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Releases

agents@0.23.0

Minor Changes

• #2193 87bd594 Thanks @mattzcarey! - Extract facet ("sub-agent") machinery into packages/agents/src/dynamic-agents/, add the this.dynamicAgents capability facade, and reposition facets as an isolation primitive rather than the recommended way to model many chat sessions.

  Agent's facet routing, WebSocket forwarding, virtual connections, and registry (~2,400 of index.ts's ~12,150 lines) move into a dedicated module registered as a Lifecycle capability (capabilityId: "dynamic-agents"); its hot paths stay composition-root wired since the capability-runner hook contract can't express request-rewrite-and-continue or post-claim WebSocket forwarding. No wire- or storage-visible identifier changes.

  The public surface gains this.dynamicAgents.{get,abort,delete,has,list} plus the DynamicAgentClass and DynamicAgentStub type names. SubAgentClass and SubAgentStub remain as compatibility aliases. subAgent() / abortSubAgent() / deleteSubAgent() / hasSubAgent() / listSubAgents() are unchanged in behavior and now delegate to the same capability — @deprecated in place, not removed. /sub/ URLs, useAgent({ sub }), parentAgent(), and onBeforeSubAgent are untouched.

  docs/agents/sub-agents.md is rewritten: verified workerd facet semantics (separate isolate, own SQLite, no independent alarms, bounded nesting depth, machine-pinned tree), a corrected claim about WebSocket frame forwarding (every frame wakes the root parent — it was never true that frames go directly to the child post-upgrade), and an explicit decision rule for facets vs. independent Durable Objects. Two new examples: examples/next/dynamic-agents (a supervisor running user-submitted Durable Object code as facets via Worker Loader — what facets are for) and examples/next/chats (one top-level DO per chat plus a per-user push-based index — the recommended many-chats pattern), both with a React + Vite UI and workers-pool tests.

• #2175 8ffb3ad Thanks @mattzcarey! - Lifecycle owns a durable job queue, driven as an alarm event loop.

  The thing in the queue is a job: a serialisable callback address — the
  owning capability plus a function name — with a due time and a payload.
  Capabilities and the host push jobs through the scoped jobs surface;
  Lifecycle drives due jobs in timestamp order when the alarm fires, owns
  dispatch retries and platform-failure deferral, arms a deadman pre-alarm
  before driving so an isolate death mid-drive still wakes the object, and
  derives the physical alarm purely from queue state (queue mutations re-arm
  automatically; an exclusive job suppresses ordinary candidates).

  class Cleanup extends LifecycleCapability {
    async scheduleSweep(time: number) {
      await this.lifecycle.jobs.push({ id: "sweep", fn: "sweep", time });
    }
    onJob({ job }: LifecycleJobContext) {
      // drive result: nothing = complete, { rescheduleAt } = suspend,
      // "yield" = leave due and wake again immediately
    }
  }

  The pull-based alarm-contribution model is removed: capability
  getNextAlarm()/onAlarm(), host getNextAlarm(),
  LifecycleServices.alarms (rearm/disabled), and AlarmContribution
  are gone. Host onAlarm() remains and runs once per alarm invocation
  after due jobs are driven. Terminal application failures reach the
  owner's onJobError(), whose drive result decides advancement.

  The alarm memory-limit circuit breaker (#1825) moves from Agent.alarm()
  into the Lifecycle event loop, targeting the exact executing job; Agent
  contributes domain policy through the new onAlarmMemoryLimit() host
  hook, and Scheduler's __DO_NOT_USE_WILL_BREAK__handleAlarmMemoryLimit
  escape hatch is gone. After recording a strike the breaker now finishes by
  resetting the isolate with ctx.abort(reason, { retryAlarm: false })
  (retry of the handled alarm suppressed; the backoff alarm owns the next
  wake), and Agent.destroy() uses the same no-retry abort so a completed
  teardown's alarm cannot be retried into a fresh constructor that recreates
  the deleted schema.

  Scheduler keeps its entire public API and loses its storage and due-row
  loop: a schedule is one job whose fn is the callback name, and interval
  schedules are single-flight jobs. Existing cf_agents_schedules rows are
  migrated into the cf_agents_jobs queue on startup and the legacy table
  is dropped. Agent's public scheduling and keepAlive() APIs are
  unchanged; its keep-alive, fiber-recovery/facet housekeeping, and
  deferred-destroy wakes are now host jobs, and Think's
  workflow-notification wake replaces the removed _getExtensionAlarm().

• #2198 99e5e2e Thanks @mattzcarey! - Add RoutedAgents (agents/routing), a Lifecycle capability that codifies the "user hub with one Durable Object per chat" topology: an owning Agent keeps a durable catalog of independent top-level Agents and routes to them by public ID.

  class UserAgent extends Agent<Env> {
    readonly chats = new RoutedAgents<ChatAgent, { title: string }>({
      namespace: this.env.ChatAgent,
      route: "chats",
    });
  
    constructor(ctx: DurableObjectState, env: Env) {
      super(ctx, env);
      this.lifecycle.use(this.chats);
    }
  }

  create(), list(), and setMetadata() never wake a target; get() returns an initialized typed stub; delete() hides the entry, condemns the target through Agent's deferred teardown, then drops the row, so a failed call is retryable and a clean teardown never surfaces as an abort error. Requests and WebSocket upgrades under /agents/user-agent/{user}/chats/{id} are forwarded to the target with the suffix preserved, and the target owns the upgraded socket, so chat frames never wake the user hub. Physical Durable Object names are opaque UUIDs held only in the catalog. create() returns the same JSON round-trip of metadata that list() does, and list() breaks equal-timestamp ties by write order rather than by the random entry ID — derived from a MAX(seq) read of the route's own entries each write, a deliberate trade for a route sized like one owner's catalog: DO SQLite bills ~1000 writes for the cost of 1000 reads, so this is cheaper than a maintained counter row (or an index on seq, which would cost a write on every call too) until a route holds several thousand entries.

