12 +8,10 @@ const {
   CLI_COMPAT_TOGGLE_IDS,
   IMPLEMENTED_CLI_FINGERPRINT_PROVIDER_IDS,
   normalizeCliCompatProviderId,
-} =
-  await import("../../src/shared/constants/cliCompatProviders.ts");
+} = await import("../../src/shared/constants/cliCompatProviders.ts");
 const { CLI_TOOL_IDS } = await import("../../src/shared/services/cliRuntime.ts");
-const { applyFingerprint, isCliCompatEnabled, setCliCompatProviders } = await import(
-  "../../open-sse/config/cliFingerprints.ts"
-);
+const { applyFingerprint, isCliCompatEnabled, setCliCompatProviders } =
+  await import("../../open-sse/config/cliFingerprints.ts");
 
 test("Amp CLI is registered as a guide-based CLI tool with shorthand mapping guidance", () => {
   const amp = CLI_TOOLS.amp;
diff --git a/tests/unit/combo-stream-readiness-fallback.test.ts b/tests/unit/combo-stream-readiness-fallback.test.ts
index ed8cdc1e28..7f1122a24e 100644
--- a/tests/unit/combo-stream-readiness-fallback.test.ts
+++ b/tests/unit/combo-stream-readiness-fallback.test.ts
@@ -71,10 +71,10 @@ async function applyStreamReadiness(response: Response): Promise<Response> {
 }
 
 function errorResponse(status: number, message: string): Response {
-  return new Response(
-    JSON.stringify({ error: { message, type: "upstream_error" } }),
-    { status, headers: { "Content-Type": "application/json" } }
-  );
+  return new Response(JSON.stringify({ error: { message, type: "upstream_error" } }), {
+    status,
+    headers: { "Content-Type": "application/json" },
+  });
 }
 
 test("combo falls back when first model returns HTTP 200 zombie SSE stream", async () => {
@@ -113,10 +113,7 @@ test("combo falls back when first model returns HTTP 200 zombie SSE stream", asy
   assert.deepEqual(calls, ["glm/zombie-model", "openai/gpt-5.4-mini"]);
   assert.ok(
     log.entries.some(
-      (e) =>
-        e.level === "warn" &&
-        e.tag === "COMBO" &&
-        String(e.msg).includes("glm/zombie-model")
+      (e) => e.level === "warn" && e.tag === "COMBO" && String(e.msg).includes("glm/zombie-model")
     ),
     "combo should log warning for the failed model"
   );
@@ -190,11 +187,7 @@ test("combo retries 504 on same model before falling through (transient retry)",
 
   assert.equal(result.ok, true, "combo should succeed via fallback after retries");
   const zombieCalls = calls.filter((c) => c === "glm/zombie");
-  assert.equal(
-    zombieCalls.length,
-    2,
-    "combo should retry zombie once before falling through"
-  );
+  assert.equal(zombieCalls.length, 2, "combo should retry zombie once before falling through");
   assert.ok(calls.includes("openai/gpt-5.4-mini"), "combo should reach fallback model");
 });
 
diff --git a/tests/unit/compression/db.test.ts b/tests/unit/compression/db.test.ts
new file mode 100644
index 0000000000..4d78a929c3
--- /dev/null
+++ b/tests/unit/compression/db.test.ts
@@ -0,0 +1,113 @@
+import { describe, it, beforeEach, afterEach, after } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-compression-db-"));
+const ORIGINAL_DATA_DIR = process.env.DATA_DIR;
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../../src/lib/db/core.ts");
+const { getCompressionSettings, updateCompressionSettings } =
+  await import("../../../src/lib/db/compression.ts");
+
+beforeEach(() => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+});
+
+afterEach(() => {
+  core.resetDbInstance();
+});
+
+after(() => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  if (ORIGINAL_DATA_DIR === undefined) {
+    delete process.env.DATA_DIR;
+  } else {
+    process.env.DATA_DIR = ORIGINAL_DATA_DIR;
+  }
+});
+
+describe("getCompressionSettings", () => {
+  it("returns default settings structure", async () => {
+    const settings = await getCompressionSettings();
+    assert.equal(typeof settings.enabled, "boolean");
+    assert.equal(typeof settings.defaultMode, "string");
+    assert.equal(typeof settings.autoTriggerTokens, "number");
+    assert.equal(typeof settings.cacheMinutes, "number");
