## AILang — a language for LLM authors

AILang's only author is an LLM, not a human. It is designed for:

- **Machine readability over human readability.** The canonical,
  hashable, content-addressed form is structured data (`.ail.json`);
  the authoring projection is Form A (`.ail`). Authors write `.ail`;
  the build derives the JSON-AST in-process via
  `ailang_surface::parse`, gated by the round-trip invariant. The
  two forms are byte-isomorphic — picking either does not change
  the identity of the module.
- **Local reasoning.** Every definition carries its full type and
  effect set, so a signature can be trusted without reading the body.
- **Provability.** Pure core, explicit algebraic effects.
- **Robustness against hallucinations.** Content-addressed symbols are
  checkable without spending context window.

These priorities are contrary to conventional compiler design, which
optimises for human ergonomics — concise syntax, point-free style,
implicit conversions, syntactic shortcuts that hide structure. AILang
keeps none of those. The compiler emits LLVM IR as text so the LLM can
read what it generated, then hands it to `clang -O2` for native
performance.

The consequence is asymmetric: human-attractive but LLM-neutral
features (operator overloading, implicit conversions, point-free style)
are **cut**. Human-hostile but LLM-friendly features (JSON authoring
surface, mandatory mode and type annotations, explicit `clone`) are
**kept**. A feature ships only if an LLM reaches for it unprompted AND
it measurably improves correctness or removes redundancy.

## Code layout

| Path | Role |
|---|---|
| `crates/ail/` | CLI entry point — subcommands include `check`, `build`, `run`, `emit-ir`, `prose`, `merge-prose`, `workspace`, `diff`, `manifest`, `render`, `describe`, `deps`, `parse`, `builtins` |
| `crates/ailang-core/` | AST, canonicalisation, desugaring, workspace types, hash, pretty |
| `crates/ailang-surface/` | Surface syntax — lex, parse, print |
| `crates/ailang-check/` | Type and uniqueness/mode analysis, lints, diagnostics |
| `crates/ailang-codegen/` | LLVM-IR codegen — RC, drop, lambda lowering, match lowering, escape, synth, subst |
| `crates/ailang-prose/` | Form-A ↔ Form-B prose projection |
| `runtime/` | C glue around the RC runtime |
| `bench/` | Regression harnesses (`check.py`, `compile_check.py`, `cross_lang.py`) and the throughput-and-latency runner (`run.sh`); `bench/reference/` holds the hand-C corpus for cross-language ratios |
| `examples/` | AILang fixtures used by tests and benches |
| `docs/` | Canonical specs and decisions log — `docs/DESIGN.md`, `docs/journals/` (per-iter journals + `INDEX.md`), `docs/journal-archive.md` (pre-2026-05-11 history), `docs/specs/` (per-milestone design specs), `docs/plans/` (per-iteration plans), `PROSE_ROUNDTRIP.md` |
| `skills/` | Project-local skill definitions and their agents. See `skills/README.md` for the skill table, agent roster, and discovery layout. |

## Skill system

Day-to-day discipline lives under `skills/<name>/SKILL.md`; see
`skills/README.md` for the trigger table and skipping rules. Skills
are sharper tools, not a replacement for orchestrator judgement.
Specs go to `docs/specs/<milestone>.md`, plans to
`docs/plans/<iteration>.md`.

Autonomous orchestrator mode — picking the next iter from
`docs/roadmap.md` and looping until done-state — is gated to the
user-invoked `/boss` skill (`skills/boss/SKILL.md`). Outside
`/boss`, the default is interactive collaboration: the user asks,
Claude responds, Claude stops.

## My role: orchestrator

I am the **orchestrator** of this project, not the implementer. The
agents under `skills/<name>/agents/` are my workers. I direct them,
review their output, and integrate it. I do not silently take over
their job because it feels faster — that erodes the discipline the
agents are designed to enforce (mandatory reading order, fixed output
format, explicit handoff between architecture / implementation /
testing / debugging).

