Roadmap

Cairn ships monthly minor releases under date-based versioning YYYY.M[.PATCH]. Each month delivers what is ready; nothing is held back for an arbitrary “1.0”. Six named milestones cross-cut the monthly schedule so contributors and consumers can plan against something more durable than a calendar tick.

Schedule is a plan, not a promise. The compiler is implemented in the open and slips happen. The CHANGELOG is the source of truth for what actually shipped.

Release cadence

• Monthly minor (YYYY.M.0) on the first of the month. The release PR is opened by a cron job and merged after human review.
• Patches (YYYY.M.N, N ≥ 1) are cut on demand from main whenever a relevant commit lands. Typical triggers: registry/constraint pack updates, regressions, and security fixes. No upper bound on patches per month.
• Channel: there is only one — stable. Cairn does not run a separate nightly or beta train. Behaviour that is not yet stable is gated by compatibility tier, not by release channel.
• Backports: none. The latest release is the supported release. Older YYYY.M.* lines do not receive further patches.

Milestones

Each milestone is a “the project can credibly do X” gate, hit when the corresponding month ships. Naming the gates separately from version numbers gives the roadmap a stable vocabulary even when the monthly schedule shifts.

Milestone	Lands by	The thing it earns
M1 — source parses	2026.7.0	cairn parse produces an AST for every example in examples/
M2 — minimal build	2026.10.0	cairn compile writes a Java .nbt for a single-room structure with floor and walls, plus a lockfile
M3 — examples work	2027.1.0	cottage, themed-tower, village all round-trip through cairn compile --edition java and load in Minecraft
M4 — Java/Bedrock parity	2027.2.0	Same DSL source emits valid output for both editions; parity table populated; per-edition theme fallbacks work
M5 — developer experience	2027.3.0	cairn-lang-lsp provides diagnostics and completion in at least one editor (VS Code)
M6 — redstone simulates	2027.5.0	Logical redstone synthesis, place-and-route, and tick simulator land together; redstone-door example verifies

Monthly scope

The month → release contents table below is the working plan. It is denser than the milestone table because monthly minors can ship without crossing a milestone gate.

Release	Scope added
2026.7.0	cairn-lang-core lexer/parser, cairn parse subcommand (AST display only). Release automation goes live.
2026.8.0	Intent IR; syntactic validation; cairn check.
2026.9.0	Semantic layer; materials and themes basics; cairn info reports the three version axes.
2026.10.0	Block-array pivot; Java backend (walls and floors only); lockfile (build.cairn.lock).
2026.11.0	cottage.crn compiles end-to-end for --edition java.
2026.12.0	Registry pack ingest; fail-loud errors with nearest-valid suggestions.
2027.1.0	All examples/ work on Java. M3.
2027.2.0	Bedrock backend with parity table and per-edition theme fallbacks. M4.
2027.3.0	cairn-lang-lsp minimal (diagnostics + completion); VS Code extension. M5.
2027.4.0	Redstone logical layer; combinational synthesis and place-and-route.
2027.5.0	Redstone tick simulator; sequential macros; redstone-door verifies. M6.
2027.6.0	cairn-lang-wasm + browser playground (live compile in the docs site).

Beyond 2027.6.0 the schedule is intentionally not drawn. Once M6 lands the spec-driven part of the project is largely complete and the roadmap will be redrawn around real usage feedback.

How the schedule is enforced

The release strategy itself is automated:

1. Monthly minor PR is opened by a GitHub Actions cron at 17:04 UTC on the first of each month (deliberately offset from the hour boundary, where GHA crons are most likely to be delayed or skipped).
2. Version is computed from existing tags: no vYYYY.M.* tag yet → next is YYYY.M.0, otherwise the next in-month patch.
3. release-plz generates the version bump and changelog, applies the computed version via --version-overrides, and opens a PR.
4. Human review is mandatory for the monthly minor. Patches from main push events follow the same PR flow; merging triggers the publish pipeline.
5. Publish runs on the resulting v* tag: cross-compile binaries for Linux, macOS, and Windows on x86_64 and aarch64; sign with sigstore; attach to a GitHub Release; and cargo publish every workspace crate to crates.io.

Compatibility expectations across this schedule are defined separately by compatibility tier: .crn syntax and the lockfile evolve under Stable rules, the Rust API stays Internal (#[doc(hidden)]) until M3, and most other surfaces sit at Evolving for now.