  Destroying the hub retries condemning every remaining entry (active or still deleting) before its own storage is wiped — this is best-effort, not a durability guarantee: the platform wipes the hub's storage right after disposal regardless of outcome, so a target still unreachable after retries is orphaned, with no catalog row left to retry from later. That tradeoff is documented on the class and in the docs.

  Two documented sharp edges: pick a route that can't collide with the hub's own path segments (a coincidental match with no active entry behind it 404s instead of reaching the hub), and a routed suffix can't address a target's own dynamic agents — Agent.fetch() resolves a /sub/{class}/{name} marker against the hub's exported classes before this capability ever sees the request, so it is served as a facet of the hub instead of being forwarded. Both are called out on the class and in the docs; the second is pinned by a regression test.

  examples/next/chats is rebuilt on RoutedAgents: the hub creates, lists, searches, and deletes chats through the capability, the browser reaches each chat through the hub's route, a failed init() handshake rolls back the catalog entry instead of leaving an ownerless chat, malformed message bodies get a 400 instead of an uncaught exception, and pushed activity is fenced by each message's own strictly-increasing ordinal (not a wall-clock timestamp, which can tie within a millisecond and silently discard a genuinely newer push) inside blockConcurrencyWhile, so neither a delayed push nor two concurrent ones can overwrite one that already landed.

  Lifecycle.use() accepts { fallback: true } to dispatch a capability after every non-fallback one regardless of installation order. Agent installs its WebSockets capability as a fallback, so middleware a subclass installs from its constructor runs before the upgrade catch-all.

• #2196 ec93caf Thanks @mattzcarey! - Add the experimental agents/sessions Lifecycle capability and the agents/context module.

  Sessions owns durable conversation storage: a tree of messages with branches and compaction overlays, streamed and byte-budgeted reads, and full-text search whose index is built by the first search() call. Every table is WITHOUT ROWID with no secondary index, so a text append bills one row on an object that has never searched.

  Sessions stores MESSAGES; it is not a file store. A message rides in one SQLite row until its serialized JSON exceeds the 1.5 MiB row budget, and a message larger than that is split across continuation rows in cf_agents_session_message_chunks and reassembled on read. Nothing is truncated and nothing is too large to store, so there is no size error to catch and nothing to configure. Slices are cut on UTF-8 byte boundaries and never inside a surrogate pair.

  Splitting is not a way to shrink the database: continuation rows live in the same Durable Object as the message, inside the same 10 GB. Sessions imposes no upper bound on a single message, so appendMessage(msg, { source: "client" }) sanitizes and strips reserved metadata but does not limit size; bounding untrusted input is the application's job. An application that handles files should keep them in a file store and put a reference in the message, as Think does with its Workspace.

  A byte budget bounds hydrated memory rather than the first slice: getRecentHistory() charges each row its full stored size, continuation rows and attachments included.

  Prompt context moves out of conversation storage into agents/context: ContextBlocks, the frozen system prompt, AgentContextProvider, AgentSearchProvider, and the skill providers. The Session handle stores messages and nothing else.

  Breaking: the experimental memory stack is removed. The agents/experimental/memory/session and agents/experimental/memory/utils subpaths no longer exist, taking Session.create(), SessionManager, PostgresSessionProvider, PostgresContextProvider, PostgresSearchProvider, R2SkillProvider, and the SessionProvider interface with them. Replacements:

  • Session.create(this).withContext(...) → install new Sessions() on the Lifecycle and declare blocks with new ContextBlocks([...]) from agents/context.
  • createCompactFunction, truncateOlderMessages, and the token estimators → agents/sessions and agents/chat.
  • AgentSearchProvider, AgentContextProvider → agents/context.
  • SessionManager → one Sessions capability holds many sessions by id; a user-facing conversation directory belongs to a parent or router Durable Object.
  • Postgres providers have no replacement; Sessions is Durable Object SQLite only.

  Legacy assistant_* tables are lifted and dropped. On the first wake of a Sessions-backed object, assistant_messages and assistant_compactions are copied in SQL, verified row by row, and dropped; assistant_sessions and assistant_fts are dropped. A source whose rows do not all verify is left in place with a session:migration:incomplete event and the schema version is not stamped, so the lift retries on a later start. There are no tombstone copies, so rolling back after a migration loses that object's conversation.

  Also add Computer and legacy Shell projection to SkillRegistry so Agent Skills can be read and edited as workspace files without making Workspace own conversation data.

• #2190 58c586a Thanks @mattzcarey! - Make the alarm memory-limit circuit breaker (#1825) a self-contained
  Lifecycle concern instead of an Agent-mediated one.

