feat(observer): v15 AG Native chat relay — scanChatBodies dual strategy (#632)

- Add AG Native DOM path: #conversation + .leading-relaxed.select-text
- Keep Cascade path: [data-testid=conversation-view] + [data-step-index]
- Register #632 in known-issues.md (SDK+DOM both blocked for AG Native)
- Bump version 0.5.50 → 0.5.51
- Add DOM analysis helper scripts

extension/src/observer-script.ts

@@ -1,7 +1,7 @@
 export function generateApprovalObserverScript(_port: number): string {
   return `
-// ── Gravity Bridge v14: Strict Scope + Junk Filter ──
-// v14: Strict 5-level DOM scope, CSS/source code/icon-glue filters, no fallback
+// ── Gravity Bridge v15: AG Native Chat Relay ──
+// v15: AG Native #conversation + .leading-relaxed.select-text chat body scanning
 (function(){
   'use strict';
   var BASE='',_obs=false,_sent={},_ready=false;
@@ -10,7 +10,7 @@ export function generateApprovalObserverScript(_port: number): string {
   var CLEANUP_MS=300000;
 
   function log(m){console.log('[GB Observer] '+m);}
-  log('v14 Script loaded — Strict Scope + Junk Filter');
+  log('v15 Script loaded — AG Native Chat Relay');
 
   // DIAGNOSTIC BEACON: immediate POST to confirm script execution in renderer
   try {
@@ -460,15 +460,16 @@ export function generateApprovalObserverScript(_port: number): string {
   }
 
   // ══════════════════════════════════════════════════════════════════
-  // v7: STEP-AWARE CHAT BODY SCANNING
-  // Scans [data-step-index] elements inside [data-testid="conversation-view"]
-  // Extracts AI response text while filtering UI noise
+  // v15: AG-NATIVE + CASCADE DUAL CHAT BODY SCANNING
+  // AG Native: #conversation > ... > .leading-relaxed.select-text
+  // Cascade:   [data-testid="conversation-view"] > [data-step-index]
   // ══════════════════════════════════════════════════════════════════
 
   var _lastScrapedStepIndex = -1;
   var _lastStepText = '';
   var _lastStepTextTime = 0;
   var _lastStepTextSent = false;
+  var _lastResponseBlockCount = 0; // track number of response blocks for AG Native
 
   function extractCleanStepText(stepEl) {
     if (!stepEl) return '';
@@ -495,7 +496,7 @@ export function generateApprovalObserverScript(_port: number): string {
     }
 
     // Try to get text from markdown rendering area first
-    // Look for known markdown container patterns
+    // AG Native uses .leading-relaxed.select-text, Cascade uses .markdown-body/.prose
     var mdEl = clone.querySelector('.markdown-body, .prose, [class*="markdown"], [class*="rendered"]');
     var rawText = '';
     if (mdEl && mdEl.innerText && mdEl.innerText.trim().length > 10) {
@@ -515,8 +516,80 @@ export function generateApprovalObserverScript(_port: number): string {
     // One-time DOM dump
     dumpDOMStructure();
 
-    // PRIMARY: Find conversation-view container
-    var cv = document.querySelector('[data-testid="conversation-view"]');
+    // ── STRATEGY 1: AG Native — #conversation or .antigravity-agent-side-panel ──
+    var cv = document.querySelector('#conversation');
+    if (!cv) {
+      cv = document.querySelector('.antigravity-agent-side-panel');
+    }
+
+    if (cv) {
+      // AG Native path: find AI response blocks by class pattern
+      // DOM structure: #conversation > ... > .leading-relaxed.select-text (AI response text)
+      var responseBlocks = cv.querySelectorAll('.leading-relaxed.select-text');
+
+      if (responseBlocks.length > 0) {
+        // Process the LAST (most recent) response block
+        var lastBlock = responseBlocks[responseBlocks.length - 1];
+
+        // Skip if already scraped
+        if (lastBlock.dataset.agChatScraped === 'true' || lastBlock.dataset.agChatScraped === 'pending') {
+          // Check for NEW blocks since last scrape
+          if (responseBlocks.length > _lastResponseBlockCount) {
+            // New block appeared — process it
+            for (var rbi = responseBlocks.length - 1; rbi >= 0; rbi--) {
+              if (responseBlocks[rbi].dataset.agChatScraped !== 'true' && responseBlocks[rbi].dataset.agChatScraped !== 'pending') {
+                lastBlock = responseBlocks[rbi];
+                break;
+              }
+            }
+            if (lastBlock.dataset.agChatScraped === 'true' || lastBlock.dataset.agChatScraped === 'pending') return;
+          } else {
+            return; // Already scraped, no new blocks
+          }
+        }
+
+        var blockText = extractCleanStepText(lastBlock);
+        if (blockText && blockText.length > 30) {
+          // QUALITY CHECK: Skip if the text is mostly short lines (UI artifacts)
+          var lines = blockText.split('\\n').filter(function(l) { return l.trim().length > 0; });
+          var longLines = lines.filter(function(l) { return l.trim().length > 20; });
+          if (longLines.length === 0) {
+            log('AG-Native: skipped (no long lines, likely UI noise)');
+            return;
+          }
+
+          // Wait for content to stabilize (3s no change)
+          if (_lastStepText !== blockText) {
+            _lastStepText = blockText;
+            _lastStepTextTime = Date.now();
+            _lastStepTextSent = false;
+            return; // Wait for next scan cycle
+          }
+
+          if (_lastStepTextSent) return;
+          if (Date.now() - _lastStepTextTime < 3000) return; // Still waiting
+
+          // Content is stable — send it
+          _lastStepTextSent = true;
+          _lastResponseBlockCount = responseBlocks.length;
+          lastBlock.dataset.agChatScraped = 'pending';
+
+          log('AG-Native chat relay: blocks=' + responseBlocks.length + ' text=' + blockText.length + ' chars');
+          (function(el, txt, count) {
+            fetch(BASE + '/chat', {
+              method: 'POST',
+              headers: { 'Content-Type': 'application/json' },
+              body: JSON.stringify({ text: txt, source: 'ag_native_block_' + count, block_index: count })
+            }).then(function() { el.dataset.agChatScraped = 'true'; log('AG-Native chat sent OK'); })
+              .catch(function(e) { el.dataset.agChatScraped = 'false'; log('AG-Native chat send error: ' + e.message); });
+          })(lastBlock, blockText, responseBlocks.length);
+        }
+        return; // AG Native path handled — don't fall through to Cascade path
+      }
+    }
+
+    // ── STRATEGY 2: Cascade — [data-testid="conversation-view"] ──
+    cv = document.querySelector('[data-testid="conversation-view"]');
     if (!cv) {
       // FALLBACK: Try older selectors
       cv = document.querySelector('[class*="conversation"], [class*="chat-container"]');