From 9be87dd8a976953b2e4de758fd22f2a1d05b0340 Mon Sep 17 00:00:00 2001
From: Sam Rolfe <samuelrolfe@gmail.com>
Date: Wed, 10 Jun 2026 14:55:33 +1000
Subject: [PATCH] =?UTF-8?q?feat:=20integrate=20Headroom=20compression=20-?=
 =?UTF-8?q?=20compress=20large=20analysis/code/devops=20contexts=20(?=
 =?UTF-8?q?=E2=89=A55K=20tokens)=20via=20context=20event?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 extensions/smart-router/index.ts          | 48 +++++++++++++++++++++++
 extensions/smart-router/package-lock.json | 45 +++++++++++++++++++++
 extensions/smart-router/package.json      | 16 ++++++++
 3 files changed, 109 insertions(+)
 create mode 100644 extensions/smart-router/package-lock.json
 create mode 100644 extensions/smart-router/package.json

diff --git a/extensions/smart-router/index.ts b/extensions/smart-router/index.ts
index 1df2574..0cd5cd4 100644
--- a/extensions/smart-router/index.ts
+++ b/extensions/smart-router/index.ts
@@ -5,11 +5,30 @@ import type {
   BeforeAgentStartEventResult,
   ExtensionCommandContext,
 } from "@earendil-works/pi-coding-agent";
+import { compress } from "headroom-ai";
 
 // Global state for manual model lock
 let isLocked = false;
 let lockedModel: any = null;
 
+// Tags that trigger Headroom context compression.
+// read / discuss / search skip compression entirely.
+const COMPRESS_TAGS = new Set([
+  "devops-low",
+  "devops-high",
+  "code-analysis-low",
+  "code-analysis-high",
+  "codewrite-low",
+  "codewrite-high",
+]);
+
+// Minimum message size (in chars) before compression activates.
+// ~5K tokens ≈ 20K characters (rough 4:1 ratio).
+const COMPRESS_MIN_CHARS = 20_000;
+
+// Current routing tag for the active turn (used by context handler)
+let currentTag: string | null = null;
+
 // Model ID mappings for routing
 const MODELS: Record<string, { provider: string; id: string }> = {
   "free-core":          { provider: "openrouter", id: "free" },
@@ -193,6 +212,9 @@ export default function (pi: ExtensionAPI) {
         pi.setThinkingLevel(thinkingLevel as any);
       }
 
+      // Store tag for compression check in context event
+      currentTag = tag;
+
       // Show routing decision in status bar
       ctx.ui.setStatus("router", `🎯 ${tag} → ${modelLabel(modelKey)}`);
 
@@ -203,4 +225,30 @@ export default function (pi: ExtensionAPI) {
       ctx.ui.setStatus("router", `⚠️ fallback ${modelLabel("free-core")}`);
     }
   });
+
+  // 4. Compress large contexts before LLM turns (Headroom)
+  pi.on("context", async (event, ctx) => {
+    // Only compress for analysis/coding/devops tags
+    if (!currentTag || !COMPRESS_TAGS.has(currentTag)) return;
+
+    // Quick size check before calling the proxy
+    const totalChars = JSON.stringify(event.messages).length;
+    if (totalChars < COMPRESS_MIN_CHARS) return;
+
+    try {
+      const result = await compress(event.messages, {
+        baseUrl: "http://localhost:8787",
+        fallback: true,
+        timeout: 15_000,
+      });
+      if (result.messages && result.messages.length > 0) {
+        const saved = ((result.tokensBefore - result.tokensAfter) / result.tokensBefore * 100).toFixed(0);
+        ctx.ui.setStatus("compression", `📦 ${saved}%`);
+        return { messages: result.messages };
+      }
+    } catch {
+      // Proxy down — pass through (fallback: true already handles transport errors)
+      ctx.ui.setStatus("compression", "⚠️ offline");
+    }
+  });
 }
diff --git a/extensions/smart-router/package-lock.json b/extensions/smart-router/package-lock.json
new file mode 100644
index 0000000..cfb45a5
--- /dev/null
+++ b/extensions/smart-router/package-lock.json
@@ -0,0 +1,45 @@
+{
+  "name": "smart-router",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "smart-router",
+      "version": "1.0.0",
+      "license": "ISC",
+      "dependencies": {
+        "headroom-ai": "^0.22.4"
+      }
+    },
+    "node_modules/headroom-ai": {
+      "version": "0.22.4",
+      "resolved": "https://registry.npmjs.org/headroom-ai/-/headroom-ai-0.22.4.tgz",
+      "integrity": "sha512-9a0rgB/jsWe8gs/ggyUwe6E8DYwKAuBvlUml2ApwlUjb5EfJ611X6X+WG0SiXw3nO6sdyV1/+Ah5uw9P7ecnjw==",
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=18.0.0"
+      },
+      "peerDependencies": {
+        "@ai-sdk/provider": ">=1.0.0",
+        "@anthropic-ai/sdk": ">=0.30.0",
+        "ai": ">=6.0.0",
+        "openai": ">=4.0.0"
+      },
+      "peerDependenciesMeta": {
+        "@ai-sdk/provider": {
+          "optional": true
+        },
+        "@anthropic-ai/sdk": {
+          "optional": true
+        },
+        "ai": {
+          "optional": true
+        },
+        "openai": {
+          "optional": true
+        }
+      }
+    }
+  }
+}
diff --git a/extensions/smart-router/package.json b/extensions/smart-router/package.json
new file mode 100644
index 0000000..40d4c4d
--- /dev/null
+++ b/extensions/smart-router/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "smart-router",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "type": "commonjs",
+  "dependencies": {
+    "headroom-ai": "^0.22.4"
+  }
+}