From ba3b271c39affc0a145cb9953a34e63bfdda5577 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Tue, 25 Nov 2025 01:41:52 +0100
Subject: [PATCH] Parse Claude JSON output to return text replies

---
 src/index.core.test.ts | 32 +++++++++++++++++-
 src/index.ts           | 74 ++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 103 insertions(+), 3 deletions(-)

diff --git a/src/index.core.test.ts b/src/index.core.test.ts
index 22b1d1e8c..1515af09b 100644
--- a/src/index.core.test.ts
+++ b/src/index.core.test.ts
@@ -172,13 +172,43 @@ describe("config and templating", () => {
 		const argv = runSpy.mock.calls[0][0];
 		expect(argv[0]).toBe("claude");
 		expect(argv.at(-1)).toBe("hi");
+		// The helper should auto-add print and output format flags without disturbing the prompt position.
 		expect(argv.includes("-p") || argv.includes("--print")).toBe(true);
 		const outputIdx = argv.findIndex(
-			(part) => part === "--output-format" || part.startsWith("--output-format="),
+			(part) =>
+				part === "--output-format" || part.startsWith("--output-format="),
 		);
 		expect(outputIdx).toBeGreaterThan(-1);
 		expect(argv[outputIdx + 1]).toBe("text");
 	});
+
+	it("parses Claude JSON output and returns text content", async () => {
+		const runSpy = vi.spyOn(index, "runCommandWithTimeout").mockResolvedValue({
+			stdout: '{"text":"hello world"}\n',
+			stderr: "",
+			code: 0,
+			signal: null,
+			killed: false,
+		});
+		const cfg = {
+			inbound: {
+				reply: {
+					mode: "command" as const,
+					command: ["claude", "{{Body}}"],
+					claudeOutputFormat: "json" as const,
+				},
+			},
+		};
+
+		const result = await index.getReplyFromConfig(
+			{ Body: "hi", From: "+1", To: "+2" },
+			undefined,
+			cfg,
+			runSpy,
+		);
+
+		expect(result).toBe("hello world");
+	});
 });
 
 describe("twilio interactions", () => {
diff --git a/src/index.ts b/src/index.ts
index a3377e2fe..a6af05896 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -552,11 +552,69 @@ type TemplateContext = MsgContext & {
 	IsNewSession?: string;
 };
 
+function extractClaudeText(payload: unknown): string | undefined {
+	// Best-effort walker to find the primary text field in Claude JSON outputs.
+	if (payload == null) return undefined;
+	if (typeof payload === "string") return payload;
+	if (Array.isArray(payload)) {
+		for (const item of payload) {
+			const found = extractClaudeText(item);
+			if (found) return found;
+		}
+		return undefined;
+	}
+	if (typeof payload === "object") {
+		const obj = payload as Record<string, unknown>;
+		if (typeof obj.text === "string") return obj.text;
+		if (typeof obj.completion === "string") return obj.completion;
+		if (typeof obj.output === "string") return obj.output;
+		if (obj.message) {
+			const inner = extractClaudeText(obj.message);
+			if (inner) return inner;
+		}
+		if (Array.isArray(obj.messages)) {
+			const inner = extractClaudeText(obj.messages);
+			if (inner) return inner;
+		}
+		if (Array.isArray(obj.content)) {
+			for (const block of obj.content) {
+				if (
+					block &&
+					typeof block === "object" &&
+					(block as { type?: string }).type === "text" &&
+					typeof (block as { text?: unknown }).text === "string"
+				) {
+					return (block as { text: string }).text;
+				}
+				const inner = extractClaudeText(block);
+				if (inner) return inner;
+			}
+		}
+	}
+	return undefined;
+}
+
+function parseClaudeJsonText(raw: string): string | undefined {
+	// Handle a single JSON blob or newline-delimited JSON; return the first extracted text.
+	const candidates = [raw, ...raw.split(/\n+/).map((s) => s.trim()).filter(Boolean)];
+	for (const candidate of candidates) {
+		try {
+			const parsed = JSON.parse(candidate);
+			const text = extractClaudeText(parsed);
+			if (text) return text;
+		} catch {
+			// ignore parse errors; try next candidate
+		}
+	}
+	return undefined;
+}
+
 type SessionEntry = { sessionId: string; updatedAt: number };
 
 const SESSION_STORE_DEFAULT = path.join(CONFIG_DIR, "sessions.json");
 const DEFAULT_RESET_TRIGGER = "/new";
 const DEFAULT_IDLE_MINUTES = 60;
+const CLAUDE_BIN = "claude";
 
 function resolveStorePath(store?: string) {
 	if (!store) return SESSION_STORE_DEFAULT;
@@ -722,7 +780,7 @@ async function getReplyFromConfig(
 		if (
 			reply.claudeOutputFormat &&
 			argv.length > 0 &&
-			path.basename(argv[0]) === "claude"
+			path.basename(argv[0]) === CLAUDE_BIN
 		) {
 			const hasOutputFormat = argv.some(
 				(part) =>
@@ -773,10 +831,22 @@ async function getReplyFromConfig(
 				finalArgv,
 				timeoutMs,
 			);
-			const trimmed = stdout.trim();
+			let trimmed = stdout.trim();
 			if (stderr?.trim()) {
 				logVerbose(`Command auto-reply stderr: ${stderr.trim()}`);
 			}
+			if (reply.claudeOutputFormat === "json" && trimmed) {
+				// Claude JSON mode: extract the human text for both logging and reply.
+				const extracted = parseClaudeJsonText(trimmed);
+				if (extracted) {
+					logVerbose(
+						`Claude JSON parsed -> ${extracted.slice(0, 120)}${extracted.length > 120 ? "…" : ""}`,
+					);
+					trimmed = extracted.trim();
+				} else {
+					logVerbose("Claude JSON parse failed; returning raw stdout");
+				}
+			}
 			logVerbose(
 				`Command auto-reply stdout (trimmed): ${trimmed || "<empty>"}`,
 			);