  Recovery-loop membership is now a property of the job row
  (LifecycleJobPushOptions.recoveryLoop): flagged jobs are backed off by
  the breaker on a strike and purged when it seals at the strike budget,
  without disturbing unrelated rows — a recovery schedule can no longer
  silently escape the breaker. The public ScheduleOptions vocabulary is
  unchanged: schedules only shape future work, and chat recovery reaches the
  flag through internal scaffolding (RecoveryLoopScheduleOptions) retained
  only for legacy rows and routed dynamic agents. Root recovery moves to Tasks;
  the scaffolding can be deleted when Tasks supports routed child wakes.
  Capabilities can react to a strike through the new optional onMemoryLimit
  hook, hosts through onAlarmMemoryLimit, and the context identifies the job
  that was executing when one exists. The strike budget is real Lifecycle
  configuration (Lifecycle.install(host, { maxAlarmMemoryLimitStrikes }))
  rather than a composition-root side channel. Until Tasks supports routed
  child wakes, a sealed recovery schedule also forwards the seal to its owning
  dynamic agent so a chat child under a plain Agent root persists its exhausted
  incident and terminal notification.

  Removed accordingly: Agent.onAlarmMemoryLimit's policy relay, the
  _cf_recoveryAlarmCallbacks template hook, Scheduler.applyMemoryLimitPolicy,
  and
  setLifecycleAlarmMemoryLimitStrikes. AIChatAgent and Think flag their
  routed recovery fallback via chatRecoverySchedulePolicy and seal in-flight
  incidents from their own protected onAlarmMemoryLimit hooks; both now
  require agents >= 0.23.0 from the pending release batch (they consume its
  new agents/chat recovery exports and no longer implement the old
  template-method breaker hooks). Agent retains a
  sealed-only call to _cf_sealMemoryLimitedRecovery so already-published chat
  packages whose peer ranges accept agents 0.23 keep terminal notifications;
  that fallback carries no callback-name or queue policy.

• #2169 b12dc0b Thanks @mattzcarey! - Move WebSockets out of Lifecycle into the opt-in WebSockets
  capability, with callables served from an RpcTarget.

  Lifecycle no longer models WebSockets — many hosts never use sockets.
  Hosts that want connections install the capability, which owns the
  subsystem end to end:

  new WebSockets({
    handlers: { onConnect, onMessage, onClose },
    callables: new RoomCallables(),
  });

  The capability claims WebSocket upgrades, accepts hibernating sockets,
  dispatches handlers inside the host invocation boundary, reciprocates
  close handshakes, closes owned connections on host destruction, and
  answers getConnections()/getConnection(). Without it installed,
  upgrades are declined.

  callables exposes an RpcTarget's prototype methods to remote
  callers over a Cap'n Web session (?__agents_rpc=capnweb), with native
  ReadableStream streaming. Agent adds no new surface for this: its
  @callable()-decorated methods are its interface, served on every wire
  — natively over the legacy JSON RPC protocol and, through the
  decorator-derived target, over the Cap'n Web endpoint. There is no
  separate browser client either: useAgent().stub/call reach the
  same interface, and a plain host's endpoint is one
  newWebSocketRpcSession(new WebSocket(callablesRpcUrl(url))) away.

  Agent installs the capability itself, so its onConnect/onMessage/
  onClose/onError/getConnectionTags overrides and connection APIs
  behave exactly as before (same wire, same hibernation attachment
  format). The Lifecycle host contract drops the WebSocket hooks and
  Lifecycle's getConnections/getConnection/broadcast are removed.

  Lifecycle keeps only generic platform pass-throughs —
  onWebSocketUpgrade plus onWebSocketMessage/Close/Error for
  capability-owned hibernation wakes — and LifecycleServices gains a
  narrow sockets surface (accept/get) and a connection/request scope on
  runInHostContext. The capability interaction contract (three
  channels: hooks, services, composition-root apertures) is now
  documented on DurableObjectCapability.

Patch Changes

• #2173 71ce28a Thanks @mattzcarey! - Define the Lifecycle job dispatch contract. Job ids are now scoped to their
  owning capability: a cross-owner id collision throws instead of silently
  replacing the other owner's job. A same-id push() or reschedule() made
  while a job is dispatching supersedes the returned drive result, so a wake
  pushed mid-drive can no longer be lost — and each due job is refetched
  before dispatch, so a job replaced earlier in the same alarm cycle is
  skipped instead of dispatched from its stale snapshot. A dispatch that
  outlives its job's
  hung timeout logs a warning and emits job:slow_dispatch telemetry —
  onJob must stay bounded and detach unbounded work.

• #2194 6da4c44 Thanks @mattzcarey! - Run root-agent chat recovery continuations as chained Tasks instead of schedule rows. Initial recovery attempts deduplicate by incident, delayed retries use durable Task sleeps, and platform failures replay through Task claims. AI Chat and Think share one reserved recovery definition and preserve their existing bounded callback handoff behavior: a failure before handoff stays with the current queue execution, while a detached post-handoff platform failure enqueues exactly one replacement.