+    assert.equal(typeof settings.preserveSystemPrompt, "boolean");
+    assert.equal(typeof settings.comboOverrides, "object");
+  });
+
+  it("has correct default values", async () => {
+    const settings = await getCompressionSettings();
+    assert.equal(settings.enabled, false);
+    assert.equal(settings.defaultMode, "off");
+    assert.equal(settings.autoTriggerTokens, 0);
+    assert.equal(settings.cacheMinutes, 5);
+    assert.equal(settings.preserveSystemPrompt, true);
+    assert.deepEqual(settings.comboOverrides, {});
+  });
+});
+
+describe("updateCompressionSettings", () => {
+  it("updates enabled flag", async () => {
+    await updateCompressionSettings({ enabled: true } as any);
+    const settings = await getCompressionSettings();
+    assert.equal(settings.enabled, true);
+    // Reset
+    await updateCompressionSettings({ enabled: false } as any);
+  });
+
+  it("updates defaultMode", async () => {
+    await updateCompressionSettings({ defaultMode: "lite" } as any);
+    const settings = await getCompressionSettings();
+    assert.equal(settings.defaultMode, "lite");
+    // Reset
+    await updateCompressionSettings({ defaultMode: "off" } as any);
+  });
+
+  it("updates autoTriggerTokens", async () => {
+    await updateCompressionSettings({ autoTriggerTokens: 5000 } as any);
+    const settings = await getCompressionSettings();
+    assert.equal(settings.autoTriggerTokens, 5000);
+    // Reset
+    await updateCompressionSettings({ autoTriggerTokens: 0 } as any);
+  });
+
+  it("updates multiple settings at once", async () => {
+    await updateCompressionSettings({
+      enabled: true,
+      defaultMode: "lite",
+      autoTriggerTokens: 1000,
+      cacheMinutes: 10,
+    } as any);
+    const settings = await getCompressionSettings();
+    assert.equal(settings.enabled, true);
+    assert.equal(settings.defaultMode, "lite");
+    assert.equal(settings.autoTriggerTokens, 1000);
+    assert.equal(settings.cacheMinutes, 10);
+    // Reset all
+    await updateCompressionSettings({
+      enabled: false,
+      defaultMode: "off",
+      autoTriggerTokens: 0,
+      cacheMinutes: 5,
+    } as any);
+  });
+
+  it("preserves unmodified settings", async () => {
+    const before = await getCompressionSettings();
+    await updateCompressionSettings({ enabled: true } as any);
+    const after = await getCompressionSettings();
+    assert.equal(after.enabled, true);
+    assert.equal(after.defaultMode, before.defaultMode);
+    assert.equal(after.cacheMinutes, before.cacheMinutes);
+    // Reset
+    await updateCompressionSettings({ enabled: false } as any);
+  });
+});
diff --git a/tests/unit/compression/lite.test.ts b/tests/unit/compression/lite.test.ts
new file mode 100644
index 0000000000..c3119f2c5e
--- /dev/null
+++ b/tests/unit/compression/lite.test.ts
@@ -0,0 +1,209 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import {
+  applyLiteCompression,
+  collapseWhitespace,
+  dedupSystemPrompt,
+  compressToolResults,
+  removeRedundantContent,
+  replaceImageUrls,
+} from "../../../open-sse/services/compression/lite.ts";
+
+describe("collapseWhitespace", () => {
+  it("collapses 3+ newlines to 2", () => {
+    const body = { messages: [{ role: "user", content: "hello\n\n\n\nworld" }] };
+    const result = collapseWhitespace(body);
+    assert.equal(result.applied, true);
+    assert.equal(result.body.messages![0].content as string, "hello\n\nworld");
+  });
+
+  it("does not modify already-normal whitespace", () => {
+    const body = { messages: [{ role: "user", content: "hello\n\nworld" }] };
+    const result = collapseWhitespace(body);
+    assert.equal(result.applied, false);
+  });
+
+  it("trims trailing spaces", () => {
+    const body = { messages: [{ role: "user", content: "hello   " }] };
+    const result = collapseWhitespace(body);
+    assert.equal(result.applied, true);
+    assert.equal(result.body.messages![0].content as string, "hello");
+  });
+
+  it("returns unchanged when no messages", () => {
