AHP Swift Package v0.4.0

[0.4.0] — 2026-06-19

Implements AHP 0.4.0.

Added

• MessageOrigin struct and MessageKind enum now type Message.origin
  (previously an untyped AnyCodable); MessageKind covers user, agent,
  tool, and systemNotification, adding faithful agent- and tool-initiated
  origins.
• ConfigPropertySchema.additionalProperties — optional field describing the
  schema for object-typed config properties beyond those in properties.
• ChangesetContentChangedAction for full-replacement changeset file
  snapshots with optional operations and error details.
• ChangesetOperationStatus.disabled — new case for changeset operations
  that are currently unavailable and cannot be invoked.
• ChangesetOperation.group — optional identifier for grouping related
  changeset operations together in the UI.
• _meta (meta) field on the per-turn chat actions (chat/turnStarted,
  chat/delta, chat/responsePart, chat/reasoning, chat/usage,
  chat/turnComplete, chat/turnCancelled, chat/error) — optional
  provider-specific metadata so hosts can carry portable per-event context,
  such as attributing an event to a specific agent (e.g. a sub-agent acting
  within the turn).

Changed

• ToolResultSubagentContent.resource is now specified as the spawned worker
  chat URI (ahp-chat:/<cid>), not a session URI — a tool-spawned
  sub-agent is a chat. Its doc now describes the correspondence with the worker
  chat's ChatOrigin.tool record (matching toolCallId), which remains the
  canonical representation of the spawn relationship.
• BREAKING: SessionStatus is now an OptionSet with a UInt32 rawValue
  (was Int), an unsigned 32-bit bitset that preserves combined and unknown
  forward-compat bits. Combine flags with set-union (∪ / union) and test
  membership with contains(_:).
• BREAKING: ChangesetOperationTarget's range target now carries a nested
  TextRange ({start: {line, character}, end: {line, character}}) instead of
  a flat {start, end} integer pair.

Added

• SnapshotState.resourceWatch case and matching
  MultiHostStateMirror.resourceWatches slot, so applySnapshot(host:snapshot:)
  can seed an ahp-resource-watch: channel's descriptor (root URI, recursive
  flag, optional includes/excludes) alongside the existing root / session /
  terminal / changeset / annotations slots. reset(host:) / reset() clear
  the new slot.

Fixed

• AnyCodable.encode no longer corrupts NSNumber-backed Int/Double values to Bool/Int. NSNumber is now special-cased before the generic Swift type arms, using CFBooleanGetTypeID() to distinguish boolean from numeric NSNumber instances.
• AnyCodable.encode(to:) now preserves unsigned integers above Int64.max (encoding NSNumber values whose objCType is unsigned via uint64Value instead of the signed int64Value fallback), and the AnyCodable.swift template in scripts/generate-swift.ts reproduces the full encode/equality logic so regenerating the scaffold no longer reintroduces the bug.
• MultiHostClient/host runtime now advertises the generated SUPPORTED_PROTOCOL_VERSIONS on initialize instead of a stale hard-coded "0.2.0".
• Session reducers now apply _meta (meta) updates from every
  tool-call-scoped action, not only session/toolCallStart.

Added

• annotationsReducer implemented; annotations conformance fixtures (210–219) now pass.

• AnnotationsUpdatedAction (annotations/updated) — partially updates an
  existing annotation's turnId / resource / range / resolved without
  resending its entries. Handled by the annotations reducer (no-op on unknown
  id).

• ahp-chat: channel for per-chat conversation state; SessionState.chats[] catalog; SessionState.defaultChat? input-routing hint; ChatOrigin provenance union; createChat / disposeChat commands.

• SessionChatAddedAction, SessionChatRemovedAction, and SessionChatUpdatedAction handling for incremental chat catalog updates.

• ChatSummary.workingDirectory — optional per-chat working directory. Falls back to the session's workingDirectory when absent.

• SessionDefaultChatChangedAction (session/defaultChatChanged) — updates SessionState.defaultChat to steer new input to the designated chat; absent value clears the hint.

• ErrorInfo.meta: [String: AnyCodable]? — optional provider-specific metadata bag on error payloads (serialized as _meta), mirroring the existing meta field on UsageInfo and other protocol types. Clients MAY inspect well-known keys here for richer, localised error UI.

• RootState now exposes an optional _meta property bag (meta: [String: AnyCodable]?) for implementation-defined agent-host metadata, such as a
  well-known hostBuild key carrying the host's build version/commit/date.

• changesetReducer and resourceWatchReducer — the two state reducers
  that were missing from the Swift client are now implemented, mirroring the
  canonical TypeScript reducers (and the Kotlin/.NET clients). changesetReducer
  folds changeset/* actions into ChangesetState; resourceWatchReducer
  treats resourceWatch/changed as a documented event pass-through. The
  fixture-driven reducer test no longer silently skips the terminal, changeset,
  and resourceWatch fixture families — they now decode and assert, with the
  remaining gaps (unknown-discriminant response part; the not-yet-implemented
  annotations channel) pinned by an explicit drift tripwire.

Changed

• ChatState is now flat — the previous embedded summary has been replaced with inlined resource / title / status / activity / modifiedAt / model / agent / origin / workingDirectory properties. ChatSummary remains as the standalone catalog entry on SessionState.chats.
• ChatSummary.modifiedAt and ChatState.modifiedAt are now ISO 8601 String values instead of Int64/UInt64 milliseconds.

Added

• ChatSummary.interactivity / ChatState.interactivity ("full" | "read-only" | "hidden") indicating how the user can interact with a chat. Absent defaults to "full".

Removed

• SessionChatsChangedAction (replaced by the three discrete chat-catalog actions above).

Fixed

• Encode-fidelity: an unknown StateAction variant no longer re-encodes to
  {} (dropping its type discriminant and extra fields); the raw payload is
  preserved on decode and re-emitted verbatim.
• Forward-compatibility: unknown discriminants on wire-decoded discriminated
  unions (ResponsePart, ToolCallState, TerminalClaim,
  TerminalContentPart, Customization, and other evolvable unions) now decode
  to a raw passthrough and re-encode verbatim instead of throwing
  DecodingError, so a snapshot carrying an unknown variant still decodes and
  subsequent actions fold correctly.
• ChangesetOperationResourceTarget / …RangeTarget now encode their kind
  discriminant (previously a computed property excluded from CodingKeys, so it
  was dropped on encode).