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Sweep 06 Nov 2026 · 01:32Z Build v2.1.319 537 read Stable v2.1.311 Latest v2.1.319 Next v2.1.319 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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What has changed since

An entry is only as true as the day it was written.

Flags move on the server after a release ships. Anthropic's own notes land days later and their documentation later still. Sometimes an entry turns out to be wrong and gets corrected by hand. All of that is recorded against the entry it happened to, and this is the whole of it in the order it happened.

Nothing here replaces an entry. Every line links to the page its release published, still saying what that release said, because a correction is added and dated rather than swapped in.

Events22,566dated, and never edited afterwards
Newestthe last time anything moved
Flag readings moved17,208a reading is one sample, for one account
Documentation arrived5,248a docs edit touched an entry's names
WhenEntryWhat happened
v2.1.251tengu_juniper_relay Flag reading movedThe flag server now returns on for tengu_juniper_relay, read as this account.
v2.1.299tengu_glowing_lark Flag reading movedThe flag server now returns on for tengu_glowing_lark, read as this account.
v2.1.299tengu_glowing_lark Flag reading movedThe flag server now returns on for tengu_glowing_lark, read as this account.
v2.1.265tengu_curious_tower_stateless_models Flag reading movedThe flag server now returns "" for tengu_curious_tower_stateless_models, read as this account.
v2.1.246tengu_ticklish_whisper Flag reading movedThe flag server now returns off for tengu_ticklish_whisper, read as this account.
v2.1.282tengu_smooth_chipmunk Flag reading movedThe flag server now returns off for tengu_smooth_chipmunk, read as this account.
v2.1.281tengu_smooth_chipmunk Flag reading movedThe flag server now returns off for tengu_smooth_chipmunk, read as this account.
v2.1.281tengu_smooth_chipmunk Flag reading movedThe flag server now returns off for tengu_smooth_chipmunk, read as this account.
v2.1.269tengu_smooth_chipmunk Flag reading movedThe flag server now returns off for tengu_smooth_chipmunk, read as this account.
v2.1.261tengu_smooth_chipmunk Flag reading movedThe flag server now returns off for tengu_smooth_chipmunk, read as this account.
v2.1.261tengu_smooth_chipmunk Flag reading movedThe flag server now returns off for tengu_smooth_chipmunk, read as this account.
v2.1.281tengu_shimmying_stardust Flag reading movedThe flag server now returns off for tengu_shimmying_stardust, read as this account.
v2.1.273tengu_shimmying_stardust Flag reading movedThe flag server now returns off for tengu_shimmying_stardust, read as this account.
v2.1.273tengu_shimmying_stardust Flag reading movedThe flag server now returns off for tengu_shimmying_stardust, read as this account.
v2.1.299tengu_glowing_lark Flag reading movedThe flag server now returns off for tengu_glowing_lark, read as this account.
v2.1.299tengu_glowing_lark Flag reading movedThe flag server now returns off for tengu_glowing_lark, read as this account.
v2.1.257tengu_elegant_pancake Flag reading movedThe flag server now returns off for tengu_elegant_pancake, read as this account.
v2.1.265tengu_curious_tower_stateless_models Flag reading movedThe flag server now returns "fable-5-1, opus-5, opus-4-8" for tengu_curious_tower_stateless_models, read as this account.
v2.1.248tengu_ccr_no_subscriber_flush_ms Flag reading movedThe flag server now returns null for tengu_ccr_no_subscriber_flush_ms, read as this account.
v2.1.248tengu_ccr_no_subscriber_flush_ms Flag reading movedThe flag server now returns null for tengu_ccr_no_subscriber_flush_ms, read as this account.
v2.1.246tengu_ticklish_whisper Flag reading movedThe flag server now returns on for tengu_ticklish_whisper, read as this account.
v2.1.311tengu_snug_mitten Flag reading movedThe flag server now returns on for tengu_snug_mitten, read as this account.
v2.1.282tengu_smooth_chipmunk Flag reading movedThe flag server now returns on for tengu_smooth_chipmunk, read as this account.
v2.1.281tengu_smooth_chipmunk Flag reading movedThe flag server now returns on for tengu_smooth_chipmunk, read as this account.
v2.1.281tengu_smooth_chipmunk Flag reading movedThe flag server now returns on for tengu_smooth_chipmunk, read as this account.
v2.1.269tengu_smooth_chipmunk Flag reading movedThe flag server now returns on for tengu_smooth_chipmunk, read as this account.
v2.1.261tengu_smooth_chipmunk Flag reading movedThe flag server now returns on for tengu_smooth_chipmunk, read as this account.
v2.1.261tengu_smooth_chipmunk Flag reading movedThe flag server now returns on for tengu_smooth_chipmunk, read as this account.
v2.1.281tengu_shimmying_stardust Flag reading movedThe flag server now returns on for tengu_shimmying_stardust, read as this account.
v2.1.273tengu_shimmying_stardust Flag reading movedThe flag server now returns on for tengu_shimmying_stardust, read as this account.
v2.1.273tengu_shimmying_stardust Flag reading movedThe flag server now returns on for tengu_shimmying_stardust, read as this account.
v2.1.299tengu_glowing_lark Flag reading movedThe flag server now returns on for tengu_glowing_lark, read as this account.
v2.1.299tengu_glowing_lark Flag reading movedThe flag server now returns on for tengu_glowing_lark, read as this account.
v2.1.288tengu_fancy_wand Flag reading movedThe flag server now returns on for tengu_fancy_wand, read as this account.
v2.1.257tengu_elegant_pancake Flag reading movedThe flag server now returns on for tengu_elegant_pancake, read as this account.
v2.1.265tengu_curious_tower_stateless_models Flag reading movedThe flag server now returns "" for tengu_curious_tower_stateless_models, read as this account.
v2.1.248tengu_ccr_no_subscriber_flush_ms Flag reading movedThe flag server now returns 2000 for tengu_ccr_no_subscriber_flush_ms, read as this account.
v2.1.248tengu_ccr_no_subscriber_flush_ms Flag reading movedThe flag server now returns 2000 for tengu_ccr_no_subscriber_flush_ms, read as this account.
v2.1.310haiku Documentation arrivedA small documentation edit on overview touched a line naming haiku after this was published.
the line in the docs