+    const body = {};
+    const result = collapseWhitespace(body);
+    assert.equal(result.applied, false);
+  });
+
+  it("skips non-string content", () => {
+    const body = { messages: [{ role: "user", content: [{ type: "text", text: "hello" }] }] };
+    const result = collapseWhitespace(body);
+    assert.equal(result.applied, false);
+  });
+});
+
+describe("dedupSystemPrompt", () => {
+  it("removes duplicate system prompts", () => {
+    const body = {
+      messages: [
+        { role: "system", content: "You are helpful." },
+        { role: "system", content: "You are helpful." },
+        { role: "user", content: "hi" },
+      ],
+    };
+    const result = dedupSystemPrompt(body);
+    assert.equal(result.applied, true);
+    assert.equal(result.body.messages!.length, 2);
+  });
+
+  it("keeps different system prompts", () => {
+    const body = {
+      messages: [
+        { role: "system", content: "You are helpful." },
+        { role: "system", content: "Be concise." },
+      ],
+    };
+    const result = dedupSystemPrompt(body);
+    assert.equal(result.applied, false);
+    assert.equal(result.body.messages!.length, 2);
+  });
+
+  it("returns unchanged when no messages", () => {
+    const result = dedupSystemPrompt({});
+    assert.equal(result.applied, false);
+  });
+});
+
+describe("compressToolResults", () => {
+  it("truncates long tool results", () => {
+    const longContent = "x".repeat(3000);
+    const body = { messages: [{ role: "tool", content: longContent }] };
+    const result = compressToolResults(body);
+    assert.equal(result.applied, true);
+    const content = result.body.messages![0].content as string;
+    assert.ok(content.length < 3000);
+    assert.ok(content.includes("[truncated]"));
+  });
+
+  it("keeps short tool results unchanged", () => {
+    const body = { messages: [{ role: "tool", content: "short result" }] };
+    const result = compressToolResults(body);
+    assert.equal(result.applied, false);
+  });
+
+  it("skips non-tool messages", () => {
+    const body = { messages: [{ role: "user", content: "x".repeat(3000) }] };
+    const result = compressToolResults(body);
+    assert.equal(result.applied, false);
+  });
+});
+
+describe("removeRedundantContent", () => {
+  it("removes consecutive duplicate messages", () => {
+    const body = {
+      messages: [
+        { role: "user", content: "hello" },
+        { role: "user", content: "hello" },
+      ],
+    };
+    const result = removeRedundantContent(body);
+    assert.equal(result.applied, true);
+    assert.equal(result.body.messages!.length, 1);
+  });
+
+  it("keeps non-duplicate messages", () => {
+    const body = {
+      messages: [
+        { role: "user", content: "hello" },
+        { role: "user", content: "world" },
+      ],
+    };
+    const result = removeRedundantContent(body);
+    assert.equal(result.applied, false);
+    assert.equal(result.body.messages!.length, 2);
+  });
+
+  it("only removes same-role consecutive duplicates", () => {
+    const body = {
+      messages: [
+        { role: "system", content: "hello" },
+        { role: "user", content: "hello" },
+      ],
+    };
+    const result = removeRedundantContent(body);
+    assert.equal(result.applied, false);
+  });
+});
+
+describe("replaceImageUrls", () => {
+  it("replaces base64 images for non-vision models", () => {
+    const body = {
+      messages: [
+        {
+          role: "user",
+          content: [{ type: "image_url", image_url: { url: "data:image/png;base64,iVBOR" } }],
+        },
+      ],
+    };
+    const result = replaceImageUrls(body, "gpt-3.5-turbo");
+    assert.equal(result.applied, true);
+    const content = result.body.messages![0].content as Array<Record<string, unknown>>;
+    assert.equal(content[0].type, "text");
+    assert.ok((content[0].text as string).includes("[image:"));
+  });
+
+  it("keeps images for vision models", () => {
+    const body = {
