캐시 진단

Turn 2: reference the previous turn so the API can compare prefixes

curl -sS --fail-with-body https://api.anthropic.com/v1/messages
-H "x-api-key: $ANTHR...KEY"
-H "anthropic-version: 2023-06-01"
-H "anthropic-beta: cache-diagnosis-2026-04-07"
-H "content-type: application/json"
-d @- <<EOF | jq '{id, diagnostics}' # diagnostics: null means no divergence was found { "model": "claude-opus-5-5", "max_tokens": 1024, "cache_control": {"type": "ephemeral"}, "system": "You are an AI assistant analyzing a large document. ...", "messages": [ {"role": "user", "content": "Summarize section 1."}, {"role": "assistant", "content": "Section 1 covers..."}, {"role": "user", "content": "Now summarize section 2."} ], "diagnostics": {"previous_message_id": "$message_id"} } EOF

```bash CLI
# Turn 1
turn1=$(ant beta:messages create \
  --beta cache-diagnosis-2026-04-07 \
  --transform '{id,usage,diagnostics}' <<'YAML'
model: claude-opus-5-5
max_tokens: 1024
cache_control:
  type: ephemeral
system: "You are an AI assistant analyzing a large document. <document>...</document>"
messages:
  - role: user
    content: Summarize section 1.
diagnostics:
  previous_message_id: null
YAML
)
printf '%s\n' "$turn1"

# Turn 2: pass the id from turn 1 as previous_message_id
message_id=$(jq -r '.id' <<<"$turn1")
ant beta:messages create \
  --beta cache-diagnosis-2026-04-07 \
  --transform '{id,usage,diagnostics}' <<YAML
model: claude-opus-5-5
max_tokens: 1024
cache_control:
  type: ephemeral
system: "You are an AI assistant analyzing a large document. <document>...</document>"
messages:
  - role: user
    content: Summarize section 1.
  - role: assistant
    content: Section 1 covers...
  - role: user
    content: Now summarize section 2.
diagnostics:
  previous_message_id: $message_id
YAML

client = anthropic.Anthropic()

SYSTEM = "You are an AI assistant analyzing a large document. <document>...</document>"

# Turn 1: opt in with previous_message_id=None
r1 = client.beta.messages.create(
    model="claude-opus-5-5",
    max_tokens=1024,
    cache_control={"type": "ephemeral"},
    system=SYSTEM,
    messages=[{"role": "user", "content": "Summarize section 1."}],
    diagnostics={"previous_message_id": None},
    betas=["cache-diagnosis-2026-04-07"],
)

# Turn 2: reference the previous response id
r2 = client.beta.messages.create(
    model="claude-opus-5-5",
    max_tokens=1024,
    cache_control={"type": "ephemeral"},
    system=SYSTEM,
    messages=[
        {"role": "user", "content": "Summarize section 1."},
        {"role": "assistant", "content": r1.content},
        {"role": "user", "content": "Now summarize section 2."},
    ],
    diagnostics={"previous_message_id": r1.id},
    betas=["cache-diagnosis-2026-04-07"],
)

diagnostics = r2.diagnostics
if diagnostics is None:
    print("No divergence detected.")
elif diagnostics.cache_miss_reason is None:
    print("Comparison still pending.")
