Sweep 22 Sep 2026 · 17:19Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
One change · api

compaction-on-demand changed

build-with-claude/compaction-on-demand

Nearest release: v2.1.280, published under an hour before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Recorded here
Lines+26added
Lines−25removed
From line 11 where the diff opens
First seen 21 Sep 2026 this site's first read of the page
Recorded edits3to this page, all time

The whole hunk

from line 11, old and new numbered
/
lines
from line 11
1111 - claude-fable-5
1212 - claude-mythos-5
1313 - claude-mythos-preview
14 - claude-opus-5-5
1415 - claude-opus-5
1516 - claude-opus-4-8
1617 - claude-opus-4-7
from line 51
5051 -H "anthropic-beta: compact-2026-09-04" \
5152 -H "content-type: application/json" \
5253 -d '{
53 "model": "claude-opus-5",
54 "model": "claude-opus-5-5",
5455 "max_tokens": 4096,
5556 "messages": [
5657 {"role": "user", "content": "I am building a recipe app. Help me name the main entities in the data model."},
from line 69
6869 
6970 <File filename="request.yaml">
7071 ```yaml
71 model: claude-opus-5
72 model: claude-opus-5-5
7273 # max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
7374 max_tokens: 4096
7475 messages:
from line 103
102103 ]
103104 
104105 response = client.beta.messages.create(
105 model="claude-opus-5",
106 model="claude-opus-5-5",
106107 # max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
107108 max_tokens=4096,
108109 betas=["compact-2026-09-04"],
from line 130
129130 ];
130131 
131132 const response = await client.beta.messages.create({
132 model: "claude-opus-5",
133 model: "claude-opus-5-5",
133134 // max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
134135 max_tokens: 4096,
135136 betas: ["compact-2026-09-04"],
from line 164
163164 
164165 var response = await client.Beta.Messages.Create(new MessageCreateParams
165166 {
166 Model = Model.ClaudeOpus5,
167 Model = Model.ClaudeOpus5_5,
167168 // max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
168169 MaxTokens = 4096,
169170 Betas = [AnthropicBeta.Compact2026_09_04],
from line 188
187188 }
188189 
189190 response, err := client.Beta.Messages.New(context.TODO(), anthropic.BetaMessageNewParams{
190 Model: anthropic.ModelClaudeOpus5,
191 Model: anthropic.ModelClaudeOpus5_5,
191192 // max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
192193 MaxTokens: 4096,
193194 Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCompact2026_09_04},
from line 212
211212 var client = AnthropicOkHttpClient.fromEnv();
212213 
213214 var params = MessageCreateParams.builder()
214 .model(Model.CLAUDE_OPUS_5)
215 .model(Model.CLAUDE_OPUS_5_5)
215216 // max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
216217 .maxTokens(4096)
217218 .addBeta(AnthropicBeta.COMPACT_2026_09_04)
from line 248
247248 ];
248249 
249250 $response = $client->beta->messages->create(
250 model: Model::CLAUDE_OPUS_5,
251 model: Model::CLAUDE_OPUS_5_5,
251252 // max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
252253 maxTokens: 4096,
253254 betas: [AnthropicBeta::COMPACT_2026_09_04],
from line 275
274275 ]
275276 
276277 response = client.beta.messages.create(
277 model: Anthropic::Model::CLAUDE_OPUS_5,
278 model: Anthropic::Model::CLAUDE_OPUS_5_5,
278279 # max_tokens caps the whole call, including any thinking, so allow several thousand tokens.
279280 max_tokens: 4096,
280281 betas: [Anthropic::AnthropicBeta::COMPACT_2026_09_04],
from line 291
290291 "id": "msg_013Zva2CMHLNnXjNJJKqJ2EF",
291292 "type": "message",
292293 "role": "assistant",
293 "model": "claude-opus-5",
294 "model": "claude-opus-5-5",
294295 "content": [
295296 {
296297 "type": "compaction",
from line 320
319320 
320321```json
321322{
322 "model": "claude-opus-5",
323 "model": "claude-opus-5-5",
323324 "max_tokens": 2048,
324325 "messages": [
325326 {
from line 393
392393 for turn, question in enumerate(QUESTIONS, start=1):
393394 history.append({"role": "user", "content": question})
394395 response = client.beta.messages.create(
395 model="claude-opus-5",
396 model="claude-opus-5-5",
396397 max_tokens=8192,
397398 system=SYSTEM,
398399 betas=["compact-2026-09-04"],
from line 405
404405 conversation_tokens = response.usage.input_tokens + response.usage.output_tokens
405406 if conversation_tokens > COMPACT_AT_TOKENS and turn < len(QUESTIONS):
406407 summary = client.beta.messages.create(
407 model="claude-opus-5",
408 model="claude-opus-5-5",
408409 max_tokens=4096,
409410 system=SYSTEM,
