Sailfin Enhancement Proposals

SFEP Purpose and Process

Sailfin Capsule & Model Management

Built-in Tooling

sfn check — Fast Analysis Without Codegen

Colon Type Annotations

Unified Build Architecture

sfn fmt — Canonical Formatter

Effect Validation as Build Gate

CLI Modularization

Tracks #351

Sailfin-Native Test Infrastructure

Tracks #965, #839, #842, #840

CI Test-Speed Plan

Tracks #1012, #843

Result<T, E> and the ? Operator

Tracks #321, #323

Host-Aware exe_path Intrinsic

Agent-Legible Build/Test Output

Toolchain Independence — Sailfin-Native Backend

Tracks #1640, #1641

The Capability-Sealed Runtime

Tracks #1639, #934, #1642, #1643

Hierarchical Sub-Effects as Subsumption

Tracks #1180, #1182

Borrow / Ownership Checking for the Native Runtime

Tracks #1207, #1209

sfn/http — Typed HTTP Surface

Tracks #1321

Compiler Decomposition

Tracks #345

Native Windows Self-Host (MSVC ABI)

Tracks #1485

Darwin (macOS arm64) Memory Governor

Capsule-Defined Decorators

Tracks #1557

Model Engines, Adapters, Tensors, Training

Native Runtime Architecture

Tracks #321, #322, #451, #822, #1089, #1118, #1181, #1203, #1209

Delivery Process — Drift-Tolerant Issues, Seed Discovery, Release Cadence

CLI Modularization — Per-Worker RSS Relief First, Then Migration

Tracks #1671

Typed / Generic-Element Array Higher-Order Functions (map / filter / reduce)

Tracks #1943, #1945

Lambda expression syntax for 1.0 — keep, reform, or defer

Tracks 690,1683

First-Class Function Values

Tracks #1609, #1610, #1172

Inline `export <declaration>` syntax

Tracks #1681, #1680

Infer untyped lambda parameter and return types from the expected call-site function type

Tracks 1683

Length-aware ({i8*, i64}) ABI for query-side string runtime helpers

Tracks 1704

Structured, Enforced `x is T` Type-Guard Operator

Tracks #1753

Deriving prelude-mirror registry signatures from the prelude (kill latent ABI drift)

Tracks #572, #1779, #1780

TLS termination + upstream TLS for the native runtime (OpenSSL)

Tracks #1540, #1820, #1821, #1822

Peer-Language Process Adoption — Merge Queue, ICE Discipline, Perf History, Corpus Runs, Reduction, Fuzzing

Tracks #1806, #1807, #1808, #1809 (Tier 1, §3.13)

Generic Type Parameter Constraints and Monomorphization

Tracks #1867, #1868, #1869, #1870, #1871, #1872

Nominal Object Model — Honest Rejection of TypeScript-Shaped Data Syntax

Tracks #1860, #1887, #1888, #1838, #1855, #1900, #1904, #1905

Global Artifact Cache Store and Garbage Collection

Tracks #1892, #1893

Unified expected-type + typing-environment context for the typecheck walk

Tracks #1900, #1904, #1905

Nested / Local Function Declarations (non-capturing static `fn` items)

Tracks #1609, #1922, #1935, #1940, #1950

Phase-scoped arena reclamation to reduce per-module peak RSS

Tracks #1989

Invocation-scoped runtime identity + in-process sha256 for the test runner

Tracks #1995, #1996, #1997, #1998, #1999, #2008, #2010

Shared-frontend test runner — parent compiles, children only execute

Tracks SFN-152, #2010, #1997

Native Toolchain Version Pinning + Dispatch

Tracks SFN-167, SFN-168, SFN-169, SFN-170, SFN-171, SFN-172

Compiler Bootstrap Manifest

Tracks SFN-197

Native crypto + TLS stack — removing the OpenSSL dependency

Effect-transparency for concurrency-primitive leaves (spawn / parallel / channel send·receive)

Tracks SFN-86, #1702

Streamed per-test results over a captured pipe (retiring the results.log/fail.bin side-channel)

Tracks SFN-393

Workspace Manifest — Multi-Capsule Policy and the Capability Envelope

Tracks SFN-413 (Phase 1 member declaration — multi-line arrays + glob, Done), SFN-412 (workspace.toml reflow after seed pin), SFN-414 (Phase 2 root [toolchain] default), SFN-415 (Phase 3 [workspace.package]/[workspace.dependencies] inheritance), SFN-416 (Phase 4a declared-surface capability audit), SFN-418 (Phase 4b inferred-surface audit), SFN-419 (Phase 4c sfn capabilities audit + enforce/warn gate), SFN-417 (Phase 5 default-members + exclude). Epic: Linear project 'Workspace Manifest & Multi-Capsule Policy'

Accelerated ML — Substrate Interop and Capability-Typed Accelerator Programming

Shape-Typed Tensor IR and Fusion

Tracks #2485, SFN-424, SFN-427, SFN-429

Low-Precision Numeric Substrate

Tracks #2484, SFN-423, SFN-426

Concurrency runtime maturity — cancel-on-fault and async I/O

Tracks #1540, #1963

Derivable Interface Implementations (@derive)

Compile-Time Match Exhaustiveness Checking

Generic Collections — Map, Set, and Tuple

Tracks #1941

Import-surface compaction across the phase rewind to cut emit peak RSS

Tracks SFN-382; supersedes SFN-94

Signature-Checked Interface Conformance

Nullable Access Operators (?. and ??)

Sized Integer Types and Overflow Semantics

String Interpolation with ${ } (migrating off {{ }})