feat(shared): add compression field to attach/attached protocol types

Add optional compression?: 'deflate' to AttachRequest and AttachedEvent interfaces. Add string type validation for the compression field in codec validateFields() for both attach and attached message types. Includes 8 new codec tests for round-trip and validation.

Author: rbonestell

src/__tests__/codec.test.ts

@@ -74,6 +74,24 @@ describe('HostRequest round-trip', () => {
     expect(result).toEqual(msg);
   });
 
+  it('encodes/decodes attach with compression', () => {
+    const msg: HostRequest = { type: 'attach', paneId: '%1', cols: 80, rows: 24, compression: 'deflate' };
+    const result = roundTrip(msg);
+    expect(result).toEqual(msg);
+    if (result.type === 'attach') {
+      expect(result.compression).toBe('deflate');
+    }
+  });
+
+  it('encodes/decodes attach without compression (field absent)', () => {
+    const msg: HostRequest = { type: 'attach', paneId: '%1', cols: 80, rows: 24 };
+    const result = roundTrip(msg);
+    expect(result).toEqual(msg);
+    if (result.type === 'attach') {
+      expect(result.compression).toBeUndefined();
+    }
+  });
+
   it('encodes/decodes detach', () => {
     const msg: HostRequest = { type: 'detach' };
     const result = roundTrip(msg);
@@ -166,6 +184,24 @@ describe('HostEvent round-trip', () => {
     expect(result).toEqual(msg);
   });
 
+  it('encodes/decodes attached with compression', () => {
+    const msg: HostEvent = { type: 'attached', paneId: '%1', compression: 'deflate' };
+    const result = roundTrip(msg);
+    expect(result).toEqual(msg);
+    if (result.type === 'attached') {
+      expect(result.compression).toBe('deflate');
+    }
+  });
+
+  it('encodes/decodes attached without compression (field absent)', () => {
+    const msg: HostEvent = { type: 'attached', paneId: '%1' };
+    const result = roundTrip(msg);
+    expect(result).toEqual(msg);
+    if (result.type === 'attached') {
+      expect(result.compression).toBeUndefined();
+    }
+  });
+
   it('encodes/decodes detached', () => {
     const msg: HostEvent = { type: 'detached' };
     const result = roundTrip(msg);
@@ -367,6 +403,16 @@ describe('decode structural validation', () => {
       expect(() => decodeMalformed({ type: 'attach', paneId: '%1', cols: 80, rows: Infinity }))
         .toThrow('attach: "rows" must be a finite number');
     });
+
+    it('accepts valid compression string', () => {
+      expect(() => decodeMalformed({ type: 'attach', paneId: '%1', cols: 80, rows: 24, compression: 'deflate' }))
+        .not.toThrow();
+    });
+
+    it('rejects non-string compression', () => {
+      expect(() => decodeMalformed({ type: 'attach', paneId: '%1', cols: 80, rows: 24, compression: 123 }))
+        .toThrow('attach: "compression" must be a string');
+    });
   });
 
   describe('input', () => {
@@ -441,6 +487,16 @@ describe('decode structural validation', () => {
       expect(() => decodeMalformed({ type: 'attached' }))
         .toThrow('attached: "paneId" must be a string');
     });
+
+    it('accepts valid compression string', () => {
+      expect(() => decodeMalformed({ type: 'attached', paneId: '%1', compression: 'deflate' }))
+        .not.toThrow();
+    });
+
+    it('rejects non-string compression', () => {
+      expect(() => decodeMalformed({ type: 'attached', paneId: '%1', compression: 123 }))
+        .toThrow('attached: "compression" must be a string');
+    });
   });
 
   describe('session_ended', () => {

src/codec.ts

@@ -89,6 +89,9 @@ function validateFields(msg: Record<string, unknown>): void {
       if ('reattach' in msg && typeof msg['reattach'] !== 'boolean') {
         throw new Error('attach: "reattach" must be a boolean');
       }
+      if ('compression' in msg && typeof msg['compression'] !== 'string') {
+        throw new Error('attach: "compression" must be a string');
+      }
       break;
 
     case 'input':
@@ -118,6 +121,9 @@ function validateFields(msg: Record<string, unknown>): void {
 
     case 'attached':
       assertString(msg, 'attached', 'paneId');
+      if ('compression' in msg && typeof msg['compression'] !== 'string') {
+        throw new Error('attached: "compression" must be a string');
+      }
       break;
 
     case 'session_ended':

src/protocol.ts

@@ -18,6 +18,7 @@ export interface AttachRequest {
   cols: number;
   rows: number;
   reattach?: boolean;
+  compression?: 'deflate';
 }
 
 export interface DetachRequest {
@@ -68,6 +69,7 @@ export interface OutputEvent {
 export interface AttachedEvent {
   type: 'attached';
   paneId: string;
+  compression?: 'deflate';
 }
 
 export interface DetachedEvent {