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-background changed

build-with-claude/compaction-background

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+13added
Lines−12removed
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 93
9293 
9394 history.append({"role": "user", "content": question})
9495 response = client.beta.messages.create(
95 model="claude-opus-5",
96 model="claude-opus-5-5",
9697 max_tokens=8192,
9798 system=SYSTEM,
9899 betas=["compact-2026-09-04"],
from line 111
110111 sent = len(history)
111112 pending = executor.submit(
112113 client.beta.messages.create,
113 model="claude-opus-5",
114 model="claude-opus-5-5",
114115 max_tokens=4096,
115116 system=SYSTEM,
116117 betas=["compact-2026-09-04"],
from line 171
170171 
171172 history.push({ role: "user", content: question });
172173 const response = await client.beta.messages.create({
173 model: "claude-opus-5",
174 model: "claude-opus-5-5",
174175 max_tokens: 8192,
175176 system: systemPrompt,
176177 betas: ["compact-2026-09-04"],
from line 184
183184 if (conversationTokens > compactAtTokens && turn < questions.length && !pending) {
184185 sent = history.length;
185186 pending = client.beta.messages.create({
186 model: "claude-opus-5",
187 model: "claude-opus-5-5",
187188 max_tokens: 4096,
188189 system: systemPrompt,
189190 betas: ["compact-2026-09-04"],
from line 262
261262 history.Add(new() { Role = Role.User, Content = question });
262263 var response = await client.Beta.Messages.Create(new MessageCreateParams
263264 {
264 Model = Model.ClaudeOpus5,
265 Model = Model.ClaudeOpus5_5,
265266 MaxTokens = 8192,
266267 System = SystemPrompt,
267268 Betas = [AnthropicBeta.Compact2026_09_04],
from line 281
280281 sent = history.Count;
281282 pending = client.Beta.Messages.Create(new MessageCreateParams
282283 {
283 Model = Model.ClaudeOpus5,
284 Model = Model.ClaudeOpus5_5,
284285 MaxTokens = 4096,
285286 System = SystemPrompt,
286287 Betas = [AnthropicBeta.Compact2026_09_04],
from line 341
340341 
341342 history = append(history, anthropic.NewBetaUserMessage(anthropic.NewBetaTextBlock(question)))
342343 response, err := client.Beta.Messages.New(ctx, anthropic.BetaMessageNewParams{
343 Model: anthropic.ModelClaudeOpus5,
344 Model: anthropic.ModelClaudeOpus5_5,
344345 MaxTokens: 8192,
345346 System: system,
346347 Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCompact2026_09_04},
from line 359
358359 pending = make(chan *anthropic.BetaMessage, 1)
359360 go func(messages []anthropic.BetaMessageParam, result chan<- *anthropic.BetaMessage) {
360361 summary, err := client.Beta.Messages.New(ctx, anthropic.BetaMessageNewParams{
361 Model: anthropic.ModelClaudeOpus5,
362 Model: anthropic.ModelClaudeOpus5_5,
362363 MaxTokens: 4096,
363364 System: system,
364365 Betas: []anthropic.AnthropicBeta{anthropic.AnthropicBetaCompact2026_09_04},
from line 432
431432 .content(questions.get(turn - 1))
432433 .build());
433434 var params = MessageCreateParams.builder()
434 .model(Model.CLAUDE_OPUS_5)
435 .model(Model.CLAUDE_OPUS_5_5)
435436 .maxTokens(8192)
436437 .system(SYSTEM)
437438 .addBeta(AnthropicBeta.COMPACT_2026_09_04)
from line 446
445446 if (conversationTokens > COMPACT_AT_TOKENS && turn < questions.size() && pending == null) {
446447 sent = history.size();
447448 var summaryParams = MessageCreateParams.builder()
448 .model(Model.CLAUDE_OPUS_5)
449 .model(Model.CLAUDE_OPUS_5_5)
449450 .maxTokens(4096)
450451 .system(SYSTEM)
451452 .addBeta(AnthropicBeta.COMPACT_2026_09_04)
from line 502
501502 
502503 history << { role: "user", content: question }
503504 response = client.beta.messages.create(
504 model: Anthropic::Model::CLAUDE_OPUS_5,
505 model: Anthropic::Model::CLAUDE_OPUS_5_5,
505506 max_tokens: 8192,
506507 system_: SYSTEM,
507508 betas: [Anthropic::AnthropicBeta::COMPACT_2026_09_04],
from line 516
515516 sent = history.length
516517 pending = Thread.new(history.dup) do |snapshot|
517518 client.beta.messages.create(
518 model: Anthropic::Model::CLAUDE_OPUS_5,
519 model: Anthropic::Model::CLAUDE_OPUS_5_5,
519520 max_tokens: 4096,
520521 system_: SYSTEM,
521522 betas: [Anthropic::AnthropicBeta::COMPACT_2026_09_04],