  Tasks now propagate condemned-isolate failures out of journaled steps and apply alarm memory-limit backoff and sealing to the run whose wake struck — claim stripped and deadline pushed, so startup reconciliation cannot resurrect it and the reclaim still sees an interrupted attempt. Task wake jobs are pushed with a single dispatch attempt so a platform failure rejects the alarm instead of being retried into a silent reschedule of the still-claimed run. Lifecycle gains trackAlarmWork(): work a job hands off at a bounded return stays inside that alarm's memory-limit breaker domain after the alarm returns, so other jobs stay live while a memory reset from the handoff still records a strike — one strike per reset however many flows observe it — and strikes clear only once no handed-off work is outstanding and the last of it settled clean. retain: false now removes failed and cancelled runs as well as completed runs, releasing journals and idempotency keys after every terminal outcome. Routed dynamic agents temporarily retain the root-owned schedule transport until Tasks supports routed child wakes.

  AI Chat and Think require agents >=0.23.0, the pending release batch containing the shared recovery Task definition and internal enqueue support.

• #2173 71ce28a Thanks @mattzcarey! - Replatform chat's resumable streams onto the agents/streams capability.

  ResumableStream is now a thin adapter over Streams: chat's in-flight turn output lives in the shared durable chunk log (cf_agents_streams / cf_agents_stream_chunks), packed ~10 wire chunks per stored segment for write economy, with completion/error mapped onto stream settlement and retention keyed off the stream row's updated_at (sweeps no longer scan the chunk table). Existing cf_ai_chat_stream_* tables migrate wholesale — including an in-flight stream — on first construction after upgrade, then are dropped. AIChatAgent and Think expose the backing capability as readonly streams, so any streams.read() consumer on the same Durable Object can observe chat streams. The chat wire protocol, replay handshake, and recovery behavior are unchanged.

• #2191 b40bc5b Thanks @mattzcarey! - Cut storage row writes across Streams, the chat adapter, and Tasks — the streaming hot path now writes exactly what the pre-capability chat pattern wrote.

  Streams: the append fence is a read instead of a guarded UPDATE (a Durable Object executes one synchronous block at a time, so state-check + tail-read + INSERT is exactly as atomic), removing one stream-row write per append. The stream row is written only at open and settle; settlement stamps the final cursor, and live cursors/liveness derive from the chunk log's tail. readBatches termination and the reader liveness checks moved to narrow reads.

  Chat adapter: the retention sweep decides abandonment in two phases (coarse row cutoff, then one indexed chunk-tail read per candidate) so an actively appending stream is never swept; the legacy migration imports rows complete (final count and last-activity stamped up front, chunk imports are bare INSERTs — 1+N writes instead of 1+2N); destroy() no longer flushes chunks it deletes in the same call; the cleanup alarm no longer scans the table twice; dead _segmentIndex state removed.

  Tasks: claim refreshes amortize to one row write per half claim-slack of wall time instead of one per step; already-elapsed sleeps journal born-completed in one INSERT; duplicate status messages skip their write; startup reconcile skips job-queue upserts that already match; a parked-run cancel settles in one row write; settle paths only re-sync the wake mirror when their write actually landed.

  Replay memory is bounded: the chat adapter's chunk replay iterates the stored log in pages (a generator over paged reads) instead of materializing the whole turn per reconnecting client.

  Schema: the hot-write capability tables (stream chunks, task runs, task steps, jobs — none released) are now WITHOUT ROWID. Cloudflare bills index maintenance as rows written, and an ordinary rowid table's PRIMARY KEY is a hidden UNIQUE index — so every chunk append was billing 2 rows despite being one table write. WITHOUT ROWID makes it exactly 1. The stream metadata table deliberately stays a rowid table: rowid is the insertion-order tiebreak that keeps newest-first deterministic for same-millisecond rows, at one billed row per stream open. The task runs table also drops its (state, next_at) index, which taxed every claim/refresh/settle write to speed one startup scan.

  The in-suite storage-ops benchmark now pins adapter/legacy write parity exactly (12 table rows per 100-chunk turn, ~8.5× under naive per-chunk appends), models the two-phase sweep, and a write-accounting test pins the billed model per statement (a 100-chunk turn bills 14 rows vs the legacy schema's 33).

• #2173 71ce28a Thanks @mattzcarey! - Add agents/streams: durable incremental output as a Lifecycle capability (experimental).

  One Streams instance per Durable Object owns an ordered, durable chunk log per stream with a monotonic cursor: open() (idempotent on the id), synchronous durable append() that wakes live readers, close()/error() settlement, replay-then-tail read({ from, signal }) plus its batched form readBatches({ from, signal, batchSize, onUpToDate }) (arrays per replay slice and per live-tail wakeup, with a caught-up-to-tail signal), indexed non-unique tags for find-the-latest-stream-of-an-operation lookups (open(id, { tag }) / list({ tag })), sseResponse() for one-call SSE serving with native Last-Event-ID resume and up-to-date/done/error control events, and status() reporting state, cursor, and last activity. Reads are independent of producer liveness; the capability needs no alarm, so it also works on facets.

  Streams is the incremental-output half of the pattern the Tasks migration validated, composed without coupling: a task step appends to a stream and checkpoints { streamId, cursor }, and its recover callback reads streams.status() as durable interruption evidence — proven across a real SIGKILL by the e2e suite, where recovery finalizes the stream at exactly the chunks that survived. Design record: design/rfc-streams.md.