else:
    print(f"cache_miss_reason: {diagnostics.cache_miss_reason.type}")

const client = new Anthropic();

const SYSTEM = "You are an AI assistant analyzing a large document. <document>...</document>";

// Turn 1: opt in with previous_message_id: null
const r1 = await client.beta.messages.create({
  model: "claude-opus-5-5",
  max_tokens: 1024,
  cache_control: { type: "ephemeral" },
  system: SYSTEM,
  messages: [{ role: "user", content: "Summarize section 1." }],
  diagnostics: { previous_message_id: null },
  betas: ["cache-diagnosis-2026-04-07"]
});

// Turn 2: reference the previous response id
const r2 = await client.beta.messages.create({
  model: "claude-opus-5-5",
  max_tokens: 1024,
  cache_control: { type: "ephemeral" },
  system: SYSTEM,
  messages: [
    { role: "user", content: "Summarize section 1." },
    { role: "assistant", content: r1.content },
    { role: "user", content: "Now summarize section 2." }
  ],
  diagnostics: { previous_message_id: r1.id },
  betas: ["cache-diagnosis-2026-04-07"]
});

if (r2.diagnostics === null) {
  console.log("No divergence detected.");
} else if (r2.diagnostics.cache_miss_reason === null) {
  console.log("Comparison still pending.");
} else {
  console.log(`cache_miss_reason: ${r2.diagnostics.cache_miss_reason.type}`);
}

AnthropicClient client = new();

var system = "You are an AI assistant analyzing a large document. <document>...</document>";

var r1 = await client.Beta.Messages.Create(
    new()
    {
        Model = Messages::Model.ClaudeOpus5_5,
        MaxTokens = 1024,
        CacheControl = new(),
        System = system,
        Messages =
        [
            new() { Role = Role.User, Content = "Summarize section 1." },
        ],
        Diagnostics = new() { PreviousMessageID = null },
        Betas = [AnthropicBeta.CacheDiagnosis2026_04_07],
    }
);

var r2 = await client.Beta.Messages.Create(
    new()
    {
        Model = Messages::Model.ClaudeOpus5_5,
        MaxTokens = 1024,
        CacheControl = new(),
        System = system,
        Messages =
        [
            new() { Role = Role.User, Content = "Summarize section 1." },
            new()
            {
                Role = Role.Assistant,
                Content = r1.Content.Select(block => new BetaContentBlockParam(block.Json)).ToList(),
            },
            new() { Role = Role.User, Content = "Now summarize section 2." },
        ],
        Diagnostics = new() { PreviousMessageID = r1.ID },
        Betas = [AnthropicBeta.CacheDiagnosis2026_04_07],
    }
);

Console.WriteLine(r2.Diagnostics switch
{
    null => "No divergence detected.",
    { CacheMissReason: null } => "Comparison still pending.",
    { CacheMissReason.Type: var type } => $"cache_miss_reason: {type.GetString()}",
});

client := anthropic.NewClient()
ctx := context.Background()

system := []anthropic.BetaTextBlockParam{
	{Text: "You are an AI assistant analyzing a large document. <document>...</document>"},
}

r1, err := client.Beta.Messages.New(ctx, anthropic.BetaMessageNewParams{
	Model:        anthropic.ModelClaudeOpus5_5,
	MaxTokens:    1024,
	CacheControl: anthropic.BetaCacheControlEphemeralParam{},
	System:       system,
	Messages: []anthropic.BetaMessageParam{
		anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock("Summarize section 1.")),
	},
	Diagnostics: anthropic.BetaDiagnosticsParam{
		PreviousMessageID: param.Null[string](),
	},
	Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCacheDiagnosis2026_04_07},
})
if err != nil {
	panic(err)
}

r2, err := client.Beta.Messages.New(ctx, anthropic.BetaMessageNewParams{
	Model:        anthropic.ModelClaudeOpus5_5,
	MaxTokens:    1024,
	CacheControl: anthropic.BetaCacheControlEphemeralParam{},
	System:       system,
	Messages: []anthropic.BetaMessageParam{
		anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock("Summarize section 1.")),
		r1.ToParam(),
		anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock("Now summarize section 2.")),
	},
	Diagnostics: anthropic.BetaDiagnosticsParam{
		PreviousMessageID: anthropic.String(r1.ID),
	},
	Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCacheDiagnosis2026_04_07},
})
if err != nil {
	panic(err)
}

switch {
case !r2.JSON.Diagnostics.Valid():
	fmt.Println("No divergence detected.")
case !r2.Diagnostics.JSON.CacheMissReason.Valid():
	fmt.Println("Comparison still pending.")
default:
	fmt.Printf("cache_miss_reason: %s\n", r2.Diagnostics.CacheMissReason.Type)
}

var client = AnthropicOkHttpClient.fromEnv();

var system = "You are an AI assistant analyzing a large document. <document>...</document>";

var r1 = client.beta().messages().create(
    MessageCreateParams.builder()
        .model(Model.CLAUDE_OPUS_5_5)
        .maxTokens(1024)
        .cacheControl(BetaCacheControlEphemeral.builder().build())
        .system(system)
        .addUserMessage("Summarize section 1.")
