Patch 5: Replace silent truncation with explicit token limit in read-text-file

Silent truncation of legal documents is unacceptable - Merlyn was reading
partial files without knowing it.

New behavior:
- Files under AGENT_MAX_FILE_TOKENS (default 500,000): return full content
- Files over limit: return explicit message with token count and options
- Paralegal controls any summarization decision
- Merlyn never silently truncates legal documents

server/utils/agents/aibitat/plugins/filesystem/read-text-file.js

@@ -104,19 +104,23 @@ module.exports.FilesystemReadTextFile = {
                 this.super.introspect(`Successfully read ${filePath}`);
               }
 
-              const { content: finalContent, wasTruncated } =
-                filesystem.truncateContentForContext(
-                  content,
-                  this.super,
-                  "[Content truncated - file exceeds context limit. Use head/tail parameters to read specific portions.]"
-                );
+              const { TokenManager } = require("../../../../helpers/tiktoken");
+              const tokenManager = new TokenManager(this.super.model);
+              const tokenCount = tokenManager.countFromString(content);
+              const maxFileTokens = Number(process.env.AGENT_MAX_FILE_TOKENS) || 500_000;
 
-              if (wasTruncated) {
-                this.super.introspect(
-                  `${this.caller}: File content was truncated to fit context limit`
-                );
+              if (tokenCount > maxFileTokens) {
+                  return [
+                      `File "${filePath}" contains ${tokenCount.toLocaleString()} tokens, which exceeds the limit of ${maxFileTokens.toLocaleString()} tokens.`,
+                      `To proceed, choose one of the following options:`,
+                      `1. Read specific portions using the head or tail parameters`,
+                      `2. Search for specific content using search-files`,
+                      `3. Request a summary of the file`,
+                  ].join("\n");
               }
 
+const finalContent = content;
+
               const filename = path.basename(validPath);
               this.super.addCitation?.({
                 id: `fs-${Buffer.from(validPath).toString("base64url").slice(0, 32)}`,