• #2196 ec93caf Thanks @mattzcarey! - Keep attachments out of the message row.

  A part that declares a non-text media type and carries its bytes inline is now stored separately, addressed by its SHA-256, and put back verbatim on read. The message keeps a pointer and its mediaType, so a round trip is exact and a message row stays small however large its payloads are. This is invisible: there is no pointer-mode read.

  The rule is typed rather than sized: an image is extracted at any size, and text is never extracted at any size — long prose still splits across continuation rows. The two mechanisms are independent, so media leaves before the row is measured and a message carrying a large image usually has no continuation rows at all.

  Payload lifetime is derived from message references; the bytes go when the last reference does. Identical payloads store once, which makes a retried write free.

  getRecentHistory() loses its minRecentMessages argument. The byte budget is now a hard ceiling: a message-count floor admitted rows whatever their size, so a window of media-heavy messages could hydrate far past the limit meant to bound it. The newest message is always returned.

  Also fixes two migration faults that could lose data: AIChatAgent dropped its legacy table when rows were merely accounted for rather than imported, deleting any row that failed to parse; and Sessions stamped its schema version even when a legacy lift was incomplete, so it never retried. Both lifts are idempotent, so the source now survives until every row has actually landed.

  appendMessage returns the same message whether it inserted or found a duplicate, and dispatches its append event before any auto-compaction runs, so a cache mirror never misses the row that triggered a compaction. A change-feed listener that throws is reported through the session:error capability event instead of rejecting the write it was told about.

• #2173 71ce28a Thanks @mattzcarey! - Add agents/tasks: durable, replayable background execution as a Lifecycle capability (experimental).

  One Tasks instance per Durable Object owns any number of named Task definitions declared in its constructor (new Tasks({ definitions: {...} }), mirroring the Scheduler's callbacks map), so the registry is rebuilt on every wake and recovery of in-flight runs is correct by construction. Runs start with the typed tasks.run(name, input, options), and tasks.handle(name) gives a typed lens scoped to one definition. A run survives process loss and deployments by replaying its handler from the top: completed step.do() steps return journaled results, step.sleep() / step.sleepUntil() consult persisted deadlines, and execution continues from the first unfinished step under generation fencing. Steps carry per-attempt retry and timeout policy, stable idempotency keys for external deduplication, and step.status() progress with a replay live gate that never re-publishes old progress as new.

  There is no separate recovery mode: an unclean interruption replays the handler on the next wake, and handlers make replay safe with step idempotency keys for external writes and durable evidence (a stream's cursor, a rows-written count) read at the top of the work. The interrupted step is first-class evidence: step.interrupted is { name, attempt } on a replay after process loss (null on clean attempts), and a task:attempt:interrupted event carries the same step. Clean step failures are not interruptions; the retry policy owns them.

  Agent installs the capability automatically as experimental this.tasks, with subclass definitions declared on the overridable taskDefinitions field and framework-internal definitions attached through a composition-root aperture. The internal chat frameworks now run on it: Think and AIChatAgent chat turns and Think's messenger replies each execute as a journaled step with stash() persisted in host storage, and a replay whose live closure is gone branches into the unchanged ChatRecoveryEngine (and messenger recovery) on durable evidence. The legacy runFiber()/startFiber() APIs are unchanged and still recovered by their own scan; facet-hosted turns stay on the legacy engine until routed Fibers land.

  Runs are durably accepted (tasks.run() returns a receipt; idempotency keys join existing runs), inspectable (get, getByIdempotencyKey, list), cooperatively cancellable, and retained until deleted. The capability stores run deadlines in its own tables and mirrors each non-terminal run as one job in the Lifecycle work queue (never touching the physical alarm), so it composes with the Scheduler and other capabilities on one shared, queue-derived alarm. Design record: design/rfc-fibers.md (shipped under the name Tasks).

@cloudflare/ai-chat@0.12.0

Minor Changes

• #2196 ec93caf Thanks @mattzcarey! - Store AIChatAgent messages through agents/sessions while preserving the mutable messages array, destructive regeneration, retention, broadcasts, and v4 message conversion.

  Migration on first wake, no rollback. Existing cf_ai_chat_agent_messages rows are imported once into a linear Sessions chain. The old table is dropped only after every row imported; a row that fails to parse keeps the table in place so it stays recoverable, and the import retries on the next start. Once an object has migrated, rolling back to the previous release leaves it with an empty conversation. Rolling forward again is safe.

  this.messages is empty until onStart. Boot no longer loads the transcript synchronously in the constructor. The legacy lift and a single bounded hydration run in onStart, so a subclass that read this.messages in its constructor now sees []; read it from onStart or later. The array is then mirrored from the Sessions change feed.

  hydrationByteBudget (32 MiB) bounds wake-time hydration. maxPersistedMessages counts stored rows rather than the hydrated window, so retention trims the oldest stored messages even when the transcript is larger than the budget. get-messages streams its response instead of serializing the whole transcript; clients calling .json() on it are unaffected.

  There is nothing to configure about how a message is stored: a message too large for one SQLite row is split across continuation rows and reassembled on read, and a stored row is exactly what the write returned.