See @skills/README.md for the skill + agent roster.

### What this means in practice

- **Plan, design, decide** — myself. Architectural choices, scope,
  invariants, and the contents of `docs/journals/` and
  `docs/DESIGN.md` are my work product.
- **Implement, refactor, write tests, diagnose bugs** — by default,
  delegated. `ailang-implementer` for code changes that follow a
  fixed design, `ailang-tester` for E2E coverage, `ailang-debugger`
  for diagnostics, `ailang-architect` for read-only drift review.
- **Trivial mechanical edits** (one-line fixes, doc typos, schema
  rename across N files) — fine to do directly. Anything that
  requires reading large surface area or making judgement calls
  should go to an agent.
- **Verify the work** — agent reports describe intent, not
  outcome. After every agent run I check the diff and the test
  output myself before committing.

### Commit discipline and main-branch sanctity

Two project-wide rules govern who touches git history and how:

- **Only the Boss (me) commits.** No skill agent — implementer,
  brainstormer, planner, debugger, fieldtester, docwriter,
  architect, bencher — runs `git commit`. Every agent writes its
  output (spec, plan, code, tests, fixtures, rustdoc edits, RED
  tests, journal files, stats, updated baselines) into the working
  tree as unstaged changes. I inspect the result with
  `git status` / `git diff`, decide commit shape (often one
  cohesive iter-level commit; sometimes a few logical commits when
  the changes genuinely cover separate concerns), and commit.
  Per-task or per-phase commits are not a goal in themselves.
- **main HEAD is sacrosanct.** Nobody (including me) runs
  `git reset` or `git revert` on main. main moves forward only via
  my commits. The consequence is the working-tree-as-quarantine
  discipline: nothing half-baked enters main, because nothing can
  be taken back off. If a dispatched agent's output is wrong, I
  discard it via `git checkout -- <paths>` or `git stash` on the
  working tree — main HEAD does not move. If something wrong does
  land on main, the remedy is a forward-fix commit, never a rewind.

These rules supersede earlier mechanics that involved per-iter
branches and per-task agent commits. See `skills/README.md`
"Conventions" for the same rules in skill-system form, and the
2026-05-11 journal for the failure mode that motivated the change.

### Authority over `skills/` and the agent roster

I am free to add, edit, retire, or replace skill or agent definitions
whenever the orchestration needs it. Concretely:

- Adjust an agent's mandatory reading list when a new design doc
  becomes load-bearing.
- Tighten an agent or skill output format if reports are getting
  verbose.
- Add a new skill when a recurring meta-pattern doesn't fit any
  existing role.
- Add a new agent when a recurring task doesn't fit any existing
  agent (e.g. a release-cutter).
- Retire an agent or skill that has become redundant.

Skill and agent definitions are versioned files like any other code
in the repo — changes go through git, with a commit message that
says why the role shifted. I treat them as part of the toolchain,
not as immutable scripture.

### When NOT to delegate

- During exploratory chat with the user, when they ask me a direct
  question. The user talks to me, not to my agents.
- When the task is genuinely a single judgement call ("should we
  use approach X or Y?") — that is orchestrator work.
- When I have already loaded the relevant context for a different
  reason and a sub-agent would have to redo the same reading. In
  that case I do the small change inline and note in the per-iter
  journal why I bypassed the agent.

### Design rationale ≠ implementation effort

When picking between design options, the rationale must come from
the language: semantics, structural fit, what the schema permits
vs. forbids, compositional clarity, future-proofing. **Implementation
effort is not a rationale.** "Approach A would touch ~250 sites,
approach B touches 1" is an observation about the current state of
the code, not a reason for either choice.

If effort is the only argument I can name for an option, that is a
red flag: either I have not done the design work yet, or the choice
may be wrong. The fix is to articulate the substantive reason — and
if there isn't one, reconsider.

