Sigil 0.6.0

February 22, 2026release

This release brings Sigil much closer to full R7RS compliance, adds a complete web development workflow with live browser reloading, and introduces three new packages: a PEG parsing library, an Org Mode parser, and an XMPP client. Developer tooling improves significantly with rich error diagnostics, an enhanced MCP server, and watch mode for incremental builds.

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R7RS Compliance

The biggest area of work in this release. Sigil now supports nearly all of R7RS Small:

Control flow: dynamic-wind, do syntax, guard prompt limit raised for deeper exception handling
Macros: let-syntax, letrec-syntax
Modules: include, include-ci, import set modifiers (only, except, prefix, rename)
I/O: Bytevector ports, read-bytevector!, char-ready?, u8-ready?
Output: write-shared with datum labels for circular structure printing
Feature detection: features, cond-expand, syntax-error
Libraries: (scheme time), (scheme process-context), (scheme repl) with interaction-environment
Literals: #u8(...) bytevector literal syntax in compiler and reader

Web Development

A full live-development workflow for web applications:

Live reloading: nREPL server with SSE-based browser reload — edit code, see changes instantly
Higher-level UI components: Expanded component library for sigil-web
API refinements: Improved ergonomics for routing, form handling, and GET requests
CSS generation: css-sel for compound selectors
MCP browser tools: 7 new tools for live browser control (morph, navigate, execute JS, reload CSS, error overlay)
Demo application: Vinyl Vault, a full CRUD demo showcasing the web stack

New Packages

Package	Description
`sigil-peg`	Parsing Expression Grammars with S-expression DSL, backtracking, and captures
`sigil-org`	Org Mode parser producing SXML (headlines, metadata, source blocks, tables, lists)
`sigil-xmpp`	XMPP client with STARTTLS, SASL (SCRAM-SHA-1/PLAIN), roster, presence, and MUC

Supporting packages: sigil-crypto gains HMAC-SHA1 and PBKDF2-SHA1, sigil-tls adds tls-upgrade for STARTTLS.

Developer Tooling

Rich error diagnostics: Structured error type hierarchy with Levenshtein-based "did you mean?" suggestions, source snippets with caret indicators in stack traces
MCP server: Package-provided tool discovery, multi-form eval, format auto-fix, runtime doc fallback for undocumented exports, nREPL describe and modules operations
Watch mode: sigil build --watch and sigil test --watch with --format json support
Value inspection: New (sigil inspect) module for structured introspection via nREPL and MCP
Project templates: sigil init gains web-app, api-service, and mcp-tool templates
Docstring collection: Variable definitions now collect docstrings; native docs propagate through re-exports

Performance

Dict lookup: FNV-1a hash cached on string keys, avoiding repeated computation

Library Improvements

sigil-markdown: Inline parser rewritten using PEG grammars (~120 fewer lines, same behavior)
sigil-json: Handle UTF-16 surrogate pairs in unicode escapes per RFC 8259
sigil-docs: Re-export descriptions resolved from source module entries

Bug Fixes

Fixed SIGIL_NATIVES_MAX limit (increased to 2048) for projects with many native bindings
Fixed --no-color flag in test runner
Fixed git-fetch to include tags when updating cached bare repos
Fixed binary-safe nREPL wire protocol and SIGPIPE handling
Fixed MCP format tool crash