Patch Changes

• #2194 6da4c44 Thanks @mattzcarey! - Run root-agent chat recovery continuations as chained Tasks instead of schedule rows. Initial recovery attempts deduplicate by incident, delayed retries use durable Task sleeps, and platform failures replay through Task claims. AI Chat and Think share one reserved recovery definition and preserve their existing bounded callback handoff behavior: a failure before handoff stays with the current queue execution, while a detached post-handoff platform failure enqueues exactly one replacement.

  Tasks now propagate condemned-isolate failures out of journaled steps and apply alarm memory-limit backoff and sealing to the run whose wake struck — claim stripped and deadline pushed, so startup reconciliation cannot resurrect it and the reclaim still sees an interrupted attempt. Task wake jobs are pushed with a single dispatch attempt so a platform failure rejects the alarm instead of being retried into a silent reschedule of the still-claimed run. Lifecycle gains trackAlarmWork(): work a job hands off at a bounded return stays inside that alarm's memory-limit breaker domain after the alarm returns, so other jobs stay live while a memory reset from the handoff still records a strike — one strike per reset however many flows observe it — and strikes clear only once no handed-off work is outstanding and the last of it settled clean. retain: false now removes failed and cancelled runs as well as completed runs, releasing journals and idempotency keys after every terminal outcome. Routed dynamic agents temporarily retain the root-owned schedule transport until Tasks supports routed child wakes.

  AI Chat and Think require agents >=0.23.0, the pending release batch containing the shared recovery Task definition and internal enqueue support.

• #2173 71ce28a Thanks @mattzcarey! - Replatform chat's resumable streams onto the agents/streams capability.

  ResumableStream is now a thin adapter over Streams: chat's in-flight turn output lives in the shared durable chunk log (cf_agents_streams / cf_agents_stream_chunks), packed ~10 wire chunks per stored segment for write economy, with completion/error mapped onto stream settlement and retention keyed off the stream row's updated_at (sweeps no longer scan the chunk table). Existing cf_ai_chat_stream_* tables migrate wholesale — including an in-flight stream — on first construction after upgrade, then are dropped. AIChatAgent and Think expose the backing capability as readonly streams, so any streams.read() consumer on the same Durable Object can observe chat streams. The chat wire protocol, replay handshake, and recovery behavior are unchanged.

• #2190 58c586a Thanks @mattzcarey! - Make the alarm memory-limit circuit breaker (#1825) a self-contained
  Lifecycle concern instead of an Agent-mediated one.

  Recovery-loop membership is now a property of the job row
  (LifecycleJobPushOptions.recoveryLoop): flagged jobs are backed off by
  the breaker on a strike and purged when it seals at the strike budget,
  without disturbing unrelated rows — a recovery schedule can no longer
  silently escape the breaker. The public ScheduleOptions vocabulary is
  unchanged: schedules only shape future work, and chat recovery reaches the
  flag through internal scaffolding (RecoveryLoopScheduleOptions) retained
  only for legacy rows and routed dynamic agents. Root recovery moves to Tasks;
  the scaffolding can be deleted when Tasks supports routed child wakes.
  Capabilities can react to a strike through the new optional onMemoryLimit
  hook, hosts through onAlarmMemoryLimit, and the context identifies the job
  that was executing when one exists. The strike budget is real Lifecycle
  configuration (Lifecycle.install(host, { maxAlarmMemoryLimitStrikes }))
  rather than a composition-root side channel. Until Tasks supports routed
  child wakes, a sealed recovery schedule also forwards the seal to its owning
  dynamic agent so a chat child under a plain Agent root persists its exhausted
  incident and terminal notification.

  Removed accordingly: Agent.onAlarmMemoryLimit's policy relay, the
  _cf_recoveryAlarmCallbacks template hook, Scheduler.applyMemoryLimitPolicy,
  and
  setLifecycleAlarmMemoryLimitStrikes. AIChatAgent and Think flag their
  routed recovery fallback via chatRecoverySchedulePolicy and seal in-flight
  incidents from their own protected onAlarmMemoryLimit hooks; both now
  require agents >= 0.23.0 from the pending release batch (they consume its
  new agents/chat recovery exports and no longer implement the old
  template-method breaker hooks). Agent retains a
  sealed-only call to _cf_sealMemoryLimitedRecovery so already-published chat
  packages whose peer ranges accept agents 0.23 keep terminal notifications;
  that fallback carries no callback-name or queue policy.

@cloudflare/think@0.18.0

Minor Changes

• #2196 ec93caf Thanks @mattzcarey! - Replatform Think conversation storage onto agents/sessions and prompt context onto agents/context.

  Existing subclasses keep compiling and running. configureSession(session) still accepts the withContext() / withCachedPrompt() chain, this.session still carries addContext, getContextBlock, replaceContextBlock, refreshSystemPrompt, freezeSystemPrompt, tools(), and the rest, and appendMessage(message, parentId) / getHistory(leafId) still take their positional arguments. Those context methods are deprecated forwards to the new this.context; new code should declare blocks in configureContext() and read this.context directly. withCachedPrompt() is a no-op because the frozen prompt is always persisted now.

  What you may want to change

  • Declare prompt blocks with the new configureContext() hook instead of withContext(). Blocks from both are merged, configureContext() first.
  • Read context through this.context (a ContextBlocks from agents/context) instead of this.session.
  • Import Session from @cloudflare/think when you annotate a configureSession override. The class exported from agents/sessions is the raw storage handle and is not assignable to Think's.