+      messages: [
+        {
+          role: "user",
+          content: [{ type: "image_url", image_url: { url: "data:image/png;base64,iVBOR" } }],
+        },
+      ],
+    };
+    const result = replaceImageUrls(body, "gpt-4o");
+    assert.equal(result.applied, false);
+  });
+
+  it("skips non-image content", () => {
+    const body = {
+      messages: [{ role: "user", content: "just text" }],
+    };
+    const result = replaceImageUrls(body, "gpt-3.5-turbo");
+    assert.equal(result.applied, false);
+  });
+});
+
+describe("applyLiteCompression", () => {
+  it("applies all techniques that match", () => {
+    const body = {
+      messages: [
+        { role: "system", content: "You are helpful." },
+        { role: "system", content: "You are helpful." },
+        { role: "user", content: "hello\n\n\n\nworld" },
+        { role: "user", content: "hello\n\n\n\nworld" },
+      ],
+    };
+    const result = applyLiteCompression(body);
+    assert.equal(result.compressed, true);
+    assert.ok(result.stats);
+    assert.ok(result.stats.techniquesUsed.length >= 2);
+    assert.ok(result.stats.savingsPercent > 0);
+  });
+
+  it("returns no compression for clean input", () => {
+    const body = {
+      messages: [{ role: "user", content: "clean message" }],
+    };
+    const result = applyLiteCompression(body);
+    assert.equal(result.compressed, false);
+    assert.equal(result.stats, null);
+  });
+
+  it("handles empty messages array", () => {
+    const body = { messages: [] };
+    const result = applyLiteCompression(body);
+    assert.equal(result.compressed, false);
+  });
+});
diff --git a/tests/unit/compression/stats.test.ts b/tests/unit/compression/stats.test.ts
new file mode 100644
index 0000000000..203e766af3
--- /dev/null
+++ b/tests/unit/compression/stats.test.ts
@@ -0,0 +1,92 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import {
+  estimateCompressionTokens,
+  createCompressionStats,
+  trackCompressionStats,
+} from "../../../open-sse/services/compression/stats.ts";
+
+describe("estimateCompressionTokens", () => {
+  it("returns 0 for null", () => {
+    assert.equal(estimateCompressionTokens(null), 0);
+  });
+
+  it("returns 0 for undefined", () => {
+    assert.equal(estimateCompressionTokens(undefined), 0);
+  });
+
+  it("returns 0 for empty string", () => {
+    assert.equal(estimateCompressionTokens(""), 0);
+  });
+
+  it("estimates tokens from text (chars/4)", () => {
+    assert.equal(estimateCompressionTokens("hello world"), 3);
+  });
+
+  it("estimates tokens from object", () => {
+    const tokens = estimateCompressionTokens({ messages: [{ role: "user", content: "test" }] });
+    assert.ok(tokens > 0);
+  });
+
+  it("handles long strings", () => {
+    const tokens = estimateCompressionTokens("x".repeat(400));
+    assert.equal(tokens, 100);
+  });
+});
+
+describe("createCompressionStats", () => {
+  it("calculates savings correctly", () => {
+    const original = { messages: [{ role: "user", content: "x".repeat(100) }] };
+    const compressed = { messages: [{ role: "user", content: "x".repeat(80) }] };
+    const origTokens = Math.ceil(JSON.stringify(original).length / 4);
+    const compTokens = Math.ceil(JSON.stringify(compressed).length / 4);
+    const expectedSavings = Math.round(((origTokens - compTokens) / origTokens) * 10000) / 100;
+    const stats = createCompressionStats(original, compressed, "lite", ["whitespace"]);
+    assert.equal(stats.originalTokens, origTokens);
+    assert.equal(stats.compressedTokens, compTokens);
+    assert.equal(stats.savingsPercent, expectedSavings);
+    assert.deepEqual(stats.techniquesUsed, ["whitespace"]);
+    assert.equal(stats.mode, "lite");
+    assert.ok(stats.timestamp > 0);
+  });
+
+  it("handles zero original tokens", () => {
+    const original = {};
+    const compressed = {};
+    const stats = createCompressionStats(original, compressed, "off", []);
+    assert.equal(stats.savingsPercent, 0);
+  });
+