        // Pass null on the first turn to opt in without a prior message to compare.
        .diagnostics(BetaDiagnosticsParam.builder().previousMessageId((String) null).build())
        .addBeta(AnthropicBeta.CACHE_DIAGNOSIS_2026_04_07)
        .build()
);

var r2 = client.beta().messages().create(
    MessageCreateParams.builder()
        .model(Model.CLAUDE_OPUS_5_5)
        .maxTokens(1024)
        .cacheControl(BetaCacheControlEphemeral.builder().build())
        .system(system)
        .addUserMessage("Summarize section 1.")
        .addMessage(r1)
        .addUserMessage("Now summarize section 2.")
        .diagnostics(BetaDiagnosticsParam.builder().previousMessageId(r1.id()).build())
        .addBeta(AnthropicBeta.CACHE_DIAGNOSIS_2026_04_07)
        .build()
);

if (r2.diagnostics().isEmpty()) {
    IO.println("No divergence detected.");
} else if (r2.diagnostics().get().cacheMissReason().isEmpty()) {
    IO.println("Comparison still pending.");
} else {
    var reason = r2.diagnostics().get().cacheMissReason().get();
    // CacheMissReason doesn't expose a typed .type() accessor; read it from the raw JSON.
    @SuppressWarnings("unchecked")
    var json = (Map<String, JsonValue>) reason._json().orElseThrow().asObject().orElseThrow();
    IO.println("cache_miss_reason: " + json.get("type").asStringOrThrow());
}

$client = new Client();

$system = 'You are an AI assistant analyzing a large document. <document>...</document>';

$r1 = $client->beta->messages->create(
    model: Model::CLAUDE_OPUS_5_5,
    maxTokens: 1024,
    cacheControl: new BetaCacheControlEphemeral,
    system: $system,
    messages: [
        ['role' => 'user', 'content' => 'Summarize section 1.'],
    ],
    diagnostics: (new BetaDiagnosticsParam)->withPreviousMessageID(null),
    betas: [AnthropicBeta::CACHE_DIAGNOSIS_2026_04_07],
);

$r2 = $client->beta->messages->create(
    model: Model::CLAUDE_OPUS_5_5,
    maxTokens: 1024,
    cacheControl: new BetaCacheControlEphemeral,
    system: $system,
    messages: [
        ['role' => 'user', 'content' => 'Summarize section 1.'],
        ['role' => 'assistant', 'content' => $r1->content],
        ['role' => 'user', 'content' => 'Now summarize section 2.'],
    ],
    diagnostics: (new BetaDiagnosticsParam)->withPreviousMessageID($r1->id),
    betas: [AnthropicBeta::CACHE_DIAGNOSIS_2026_04_07],
);

echo match (true) {
    $r2->diagnostics === null => "No divergence detected.\n",
    $r2->diagnostics->cacheMissReason === null => "Comparison still pending.\n",
    default => "cache_miss_reason: {$r2->diagnostics->cacheMissReason->type}\n",
};

client = Anthropic::Client.new

SYSTEM = "You are an AI assistant analyzing a large document. <document>...</document>"

r1 = client.beta.messages.create(
  model: :"claude-opus-5-5",
  max_tokens: 1024,
  cache_control: {type: "ephemeral"},
  system_: SYSTEM,
  messages: [
    {role: "user", content: "Summarize section 1."}
  ],
  diagnostics: {previous_message_id: nil},
  betas: ["cache-diagnosis-2026-04-07"]
)

r2 = client.beta.messages.create(
  model: :"claude-opus-5-5",
  max_tokens: 1024,
  cache_control: {type: "ephemeral"},
  system_: SYSTEM,
  messages: [
    {role: "user", content: "Summarize section 1."},
    {role: "assistant", content: r1.content},
    {role: "user", content: "Now summarize section 2."}
  ],
  diagnostics: {previous_message_id: r1.id},
  betas: ["cache-diagnosis-2026-04-07"]
)

case r2.diagnostics
in nil
  puts "No divergence detected."
in {cache_miss_reason: nil}
  puts "Comparison still pending."
in {cache_miss_reason: {type:}}
  puts "cache_miss_reason: #{type}"
end