410411 betas=["compact-2026-09-04"],
from line 440
439440 const turn = index + 1;
440441 history.push({ role: "user", content: question });
441442 const response = await client.beta.messages.create({
442 model: "claude-opus-5",
443 model: "claude-opus-5-5",
443444 max_tokens: 8192,
444445 system: systemPrompt,
445446 betas: ["compact-2026-09-04"],
from line 452
451452 const conversationTokens = response.usage.input_tokens + response.usage.output_tokens;
452453 if (conversationTokens > compactAtTokens && turn < questions.length) {
453454 const summary = await client.beta.messages.create({
454 model: "claude-opus-5",
455 model: "claude-opus-5-5",
455456 max_tokens: 4096,
456457 system: systemPrompt,
457458 betas: ["compact-2026-09-04"],
from line 497
496497 history.Add(new() { Role = Role.User, Content = question });
497498 var response = await client.Beta.Messages.Create(new MessageCreateParams
498499 {
499 Model = Model.ClaudeOpus5,
500 Model = Model.ClaudeOpus5_5,
500501 MaxTokens = 8192,
501502 System = SystemPrompt,
502503 Betas = [AnthropicBeta.Compact2026_09_04],
from line 515
514515 {
515516 var summary = await client.Beta.Messages.Create(new MessageCreateParams
516517 {
517 Model = Model.ClaudeOpus5,
518 Model = Model.ClaudeOpus5_5,
518519 MaxTokens = 4096,
519520 System = SystemPrompt,
520521 Betas = [AnthropicBeta.Compact2026_09_04],
from line 562
561562 turn := i + 1
562563 history = append(history, anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock(question)))
563564 response, err := client.Beta.Messages.New(ctx, anthropic.BetaMessageNewParams{
564 Model: anthropic.ModelClaudeOpus5,
565 Model: anthropic.ModelClaudeOpus5_5,
565566 MaxTokens: 8192,
566567 System: system,
567568 Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCompact2026_09_04},
from line 577
576577 conversationTokens := response.Usage.InputTokens + response.Usage.OutputTokens
577578 if conversationTokens > compactAtTokens && turn < len(questions) {
578579 summary, err := client.Beta.Messages.New(ctx, anthropic.BetaMessageNewParams{
579 Model: anthropic.ModelClaudeOpus5,
580 Model: anthropic.ModelClaudeOpus5_5,
580581 MaxTokens: 4096,
581582 System: system,
582583 Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCompact2026_09_04},
from line 629
628629 .content(questions.get(turn - 1))
629630 .build());
630631 var params = MessageCreateParams.builder()
631 .model(Model.CLAUDE_OPUS_5)
632 .model(Model.CLAUDE_OPUS_5_5)
632633 .maxTokens(8192)
633634 .system(SYSTEM)
634635 .addBeta(AnthropicBeta.COMPACT_2026_09_04)
from line 642
641642 long conversationTokens = response.usage().inputTokens() + response.usage().outputTokens();
642643 if (conversationTokens > COMPACT_AT_TOKENS && turn < questions.size()) {
643644 var summaryParams = MessageCreateParams.builder()
644 .model(Model.CLAUDE_OPUS_5)
645 .model(Model.CLAUDE_OPUS_5_5)
645646 .maxTokens(4096)
646647 .system(SYSTEM)
647648 .addBeta(AnthropicBeta.COMPACT_2026_09_04)
from line 689
688689 $turn = $index + 1;
689690 $history[] = BetaMessageParam::with(role: Role::USER, content: $question);
690691 $response = $client->beta->messages->create(
691 model: Model::CLAUDE_OPUS_5,
692 model: Model::CLAUDE_OPUS_5_5,
692693 maxTokens: 8192,
693694 system: SYSTEM,
694695 betas: [AnthropicBeta::COMPACT_2026_09_04],
from line 701
700701 $conversationTokens = $response->usage->inputTokens + $response->usage->outputTokens;
701702 if ($conversationTokens > COMPACT_AT_TOKENS && $turn < count($questions)) {
702703 $summary = $client->beta->messages->create(
703 model: Model::CLAUDE_OPUS_5,
704 model: Model::CLAUDE_OPUS_5_5,
704705 maxTokens: 4096,
705706 system: SYSTEM,
706707 betas: [AnthropicBeta::COMPACT_2026_09_04],
from line 738
737738 questions.each.with_index(1) do |question, turn|
738739 history << { role: "user", content: question }
739740 response = client.beta.messages.create(
740 model: Anthropic::Model::CLAUDE_OPUS_5,
741 model: Anthropic::Model::CLAUDE_OPUS_5_5,
741742 max_tokens: 8192,
742743 system_: SYSTEM,
743744 betas: [Anthropic::AnthropicBeta::COMPACT_2026_09_04],
from line 750
749750 conversation_tokens = response.usage.input_tokens + response.usage.output_tokens
750751 if conversation_tokens > COMPACT_AT_TOKENS && turn < questions.length
751752 summary = client.beta.messages.create(
752 model: Anthropic::Model::CLAUDE_OPUS_5,
753 model: Anthropic::Model::CLAUDE_OPUS_5_5,
753754 max_tokens: 4096,
754755 system_: SYSTEM,
755756 betas: [Anthropic::AnthropicBeta::COMPACT_2026_09_04],