[What’s new in Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/whats-new-haiku-5-5)
v2.1.309--remote Documentation arrivedAnthropic's documentation has since written up --remote, on WARNING: This operation PERMANENTLY deletes the chat, all of its messages,.
the line in the docs

In curl, the `--remote-header-name` (`-J`) option, which normally saves a download under the `Content-Disposition` file name, does not read the `filename*` form, so name the saved file yourself with `--output`. In a script, take the name f…
v2.1.310opus Documentation arrivedA small documentation edit on intro touched a line naming opus after this was published.
the line in the docs

If you’re unsure which model to use, start with [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview) for most workloads. Use [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) for d…
v2.1.310fable Documentation arrivedA small documentation edit on intro touched a line naming fable after this was published.
the line in the docs

If you’re unsure which model to use, start with [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview) for most workloads. Use [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) for d…
v2.1.310ANTHROPIC_BASE_URL Documentation arrivedAnthropic's documentation has since written up ANTHROPIC_BASE_URL, on Before.
the line in the docs

If `--base-url` or `ANTHROPIC_BASE_URL` points `ant` at a proxy or gateway that reads `X-Api-Key`, change it to read the key from `Authorization`. `ant` has no flag or environment variable for adding a header of your own, so it can’t send …
v2.1.309file_upload Documentation arrivedAnthropic's documentation has since written up file_upload, on browser-use-sdk.
the line in the docs

`file_upload` is off by default. With no `file_policy` (typescript: `filePolicy`), the SDK refuses every upload that gives a path or a [document ID](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool#upload-file…
v2.1.309file_upload Documentation arrivedAnthropic's documentation has since written up file_upload, on browser-use-sdk.
the line in the docs

`file_upload` is off by default. With no `file_policy` (typescript: `filePolicy`), the SDK refuses every upload that gives a path or a [document ID](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool#upload-file…
v2.1.311tengu_wobbly_petal Flag reading movedThe flag server now returns null for tengu_wobbly_petal, read as this account.
v2.1.206tengu_umber_kestrel Flag reading movedThe flag server now returns off for tengu_umber_kestrel, read as this account.
v2.1.239tengu_toasty_breeze Flag reading movedThe flag server now returns {"enabled":false,"version":0} for tengu_toasty_breeze, read as this account.
v2.1.239tengu_toasty_breeze Flag reading movedThe flag server now returns {"enabled":false,"version":0} for tengu_toasty_breeze, read as this account.
v2.1.307tengu_sunny_locket Flag reading movedThe flag server now returns {"mode":"off"} for tengu_sunny_locket, read as this account.
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