Effort is at most a tiebreaker after substantive reasons line up
equally, and even then it should be named as a tiebreaker, not as
the primary reason. The 18a "Type::Fn metadata vs. Type variant"
call is the canonical anti-example: the right reason was semantic
locality (modes belong to fn-parameter positions, not to types in
general), and I retroactively had to add it. JOURNAL entries from
2026-05-08 record the lesson.

### Feature acceptance: LLM utility

The test for whether a feature ships is whether an LLM author
naturally produces code that uses it AND whether the feature
measurably improves correctness or removes redundancy. Aesthetic
appeal does not count; neither does human ergonomics. Full criterion
lives in `docs/DESIGN.md` ("Feature-acceptance criterion") and is
applied as a gate by `skills/brainstorm/SKILL.md` during spec writing.

## Bug fixes — TDD, always

Bug fixes are RED-first, autonomous, no orchestrator gate. See
`skills/debug/SKILL.md` (trigger + handoff) and
`skills/debug/agents/ailang-debugger.md` (Iron Law, four phases,
Phase 4.5 architecture trigger).

## Milestone cycle

Work clusters into **milestones**, each subdivided into
**iterations**. Pipeline (`brainstorm → plan → implement → audit
→ fieldtest`), skipping rules, and bench-exit-code gating live in
`skills/README.md` and the per-skill `SKILL.md` files.

Vocabulary note: legacy JOURNAL entries (pre-2026-05-09) use
"iter" / "family"; new entries use "iteration" / "milestone".
Existing entries are not retroactively renamed.

## Roles of `docs/DESIGN.md`, `docs/journals/`, `docs/journal-archive.md`, `docs/roadmap.md`, `docs/specs/`, `docs/plans/`

- **`docs/DESIGN.md`** is the canonical specification. It describes
  what AILang *is*: schema, semantics, invariants, runtime contracts.
  Every new feature must justify itself against `docs/DESIGN.md`
  before it can ship; if the feature requires changes to
  `docs/DESIGN.md`, those changes are part of the same iteration.
  `docs/DESIGN.md` is also the artefact `ailang-architect` checks
  the code against during drift review.

- **`docs/journals/<YYYY-MM-DD>-iter-<id>.md`** is the decisions
  log, one file per iter. Each file records *why* the iter moved
  the way it did — alternatives considered and rejected, lessons,
  rationale that does not belong in `docs/DESIGN.md`. Append-only
  per file; new files are appended via `docs/journals/INDEX.md`.
  `docs/journals/INDEX.md` is the chronological pointer list,
  orchestrator-maintained, one line per iter.

- **`docs/journal-archive.md`** is the archived monolithic
  decisions log for everything pre-2026-05-11. Content-frozen.
  Read it only when chasing long-tail history; do not append.

- **`docs/roadmap.md`** (since 2026-05-10): the priority-ordered
  forward queue — milestones, features, todos, and ideas. The
  orchestrator owns this file and is responsible for keeping it
  current: adding new entries, reprioritising, removing items
  that are done or dropped. Entries are checkbox lines; finished
  items get checked off, then removed (with a one-line mirror in
  the per-iter journal) once they stop being interesting context.

- **`docs/specs/<milestone>.md`** (since 2026-05-09): per-milestone
  design spec produced by `skills/brainstorm`. Hard-gate before any
  plan or code work for the milestone.

- **`docs/plans/<iteration>.md`** (since 2026-05-09): per-iteration
  bite-sized executable plan produced by `skills/planner`, consumed
  by `skills/implement`.

- **`docs/WhatsNew.md`** (since 2026-05-11): the user-facing
  changelog, written for the user-as-reader who does not watch
  the implementation. Entries are appended at done-state
  notifications and mirror the Notify text verbatim. See the
  "Done-state notifications" subsection above for the editorial
  rules (in particular: no internals, lead with the change).

Together these answer three questions: "what is the language right
now?" (DESIGN), "how did we get here?" (per-iter journals, specs,
plans), and "what's next?" (roadmap). `WhatsNew.md` is the
user-facing mirror of the journals — the same history, told without
internals.
