diff --git a/studio/ai_chat.go b/studio/ai_chat.go
new file mode 100644
index 0000000..77bdcd0
--- /dev/null
+++ b/studio/ai_chat.go
@@ -0,0 +1,183 @@
+package main
+
+import (
+ "bytes"
+ "context"
+ "encoding/json"
+ "fmt"
+ "io"
+ "net/http"
+ "time"
+)
+
+const (
+ chatModel = "claude-sonnet-4-6"
+ chatAPIURL = "https://api.anthropic.com/v1/messages"
+ chatAPIVersion = "2023-06-01"
+ chatMaxTokens = 4096
+
+ // Sonnet 4.6 pricing per 1M tokens (USD)
+ priceInputPer1M = 3.0
+ priceOutputPer1M = 15.0
+)
+
+// ChatMessage is one turn in the conversation.
+type ChatMessage struct {
+ Role string `json:"role"`
+ Content string `json:"content"`
+}
+
+// ChatResponse is returned from the Chat method.
+type ChatResponse struct {
+ Content string `json:"content"`
+ InputTokens int `json:"inputTokens"`
+ OutputTokens int `json:"outputTokens"`
+ CostUSD float64 `json:"costUSD"`
+}
+
+var chatHTTPClient = &http.Client{Timeout: 120 * time.Second}
+
+// GetAPIKey retrieves the stored Anthropic API key from the platform keychain.
+// Returns an empty string (not an error) when no key is stored.
+func (a *App) GetAPIKey() (string, error) {
+ key, err := keychainGet()
+ if err != nil {
+ return "", nil
+ }
+ return key, nil
+}
+
+// SetAPIKey stores the Anthropic API key in the platform keychain.
+func (a *App) SetAPIKey(key string) error {
+ if key == "" {
+ return keychainDelete()
+ }
+ return keychainSet(key)
+}
+
+// DeleteAPIKey removes the stored API key from the platform keychain.
+func (a *App) DeleteAPIKey() error {
+ return keychainDelete()
+}
+
+// Chat sends a multi-turn conversation to the Claude API and returns the
+// assistant reply together with token usage for the cost counter.
+//
+// messages is the full conversation history (user + assistant alternating).
+// fileContent is the current editor file, injected into the system prompt.
+func (a *App) Chat(messages []ChatMessage, fileContent string) (ChatResponse, error) {
+ apiKey, _ := keychainGet()
+ if apiKey == "" {
+ return ChatResponse{}, fmt.Errorf("no API key stored — add your Anthropic key in the AI panel")
+ }
+
+ systemPrompt := `You are an expert FlutterProbe test assistant. You help users write, debug, and improve ProbeScript test files.
+
+ProbeScript syntax reference:
+- Tests: test "name" (indented steps below)
+- Steps: tap "Text", tap #key, type "value" into "Field", see "Text", wait until "Text" appears, swipe up/down/left/right, scroll up/down, go back, open the app, take screenshot "name"
+- Conditional: tap "X" if visible, wait until "X" appears
+- Tags on next line: @smoke @critical
+
+Keep answers concise. When suggesting changes, output valid ProbeScript.`
+
+ if fileContent != "" {
+ systemPrompt += "\n\nCurrent file:\n```\n" + fileContent + "\n```"
+ }
+
+ type reqMsg struct {
+ Role string `json:"role"`
+ Content string `json:"content"`
+ }
+ type reqBody struct {
+ Model string `json:"model"`
+ MaxTokens int `json:"max_tokens"`
+ System string `json:"system"`
+ Messages []reqMsg `json:"messages"`
+ }
+
+ msgs := make([]reqMsg, len(messages))
+ for i, m := range messages {
+ msgs[i] = reqMsg{Role: m.Role, Content: m.Content}
+ }
+
+ payload, err := json.Marshal(reqBody{
+ Model: chatModel,
+ MaxTokens: chatMaxTokens,
+ System: systemPrompt,
+ Messages: msgs,
+ })
+ if err != nil {
+ return ChatResponse{}, fmt.Errorf("marshal: %w", err)
+ }
+
+ ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
+ defer cancel()
+
+ req, err := http.NewRequestWithContext(ctx, http.MethodPost, chatAPIURL, bytes.NewReader(payload))
+ if err != nil {
+ return ChatResponse{}, err
+ }
+ req.Header.Set("Content-Type", "application/json")
+ req.Header.Set("x-api-key", apiKey)
+ req.Header.Set("anthropic-version", chatAPIVersion)
+
+ resp, err := chatHTTPClient.Do(req)
+ if err != nil {
+ return ChatResponse{}, fmt.Errorf("request: %w", err)
+ }
+ defer resp.Body.Close()
+
+ body, err := io.ReadAll(resp.Body)
+ if err != nil {
+ return ChatResponse{}, fmt.Errorf("read response: %w", err)
+ }
+
+ if resp.StatusCode == 401 {
+ return ChatResponse{}, fmt.Errorf("invalid API key — check your key in the AI panel")
+ }
+ if resp.StatusCode == 429 {
+ return ChatResponse{}, fmt.Errorf("rate limited — try again shortly")
+ }
+ if resp.StatusCode != 200 {
+ return ChatResponse{}, fmt.Errorf("API error %d: %s", resp.StatusCode, string(body))
+ }
+
+ var apiResp struct {
+ Content []struct {
+ Type string `json:"type"`
+ Text string `json:"text"`
+ } `json:"content"`
+ Error *struct {
+ Message string `json:"message"`
+ } `json:"error"`
+ Usage struct {
+ InputTokens int `json:"input_tokens"`
+ OutputTokens int `json:"output_tokens"`
+ } `json:"usage"`
+ }
+ if err := json.Unmarshal(body, &apiResp); err != nil {
+ return ChatResponse{}, fmt.Errorf("parse response: %w", err)
+ }
+ if apiResp.Error != nil {
+ return ChatResponse{}, fmt.Errorf("API error: %s", apiResp.Error.Message)
+ }
+
+ text := ""
+ for _, c := range apiResp.Content {
+ if c.Type == "text" {
+ text += c.Text
+ }
+ }
+
+ in := apiResp.Usage.InputTokens
+ out := apiResp.Usage.OutputTokens
+ cost := float64(in)*priceInputPer1M/1_000_000 + float64(out)*priceOutputPer1M/1_000_000
+
+ return ChatResponse{
+ Content: text,
+ InputTokens: in,
+ OutputTokens: out,
+ CostUSD: cost,
+ }, nil
+}
diff --git a/studio/frontend/index.html b/studio/frontend/index.html
index 4c6770e..bcf5339 100644
--- a/studio/frontend/index.html
+++ b/studio/frontend/index.html
@@ -30,6 +30,7 @@
+
@@ -97,6 +98,29 @@
+
+
+ AI Chat claude-sonnet-4-6 · BYOK
+
+
+
+
+
+
+
+
+
+
+
+
+
@@ -175,6 +199,7 @@
Keyboard shortcuts
⌘B
Connect / disconnect device
⌘P
Open workspace folder
⌘K
Refresh device list
+
⌘⇧A
Toggle AI chat
?
Show this help
Esc
Close this help
@@ -185,6 +210,27 @@
Keyboard shortcuts
+
+
+
+
Anthropic API key
+
+
+
+ Your key is stored in the system keychain (macOS Keychain / Windows Credential Manager /
+ Linux libsecret). It is never written to disk or sent anywhere other than api.anthropic.com.
+