Reply Forge

Paste X post text → get a sharp, factual 50-word reply.

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🔑 Add your Anthropic API key

Get a free key at console.anthropic.com → API Keys. Saved only in your browser.

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Paste tweet text

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💡 Copy the text from X — URLs alone won't work

\n\n Reply vibe\n

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Crafting your reply…

\n ✦ Your Reply\n —\n

Key facts used

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\n\n\n`;\n\nexport default async function handler(req: Request): Promise {\n const url = new URL(req.url);\n\n // Serve the HTML page\n if (req.method === \"GET\") {\n return new Response(HTML, { headers: { \"Content-Type\": \"text/html\" } });\n }\n\n // API proxy endpoint — avoids CORS entirely since this runs server-side\n if (req.method === \"POST\" && url.pathname === \"/api\") {\n try {\n const { key, input, tone } = await req.json();\n\n if (!key || !key.startsWith(\"sk-ant-\")) {\n return Response.json({ error: \"Invalid API key\" }, { status: 400 });\n }\n if (!input) {\n return Response.json({ error: \"No input provided\" }, { status: 400 });\n }\n\n const toneMap: Record = {\n energetic:\n \"enthusiastic, punchy, high-energy — active verbs, exclamation where natural\",\n witty: \"clever, light, a touch of humor — smart but not snarky\",\n authoritative:\n \"confident, expert, data-forward — commanding and credible\",\n supportive:\n \"warm, affirming, constructive — backing the person with facts\",\n contrarian:\n \"bold, respectfully challenging — pushback grounded only in the post\",\n };\n\n const anthropicRes = await fetch(\n \"https://api.anthropic.com/v1/messages\",\n {\n method: \"POST\",\n headers: {\n \"Content-Type\": \"application/json\",\n \"x-api-key\": key,\n \"anthropic-version\": \"2023-06-01\",\n },\n body: JSON.stringify({\n model: \"claude-sonnet-4-5-20250929\",\n max_tokens: 400,\n system:\n `You are a social media reply expert. Write a reply to the X (Twitter) post the user provides.\nRULES:\n- Max 50 words. Count every word.\n- Tone: ${toneMap[tone] || toneMap.energetic}\n- Only use facts stated in the post. Never invent anything.\n- You MUST always respond with ONLY a raw JSON object — no markdown, no code fences, no text outside the JSON.\n- If you can write a reply: {\"reply\":\"your reply\",\"keyFacts\":[\"fact1\",\"fact2\"],\"error\":\"\"}\n- If you choose not to write a reply: {\"reply\":\"\",\"keyFacts\":[],\"error\":\"one sentence explanation\"}`,\n messages: [{ role: \"user\", content: input }],\n }),\n },\n );\n\n const anthropicData = await anthropicRes.json();\n\n if (!anthropicRes.ok) {\n return Response.json(\n {\n error: anthropicData?.error?.message ||\n \"Anthropic API error \" + anthropicRes.status,\n },\n { status: 502 },\n );\n }\n\n const raw = (anthropicData.content || [])\n .filter((b: any) => b.type === \"text\")\n .map((b: any) => b.text)\n .join(\"\")\n .trim();\n\n if (!raw) {\n return Response.json({\n error: \"Empty response from AI. Stop reason: \" +\n anthropicData.stop_reason,\n }, { status: 502 });\n }\n\n // Parse JSON robustly\n let parsed: any = null;\n for (\n const fn of [\n () => JSON.parse(raw),\n () => JSON.parse(raw.replace(/```json|```/gi, \"\").trim()),\n () => {\n const m = raw.match(/\\{[\\s\\S]*\\}/);\n if (m) return JSON.parse(m[0]);\n throw new Error(\"no json\");\n },\n ]\n ) {\n try {\n parsed = fn();\n if (parsed) break;\n } catch {}\n }\n\n // If we couldn't parse JSON, Claude responded in plain text — return it as the error\n if (!parsed) {\n return Response.json({ error: raw }, { status: 200 });\n }\n\n return Response.json(parsed);\n } catch (e: any) {\n return Response.json({ error: e.message }, { status: 500 });\n }\n }\n\n return new Response(\"Not found\", { status: 404 });\n}","deleted","label",[100],"permalink","https://www.val.town/x/ChiefP/untitled-5827/code/main.ts","extension","actionData","errors"]