+  it("rounds savings to 2 decimal places", () => {
+    const original = { messages: [{ role: "user", content: "x".repeat(97) }] };
+    const compressed = { messages: [{ role: "user", content: "x".repeat(80) }] };
+    const stats = createCompressionStats(original, compressed, "lite", ["test"]);
+    assert.ok(Number.isFinite(stats.savingsPercent));
+  });
+});
+
+describe("trackCompressionStats", () => {
+  it("does not throw for zero tokens", () => {
+    const stats = {
+      originalTokens: 0,
+      compressedTokens: 0,
+      savingsPercent: 0,
+      techniquesUsed: [],
+      mode: "off" as const,
+      timestamp: Date.now(),
+    };
+    assert.doesNotThrow(() => trackCompressionStats(stats));
+  });
+
+  it("logs compression stats", () => {
+    const stats = {
+      originalTokens: 100,
+      compressedTokens: 80,
+      savingsPercent: 20,
+      techniquesUsed: ["whitespace"],
+      mode: "lite" as const,
+      timestamp: Date.now(),
+    };
+    assert.doesNotThrow(() => trackCompressionStats(stats));
+  });
+});
diff --git a/tests/unit/compression/strategySelector.test.ts b/tests/unit/compression/strategySelector.test.ts
new file mode 100644
index 0000000000..510d27f827
--- /dev/null
+++ b/tests/unit/compression/strategySelector.test.ts
@@ -0,0 +1,125 @@
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+import {
+  selectCompressionStrategy,
+  getEffectiveMode,
+  applyCompression,
+  checkComboOverride,
+  shouldAutoTrigger,
+} from "../../../open-sse/services/compression/strategySelector.ts";
+import type { CompressionConfig } from "../../../open-sse/services/compression/types.ts";
+
+const baseConfig: CompressionConfig = {
+  enabled: true,
+  defaultMode: "lite",
+  autoTriggerTokens: 0,
+  cacheMinutes: 5,
+  preserveSystemPrompt: true,
+  comboOverrides: {},
+};
+
+describe("checkComboOverride", () => {
+  it("returns null when comboId is null", () => {
+    assert.equal(checkComboOverride(baseConfig, null), null);
+  });
+
+  it("returns null when comboOverrides is empty", () => {
+    assert.equal(checkComboOverride(baseConfig, "my-combo"), null);
+  });
+
+  it("returns mode when combo override exists", () => {
+    const config = { ...baseConfig, comboOverrides: { "my-combo": "off" as const } };
+    assert.equal(checkComboOverride(config, "my-combo"), "off");
+  });
+
+  it("returns null for non-existent combo", () => {
+    const config = { ...baseConfig, comboOverrides: { "other-combo": "lite" as const } };
+    assert.equal(checkComboOverride(config, "my-combo"), null);
+  });
+});
+
+describe("shouldAutoTrigger", () => {
+  it("returns false when autoTriggerTokens is 0", () => {
+    assert.equal(shouldAutoTrigger(baseConfig, 5000), false);
+  });
+
+  it("returns false when tokens below threshold", () => {
+    const config = { ...baseConfig, autoTriggerTokens: 1000 };
+    assert.equal(shouldAutoTrigger(config, 500), false);
+  });
+
+  it("returns true when tokens at threshold", () => {
+    const config = { ...baseConfig, autoTriggerTokens: 1000 };
+    assert.equal(shouldAutoTrigger(config, 1000), true);
+  });
+
+  it("returns true when tokens above threshold", () => {
+    const config = { ...baseConfig, autoTriggerTokens: 1000 };
+    assert.equal(shouldAutoTrigger(config, 1500), true);
+  });
+});
+
+describe("getEffectiveMode", () => {
+  it("returns off when not enabled", () => {
+    const config = { ...baseConfig, enabled: false };
+    assert.equal(getEffectiveMode(config, null, 100), "off");
+  });
+
+  it("returns default mode when no overrides", () => {
+    assert.equal(getEffectiveMode(baseConfig, null, 100), "lite");
+  });
+
+  it("returns combo override mode when present", () => {
+    const config = {
+      ...baseConfig,
+      defaultMode: "off" as const,
+      comboOverrides: { "my-combo": "lite" as const },
+    };
+    assert.equal(getEffectiveMode(config, "my-combo", 100), "lite");
+  });
+
+  it("returns lite when auto-trigger threshold reached", () => {
