[qoli]

Scope after review

Adds profile composition only: DynamicProfile, Profile, erasure, conditional builders, modifiers, and request-time resolution of those values. No profile session initializer, lifecycle execution, native projection, or provider Tool-loop changes.

Dependencies: #313 and upstream #352 (which replaced/closed #311). Shared compatibility runtime is separate in #315; provider integrations remain individual PRs.

API compatibility

• Composition follows the installed Foundation Models 27 SDK, including callback actor-context/isolation annotations.
• historyTransform accepts an ordinary escaping closure, not @sendable, matching Apple. A non-Sendable function/capture now compiles with both modules.
• Conditional branch storage/initialization remains internal.
• AnyLanguageModel-only includeSchemaInPrompt is Compatibility SPI.
• This PR does not decide the public session-construction contract; Add shared profile execution behind Compatibility SPI #315 currently retains its SPI initializer pending the outstanding construction decision.

Fresh validation (2026-10-21)

• Normal merge of updated Add session properties and Foundation Models 27 HistoryView compatibility #313 and upstream main 303f8a1; preserved the upstream Add Foundation Models 27 request options #352 options/defaults, Let callers set how many tool rounds a response takes #331 maximumToolRounds, Honour the tool execution delegate in SystemLanguageModel #297 native delegate, and Replay OpenAI tool calls as plain, stable JSON #325 JSON replay changes.
• CI=1 GIT_CONFIG_GLOBAL=/dev/null swift test: 848 tests in 89 suites passed.
• Regression first reproduced the non-Sendable-to-@sendable compile error. After the fix, equivalent ordinary function values compile against AnyLanguageModel and FoundationModels; a runtime test executes a transform capturing a non-Sendable reference.
• Strict Swift format lint on changed files and git diff --check passed.

The main-based diff includes unmerged #313; review the profile-specific files for this layer. Published history is preserved; no force-push or new checkout.

The updated #313 dependency preserves concrete Tool identity in public RequestContext and binds session properties only for execution. historyTransform remains an ordinary, non-@sendable closure; no construction API or provider runtime moved into this PR.

[Copilot]

🟡 Changes recommended

Request-scoped profile state can leak across overlapping requests, and history handling can violate its instruction-free contract.

5 open findings

• Bind callbacks to the producing request's canonical history · New
• Use request snapshot history for tool execution · New
• Serialize profile activation across awaited transitions · New
• Keep transcript policy request-scoped instead of session-global · New
• Filter instructions from durable HistoryView transcripts · New

What changed in this PR

Adds Foundation Models 27-compatible dynamic profiles, session properties, request options, and per-request lifecycle handling.

Changes:

• Adds dynamic profile composition, modifiers, callbacks, and request projections.
• Adds observable session properties and instruction-free history access.
• Adds Foundation Models 27 request-option bridging and compatibility tests.

File	Description
Sources/​AnyLanguageModel/​ContextOptions.swift	Defines request-context options.
Sources/​AnyLanguageModel/​DynamicInstructions.swift	Exposes instruction resolution internally.
Sources/​AnyLanguageModel/​DynamicProfile.swift	Implements profiles, modifiers, and lifecycle handling.
Sources/​AnyLanguageModel/​GenerationOptions.swift	Adds sampling aliases and tool-calling policy.
Sources/​AnyLanguageModel/​LanguageModelSession.swift	Integrates profile resolution and callbacks.
Sources/​AnyLanguageModel/​Models/​SystemLanguageModel.swift	Bridges tool-calling mode to Foundation Models.
Sources/​AnyLanguageModel/​SessionProperties.swift	Implements session-scoped property storage.
Sources/​AnyLanguageModelMacros/​Plugin.swift	Registers the session-property macro.
Sources/​AnyLanguageModelMacros/​SessionPropertyEntryMacro.swift	Generates session-property accessors and keys.
Tests/​AnyLanguageModelTests/​APICompatibilityAnyLanguageModelTests.swift	Checks AnyLanguageModel syntax compatibility.
Tests/​AnyLanguageModelTests/​APICompatibilityFoundationModelsTests.swift	Checks native Foundation Models compatibility.
Tests/​AnyLanguageModelTests/​DynamicProfileTests.swift	Exercises profiles and lifecycle behavior.
Tests/​AnyLanguageModelTests/​FoundationModelsGenerationOptionsTests.swift	Tests native option bridging.
Tests/​AnyLanguageModelTests/​RequestOptionsTests.swift	Tests new request-option values.
Tests/​AnyLanguageModelTests/​SessionPropertyTests.swift	Tests property storage and history behavior.
README.md	Documents Foundation Models 27 request options.

