feat(ai): PR 3 — Parsers + Execute Agent

source/agent-parser.js

@@ -0,0 +1,108 @@
+import { createError } from 'error-causes';
+import { ParseError } from './ai-errors.js';
+
+/**
+ * Parse a string result from an agent, attempting multiple strategies:
+ * 1. Direct JSON parse if string starts with { or [
+ * 2. Extract and parse markdown-wrapped JSON (```json\n...\n```)
+ * 3. Keep as plain text if neither works
+ */
+export const parseStringResult = (result, logger) => {
+  const trimmed = result.trim();
+
+  if (trimmed.startsWith('{') || trimmed.startsWith('[')) {
+    try {
+      const parsed = JSON.parse(trimmed);
+      logger.log('Successfully parsed string as JSON');
+      return parsed;
+    } catch {
+      logger.log('Direct JSON parse failed, trying markdown extraction');
+    }
+  }
+
+  const markdownMatch = result.match(/```(?:json)?\s*\n([\s\S]*?)\n```/);
+  if (markdownMatch) {
+    logger.log('Found markdown-wrapped JSON, extracting...');
+    try {
+      const parsed = JSON.parse(markdownMatch[1]);
+      logger.log('Successfully parsed markdown-wrapped JSON');
+      return parsed;
+    } catch {
+      logger.log('Failed to parse markdown content, keeping original string');
+    }
+  }
+
+  logger.log('String is not valid JSON, keeping as plain text');
+  return result;
+};
+
+/**
+ * Parse OpenCode's NDJSON output, extracting and concatenating all "text" events.
+ */
+export const parseOpenCodeNDJSON = (ndjson, logger) => {
+  logger.log('Parsing OpenCode NDJSON output...');
+
+  const lines = ndjson.trim().split('\n').filter(line => line.trim());
+
+  const textEvents = lines.reduce((acc, line) => {
+    try {
+      const event = JSON.parse(line);
+      if (event.type === 'text' && event.part?.text) {
+        logger.log(`Found text event with ${event.part.text.length} characters`);
+        return [...acc, event.part.text];
+      }
+    } catch (err) {
+      logger.log(`Warning: Failed to parse NDJSON line: ${err.message}`);
+    }
+    return acc;
+  }, []);
+
+  if (textEvents.length === 0) {
+    throw createError({
+      ...ParseError,
+      message: 'No text events found in OpenCode output',
+      code: 'NO_TEXT_EVENTS',
+      ndjsonLength: ndjson.length,
+      linesProcessed: lines.length
+    });
+  }
+
+  const combinedText = textEvents.join('');
+  logger.log(`Combined ${textEvents.length} text event(s) into ${combinedText.length} characters`);
+  return combinedText;
+};
+
+/**
+ * Unwrap a JSON envelope object { result: ... }, returning the inner value.
+ * If no envelope is present, returns the object as-is.
+ * Shared helper used by unwrapAgentResult and execute-agent's raw output handling.
+ */
+export const unwrapEnvelope = (parsed) =>
+  parsed?.result !== undefined ? parsed.result : parsed;
+
+/**
+ * Unwrap agent result from potential JSON envelope and parse nested JSON.
+ * Handles Claude CLI's envelope format { result: "..." } and nested JSON strings.
+ * @throws {Error} If output is not valid JSON after all parsing attempts
+ */
+export const unwrapAgentResult = (processedOutput, logger) => {
+  const parsed = parseStringResult(processedOutput, logger);
+
+  if (typeof parsed === 'string') {
+    throw createError({
+      ...ParseError,
+      message: `Agent output is not valid JSON: ${parsed.slice(0, 100)}`,
+      outputPreview: parsed.slice(0, 100)
+    });
+  }
+
+  const unwrapped = unwrapEnvelope(parsed);
+
+  logger.log(`Parsed result type: ${typeof unwrapped}`);
+  if (typeof unwrapped === 'string') {
+    logger.log('Result is string, attempting to parse as JSON');
+    return parseStringResult(unwrapped, logger);
+  }
+
+  return unwrapped;
+};