+    const config = { ...baseConfig, defaultMode: "off" as const, autoTriggerTokens: 1000 };
+    assert.equal(getEffectiveMode(config, null, 1500), "lite");
+  });
+
+  it("combo override takes precedence over auto-trigger", () => {
+    const config = {
+      ...baseConfig,
+      defaultMode: "off" as const,
+      autoTriggerTokens: 100,
+      comboOverrides: { "my-combo": "off" as const },
+    };
+    assert.equal(getEffectiveMode(config, "my-combo", 500), "off");
+  });
+});
+
+describe("selectCompressionStrategy", () => {
+  it("returns effective mode", () => {
+    assert.equal(selectCompressionStrategy(baseConfig, null, 100), "lite");
+  });
+});
+
+describe("applyCompression", () => {
+  it("returns unchanged body for off mode", () => {
+    const body = { messages: [{ role: "user", content: "test" }] };
+    const result = applyCompression(body, "off");
+    assert.equal(result.compressed, false);
+    assert.equal(result.stats, null);
+    assert.deepEqual(result.body, body);
+  });
+
+  it("applies lite compression for lite mode", () => {
+    const body = { messages: [{ role: "user", content: "test\n\n\n\nmessage" }] };
+    const result = applyCompression(body, "lite");
+    assert.equal(result.compressed, true);
+    assert.ok(result.stats);
+    assert.equal(result.stats.mode, "lite");
+  });
+
+  it("returns unchanged body for standard mode (Phase 2)", () => {
+    const body = { messages: [{ role: "user", content: "test" }] };
+    const result = applyCompression(body, "standard");
+    assert.equal(result.compressed, false);
+  });
+});
diff --git a/tests/unit/provider-header-profiles.test.ts b/tests/unit/provider-header-profiles.test.ts
index 4383d5a262..df7e79b340 100644
--- a/tests/unit/provider-header-profiles.test.ts
+++ b/tests/unit/provider-header-profiles.test.ts
@@ -48,7 +48,10 @@ test("provider header profiles expose dedicated refresh, qwen, qoder, kiro and c
 
   const qwenHeaders = getQwenOauthHeaders();
   assert.equal(qwenHeaders["User-Agent"], getQwenCliUserAgent());
-  assert.equal(qwenHeaders["User-Agent"], `QwenCode/${QWEN_CLI_VERSION} (${process.platform}; ${process.arch})`);
+  assert.equal(
+    qwenHeaders["User-Agent"],
+    `QwenCode/${QWEN_CLI_VERSION} (${process.platform}; ${process.arch})`
+  );
   assert.notEqual(qwenHeaders["User-Agent"], "QwenCode/0.15.3 (linux; x64)");
   assert.equal(qwenHeaders["X-Dashscope-UserAgent"], getQwenCliUserAgent());
   assert.equal(qwenHeaders["X-Stainless-Package-Version"], "5.11.0");
diff --git a/tests/unit/stream-readiness.test.ts b/tests/unit/stream-readiness.test.ts
index 2e429921d9..a86c37dd31 100644
--- a/tests/unit/stream-readiness.test.ts
+++ b/tests/unit/stream-readiness.test.ts
@@ -100,7 +100,10 @@ test("ensureStreamReadiness preserves buffered chunks when stream starts", async
 
 test("ensureStreamReadiness returns 504 when no useful content arrives before timeout", async () => {
   const response = new Response(
-    streamFromChunks([": keepalive\n\n", `data: ${JSON.stringify({ type: "response.created" })}\n\n`], 20),
+    streamFromChunks(
+      [": keepalive\n\n", `data: ${JSON.stringify({ type: "response.created" })}\n\n`],
+      20
+    ),
     { status: 200, headers: { "Content-Type": "text/event-stream" } }
   );
 
diff --git a/tests/unit/usage-service-hardening.test.ts b/tests/unit/usage-service-hardening.test.ts
index bf17bb6546..7253465568 100644
--- a/tests/unit/usage-service-hardening.test.ts
+++ b/tests/unit/usage-service-hardening.test.ts
@@ -421,7 +421,9 @@ test("usage service manual Antigravity refresh bypasses usage TTL caches", async
   globalThis.fetch = async (url) => {
     const urlStr = String(url);
     if (urlStr.includes("loadCodeAssist")) {
-      return new Response(JSON.stringify({ cloudaicompanionProject: "ag-project" }), { status: 200 });
+      return new Response(JSON.stringify({ cloudaicompanionProject: "ag-project" }), {
+        status: 200,
+      });
     }
 
     if (urlStr.includes("streamGenerateContent")) {