🧠 Review effort: Balanced

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[Copilot]

🟡 Changes recommended

Session history binding and callback concurrency currently permit cross-session state leakage and duplicate callback execution.

3 open findings

• Duplicate check and mark are not atomic · New
• Profile transform must be marked @​Sendable · New
• History lacks observation tracking and change notifications · New

5 resolved since last review

• Use request snapshot history for tool execution
• Bind callbacks to the producing request's canonical history
• Filter instructions from durable HistoryView transcripts
• Keep transcript policy request-scoped instead of session-global
• Serialize profile activation across awaited transitions

🧠 Review effort: Balanced

[Copilot]

🟡 Changes recommended

Unresolved history, session-isolation, callback-dispatch, and API compatibility issues affect correctness.

5 open findings

• Bind profile instruction history as read-only · New
• Add sampling-only GenerationOptions initializer · New
• Pass newly committed entries to completion callbacks · New
• Validate task-local history ownership before using it · New
• Use transcript mutation helper for completion and rollback · New

3 resolved since last review

• Duplicate check and mark are not atomic
• History lacks observation tracking and change notifications
• Profile transform must be marked @​Sendable

Previously missed (2)

In code that hasn't changed since last review

Preserve and deduplicate each request's prompt dispatch

Sources/​AnyLanguageModel/​DynamicProfile.swift:531

Two streams created back-to-back can append both prompts before their asynchronous profile resolutions run. Both snapshots then end with the second prompt, so this lookup dispatches onPrompt for that prompt and skips the first request's prompt. Pass the actual request prompt into lifecycle preparation instead of inferring it from shared history, and deduplicate prompt dispatch per request across continuations.

Build native history from the resolved transcript

Sources/​AnyLanguageModel/​LanguageModelSession.swift:121

Profile sessions now enter SystemLanguageModel's dynamic-instructions branch, but makeFoundationModelsSession builds its history from session.transcript (SystemLanguageModel.swift:404–412), not the resolved request projection. Thus a profile's historyTransform is ignored even on the initial system-model request, resending entries the transform removed. Build native history from the resolved RequestContext.transcript, filtering its instructions and duplicate current prompt without changing durable history.

🧠 Review effort: Balanced

[qoli]

The additional prompt-dispatch and native-history findings are also addressed in 9b76d74. Lifecycle preparation receives the actual request prompt and shares a per-request dispatch state across continuations, including concurrent streams. Native Foundation Models session construction now uses the resolved request projection. Regression coverage includes history mutation removing the current prompt, concurrent prompt callbacks, and native projected history without changing durable history. The 34 focused profile/property/options tests pass.

[Copilot]

🟡 Changes recommended

One or more issues must be addressed before approval.

5 open findings

• Type erasure loses the concrete profile's identity: resolution ultimately identifies a leaf by its… · New
• This creates another binding from the original history, discarding the binding updated during… · New
• Each entry starts a new history binding from the same snapshot. If onReasoning removes an earlier… · New
• The permanent session model is now this placeholder, but prewarm() and logFeedbackAttachment()… · New
• For sessions created with init(model:dynamicInstructions:), this now evaluates the instructions… · New

5 resolved since last review

• Validate task-local history ownership before using it
• Pass newly committed entries to completion callbacks
• Add sampling-only GenerationOptions initializer
• Bind profile instruction history as read-only
• Use transcript mutation helper for completion and rollback

🧠 Review effort: Balanced