Sigil (0.13.0)

Native sigil CLI

sigil build sigil-cli -c release produces a fully native binary. No extra flags required — the workspace release config declares backend: 'native. All shippable configs (release, prerelease, and every cross-compile target) now declare backend: 'native; the WASM target keeps the bytecode VM.

Linux x86_64 ships in two variants:

• sigil-linux-amd64 — dynamic glibc, cross-compiled via zig. The default download for normal distro users: smaller, faster startup, plays with system libc.
• sigil-linux-amd64-static — static musl. Self-contained bootstrap binary for unknown distros, containers, and downstream CI that needs "runs anywhere."

Showcase: Cinder Cantata

Cinder Cantata v0.2.0 — a music-reactive bullet-hell built on Sigil — ships alongside this release as a demonstration of the native backend's performance. The full game loop runs on the 0.13.0 runtime: native codegen for the per-frame hot path, goroutines for audio streaming, FFI for graphics/audio sokol bindings, and the motif audio composition engine driving enemy bullet patterns in lockstep with the soundtrack. Download a playable binary for Linux x86_64 from the release page.

Language Server (sigil lsp serve)

Sigil now ships a full LSP 3.17 implementation, invoked as sigil lsp serve. Editors and coding agents can wire it up over stdio for:

• Diagnostics — reader errors, compile errors, and lint warnings reported inline with source spans
• Hover — signature + full docstring for any binding at point, with fallback to the runtime spec when source isn't available
• Completion — context-aware completion items with proper filterText and textEdit for editors like eglot
• Go-to-definition — jumps to the exporting .sgl source line; descends into library re-exports
• Formatting — full-document and range formatting via (sigil format)
• Quick-fix code actions — suggest-import proposes imports for undefined bindings and remove-unused-import cleans up lint warnings; both offered on cursor position, not just on diagnostics
• Unused-import linter — detects unused imports with precise source spans, including inside re-exporting libraries

The server warms its docs index at initialized so first hover/completion is snappy. sigil lsp serve --log-file ... --log-level ... gives you traceable logs when debugging editor integrations.

Per-config backend: declarations

Build configs now declare their backend directly: (config name: 'release backend: 'native ...). Replaces the previous pattern where users had to use --backend native at build time. Each project's dev/release configs now declare their own backends (bytecode for fast iteration, native for shipping).

Per-package native compile pipeline

The native build pipeline was restructured to emit mod_*.c and compile to .o inside each package's build step instead of at the end in a silent 200K-line blob. Visible COMPILE mod_X.o per-package progress, parallelizable, better cache locality.

Cache correctness

Cache keys now include compiler identity + SGB version. Three caches (deps fetch, SGB auto-compile, runtime native) are keyed honestly against the exact compiler + runtime fingerprint they were produced with. Fresh checkouts and compiler rebuilds now produce consistent results instead of resurrecting phantom bytecode from a prior compiler version, eliminating a whole class of compiler errors.

Codegen optimizations (default-on)

• Escape analysis — closures whose captures don't escape the enclosing frame are now stack-allocated instead of heap-allocated. Includes a trampoline-frame fix for TAIL_CALL.proc.
• Cell elision v2 — post-conversion pass removes cells for variables that are read-only after definition. Register-allocator clobber bug that had blocked enabling cell elision by default (in 0.12.0) is fixed.

Both can be disabled via SIGIL_CPS_NO_CELL_ELISION=1 and similar env vars for the escape-analysis pass.

MCP server reliability

sigil-mcp (the Model Context Protocol server that lets Claude Code drive sigil) got a reliability pass:

• Subprocess isolation for the sigil/test tool (was inheriting sigil-mcp's environment)
• Per-server --log / --log-level flags for traceable multi-worker setups
• JSON-RPC id: null compliance for notification-shaped messages

Worker fleets running sigil-mcp across many concurrent Claude Code sessions are now stable.

Bug Fixes

• Self-rebuild trampoline crash — fixed a dangling inline_args pointer in the native-bridge trampoline. The pointer referenced a stack slot that had already been unwound by the time the trampoline bounced back through it. Harmless in short-running programs, fatal on the self-rebuild cycle where the compiler recursively compiles itself.
• Closure serialization across threads — cell elision could leave some captures as raw values while siblings remained upvalue cells. Value-level serialization now carries a per-capture is-cell flag, so deserialized closures rebuild with the exact capture shape the code expects. Fixes cross-thread closure passing under default codegen settings.
• Nested-guard codegen — exception-unwinding flag is now cleared after a tail handler fires, fixing a latent bug in deeply-nested guard forms.
• Compiler self-bootstrap — 0.12.0 compilers can now build 0.13.0 source without guarded-reference crashes (SIGIL_ABI_VERSION reference is #ifdef-gated).