fix(prd): prevent non-JSON output from conversion by disabling tools

Claude was attempting to use the Write tool during PRD conversion,
and when denied, fell back to conversational output with preamble
text before the JSON. Fix by disabling all tools via --tools ""
and passing the prompt through stdin, updating the prompt to
explicitly forbid tool use, and hardening cleanJSONOutput to
extract JSON objects from any surrounding preamble text.

Author: MiniCodeMonkey

embed/convert_prompt.txt

@@ -6,7 +6,7 @@ Here is the PRD content:
 {{PRD_CONTENT}}
 </prd>
 
-Return ONLY valid JSON — no markdown fences, no explanation, no commentary. The JSON must follow this exact structure:
+Do NOT use any tools. Do NOT write any files. Output ONLY the raw JSON to stdout — no markdown fences, no explanation, no preamble, no commentary. The JSON must follow this exact structure:
 
 {
   "project": "Project Name",

internal/prd/generator.go

@@ -189,8 +189,9 @@ func runClaudeConversion(absPRDDir string) (string, error) {
 
 	prompt := embed.GetConvertPrompt(string(content))
 
-	cmd := exec.Command("claude", "-p", prompt)
+	cmd := exec.Command("claude", "-p", "--tools", "")
 	cmd.Dir = absPRDDir
+	cmd.Stdin = strings.NewReader(prompt)
 
 	var stdout, stderr bytes.Buffer
 	cmd.Stdout = &stdout
@@ -592,7 +593,8 @@ func NeedsConversion(prdDir string) (bool, error) {
 	return mdInfo.ModTime().After(jsonInfo.ModTime()), nil
 }
 
-// cleanJSONOutput removes markdown code blocks and trims whitespace from Claude's output.
+// cleanJSONOutput removes markdown code blocks, conversational preamble, and trims
+// whitespace from Claude's output to extract the JSON object.
 func cleanJSONOutput(output string) string {
 	output = strings.TrimSpace(output)
 
@@ -607,6 +609,55 @@ func cleanJSONOutput(output string) string {
 		output = strings.TrimSuffix(output, "```")
 	}
 
+	output = strings.TrimSpace(output)
+
+	// If output doesn't start with '{', Claude may have added preamble text.
+	// Extract the JSON object by finding the first '{' and matching closing '}'.
+	if len(output) > 0 && output[0] != '{' {
+		start := strings.Index(output, "{")
+		if start == -1 {
+			return output // No JSON object found, return as-is for error handling
+		}
+		// Find the matching closing brace by counting brace depth
+		depth := 0
+		inString := false
+		escaped := false
+		end := -1
+		for i := start; i < len(output); i++ {
+			if escaped {
+				escaped = false
+				continue
+			}
+			ch := output[i]
+			if ch == '\\' && inString {
+				escaped = true
+				continue
+			}
+			if ch == '"' {
+				inString = !inString
+				continue
+			}
+			if inString {
+				continue
+			}
+			if ch == '{' {
+				depth++
+			} else if ch == '}' {
+				depth--
+				if depth == 0 {
+					end = i
+					break
+				}
+			}
+		}
+		if end != -1 {
+			output = output[start : end+1]
+		} else {
+			// No matching closing brace; take from first '{' to end
+			output = output[start:]
+		}
+	}
+
 	return strings.TrimSpace(output)
 }
 

internal/prd/generator_test.go

@@ -34,6 +34,31 @@ func TestCleanJSONOutput(t *testing.T) {
 			input:    "  \n{\"project\": \"test\"}\n  ",
 			expected: `{"project": "test"}`,
 		},
+		{
+			name:     "with conversational preamble",
+			input:    "Since the file write is being denied, here's the JSON output directly:\n\n{\"project\": \"test\"}",
+			expected: `{"project": "test"}`,
+		},
+		{
+			name:     "with preamble and nested objects",
+			input:    "Here is the JSON:\n{\"project\": \"test\", \"userStories\": [{\"id\": \"US-001\"}]}",
+			expected: `{"project": "test", "userStories": [{"id": "US-001"}]}`,
+		},
+		{
+			name:     "with preamble and trailing text",
+			input:    "Here you go:\n{\"project\": \"test\"}\nLet me know if you need changes.",
+			expected: `{"project": "test"}`,
+		},
+		{
+			name:     "with code fence and preamble",
+			input:    "Here is the output:\n```json\n{\"project\": \"test\"}\n```",
+			expected: `{"project": "test"}`,
+		},
+		{
+			name:     "JSON with escaped quotes in preamble scenario",
+			input:    "Output:\n{\"project\": \"test \\\"quoted\\\"\"}",
+			expected: `{"project": "test \"quoted\""}`,
+		},
 	}
 
 	for _, tt := range tests {