  Behaviour changes on upgrade

  • Storage migrates on first wake and cannot be rolled back. Each Durable Object lifts its assistant_messages, assistant_compactions, and assistant_config rows into the cf_agents_session_* tables, verifies every row landed, and drops the old tables. An object that has woken on this version has an empty conversation if you roll back to the previous release; rolling forward again is safe. Deploy behind a canary if you need a rollback path.
  • hydrationByteBudget defaults to 32 MiB (was 24 MiB) and is now a hard ceiling that charges each row its full stored size, attachments included. There is no message-count floor, so an unusually large recent window can hydrate fewer than four messages. getHistory() still reads the full path.
  • Context blocks load during onStart, as before the replatform, so this.context.getBlock() answers as soon as the object has started.
  • session.search() still works. Its index is now built by the first search on an object rather than maintained on every append, so a Think that never searches stops paying a second billed row per message.
  • Think no longer reads Sessions tables with raw SQL. If you queried assistant_messages yourself, use this.session.history() or getHistory().

  Removed

  • sessionAttachments. There is nothing to configure about how Sessions stores a message: media leaves the row into a content-addressed attachment store and a message larger than one SQLite row is split across continuation rows, losslessly.
  • getRecentHistory(budget, minRecentMessages): the second argument is accepted and ignored.
  • compactAfter(threshold, { tokenCounter }): the counter option is accepted and ignored; the trigger reads the estimate Sessions stamps on each row.

• #2175 8ffb3ad Thanks @mattzcarey! - Lifecycle owns a durable job queue, driven as an alarm event loop.

  The thing in the queue is a job: a serialisable callback address — the
  owning capability plus a function name — with a due time and a payload.
  Capabilities and the host push jobs through the scoped jobs surface;
  Lifecycle drives due jobs in timestamp order when the alarm fires, owns
  dispatch retries and platform-failure deferral, arms a deadman pre-alarm
  before driving so an isolate death mid-drive still wakes the object, and
  derives the physical alarm purely from queue state (queue mutations re-arm
  automatically; an exclusive job suppresses ordinary candidates).

  class Cleanup extends LifecycleCapability {
    async scheduleSweep(time: number) {
      await this.lifecycle.jobs.push({ id: "sweep", fn: "sweep", time });
    }
    onJob({ job }: LifecycleJobContext) {
      // drive result: nothing = complete, { rescheduleAt } = suspend,
      // "yield" = leave due and wake again immediately
    }
  }

  The pull-based alarm-contribution model is removed: capability
  getNextAlarm()/onAlarm(), host getNextAlarm(),
  LifecycleServices.alarms (rearm/disabled), and AlarmContribution
  are gone. Host onAlarm() remains and runs once per alarm invocation
  after due jobs are driven. Terminal application failures reach the
  owner's onJobError(), whose drive result decides advancement.

  The alarm memory-limit circuit breaker (#1825) moves from Agent.alarm()
  into the Lifecycle event loop, targeting the exact executing job; Agent
  contributes domain policy through the new onAlarmMemoryLimit() host
  hook, and Scheduler's __DO_NOT_USE_WILL_BREAK__handleAlarmMemoryLimit
  escape hatch is gone. After recording a strike the breaker now finishes by
  resetting the isolate with ctx.abort(reason, { retryAlarm: false })
  (retry of the handled alarm suppressed; the backoff alarm owns the next
  wake), and Agent.destroy() uses the same no-retry abort so a completed
  teardown's alarm cannot be retried into a fresh constructor that recreates
  the deleted schema.

  Scheduler keeps its entire public API and loses its storage and due-row
  loop: a schedule is one job whose fn is the callback name, and interval
  schedules are single-flight jobs. Existing cf_agents_schedules rows are
  migrated into the cf_agents_jobs queue on startup and the legacy table
  is dropped. Agent's public scheduling and keepAlive() APIs are
  unchanged; its keep-alive, fiber-recovery/facet housekeeping, and
  deferred-destroy wakes are now host jobs, and Think's
  workflow-notification wake replaces the removed _getExtensionAlarm().

• #2196 ec93caf Thanks @mattzcarey! - Keep media eviction a context-window technique, separate from how Sessions stores a message.

  How Sessions lays a message out in rows is invisible and lossless: a message too large for one row is split across continuation rows and reassembled byte for byte. Media eviction is a decision about the model's context: once media has aged past mediaEviction.keepRecentMessages on the active path, Think removes it from the conversation so the model stops re-reading a large image every turn, and leaves [evicted image/png, 812004 bytes; preserved at /attachments/evicted/<messageId>-<n>.png] in its place. The raw bytes are written to the Workspace at that path with their real mime type, so the workspace read tool puts the actual image back in context when the agent deliberately reads it. The rewritten message no longer carries the payload, so the bytes live in exactly one place.

  mediaEviction: false now means the model keeps seeing aged media. It no longer changes where Sessions keeps the bytes.

  minPartBytes is Think's context threshold and is no longer passed to Sessions as a storage setting. The marker text and the /attachments/evicted/<id>-<n>.<ext> paths are unchanged, so old markers keep resolving.

  MediaEvictionConfig.externalizeToWorkspace is deprecated and ignored: evicted bytes are always preserved. Existing configurations keep compiling.

  WorkspaceLike.writeFileBytes is optional. Eviction and skills projection need it to write raw bytes; a custom workspace without it keeps working and those two features log once and stand down.

Patch Changes

• #2194 6da4c44 Thanks @mattzcarey! - Run root-agent chat recovery continuations as chained Tasks instead of schedule rows. Initial recovery attempts deduplicate by incident, delayed retries use durable Task sleeps, and platform failures replay through Task claims. AI Chat and Think share one reserved recovery definition and preserve their existing bounded callback handoff behavior: a failure before handoff stays with the current queue execution, while a detached post-handoff platform failure enqueues exactly one replacement.

  Tasks now propagate condemned-isolate failures out of journaled steps and apply alarm memory-limit backoff and sealing to the run whose wake struck — claim stripped and deadline pushed, so startup reconciliation cannot resurrect it and the reclaim still sees an interrupted attempt. Task wake jobs are pushed with a single dispatch attempt so a platform failure rejects the alarm instead of being retried into a silent reschedule of the still-claimed run. Lifecycle gains trackAlarmWork(): work a job hands off at a bounded return stays inside that alarm's memory-limit breaker domain after the alarm returns, so other jobs stay live while a memory reset from the handoff still records a strike — one strike per reset however many flows observe it — and strikes clear only once no handed-off work is outstanding and the last of it settled clean. retain: false now removes failed and cancelled runs as well as completed runs, releasing journals and idempotency keys after every terminal outcome. Routed dynamic agents temporarily retain the root-owned schedule transport until Tasks supports routed child wakes.

  AI Chat and Think require agents >=0.23.0, the pending release batch containing the shared recovery Task definition and internal enqueue support.

• #2173 71ce28a Thanks @mattzcarey! - Replatform chat's resumable streams onto the agents/streams capability.

  ResumableStream is now a thin adapter over Streams: chat's in-flight turn output lives in the shared durable chunk log (cf_agents_streams / cf_agents_stream_chunks), packed ~10 wire chunks per stored segment for write economy, with completion/error mapped onto stream settlement and retention keyed off the stream row's updated_at (sweeps no longer scan the chunk table). Existing cf_ai_chat_stream_* tables migrate wholesale — including an in-flight stream — on first construction after upgrade, then are dropped. AIChatAgent and Think expose the backing capability as readonly streams, so any streams.read() consumer on the same Durable Object can observe chat streams. The chat wire protocol, replay handshake, and recovery behavior are unchanged.

• #2190 58c586a Thanks @mattzcarey! - Make the alarm memory-limit circuit breaker (#1825) a self-contained
  Lifecycle concern instead of an Agent-mediated one.

  Recovery-loop membership is now a property of the job row
  (LifecycleJobPushOptions.recoveryLoop): flagged jobs are backed off by
  the breaker on a strike and purged when it seals at the strike budget,
  without disturbing unrelated rows — a recovery schedule can no longer
  silently escape the breaker. The public ScheduleOptions vocabulary is
  unchanged: schedules only shape future work, and chat recovery reaches the
  flag through internal scaffolding (RecoveryLoopScheduleOptions) retained
  only for legacy rows and routed dynamic agents. Root recovery moves to Tasks;
  the scaffolding can be deleted when Tasks supports routed child wakes.
  Capabilities can react to a strike through the new optional onMemoryLimit
  hook, hosts through onAlarmMemoryLimit, and the context identifies the job
  that was executing when one exists. The strike budget is real Lifecycle
  configuration (Lifecycle.install(host, { maxAlarmMemoryLimitStrikes }))
  rather than a composition-root side channel. Until Tasks supports routed
  child wakes, a sealed recovery schedule also forwards the seal to its owning
  dynamic agent so a chat child under a plain Agent root persists its exhausted
  incident and terminal notification.

  Removed accordingly: Agent.onAlarmMemoryLimit's policy relay, the
  _cf_recoveryAlarmCallbacks template hook, Scheduler.applyMemoryLimitPolicy,
  and
  setLifecycleAlarmMemoryLimitStrikes. AIChatAgent and Think flag their
  routed recovery fallback via chatRecoverySchedulePolicy and seal in-flight
  incidents from their own protected onAlarmMemoryLimit hooks; both now
  require agents >= 0.23.0 from the pending release batch (they consume its
  new agents/chat recovery exports and no longer implement the old
  template-method breaker hooks). Agent retains a
  sealed-only call to _cf_sealMemoryLimitedRecovery so already-published chat
  packages whose peer ranges accept agents 0.23 keep terminal notifications;
  that fallback carries no callback-name or queue policy.

@cloudflare/agent-think@0.0.8

Patch Changes

• Updated dependencies [71ce28a, ec93caf, ec93caf, 6da4c44, 71ce28a, 87bd594, b40bc5b, 8ffb3ad, 71ce28a, ec93caf, ec93caf, 99e5e2e, ec93caf, 58c586a, b12dc0b, 71ce28a]:
  • agents@0.23.0
  • @cloudflare/think@0.18.0
  • @cloudflare/ai-chat@0.12.0

[devin-ai-integration]

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