plans: briefings for 5 language chisels + host/relations/artdag/dream

Language-chisel briefings (plans already existed): elixir, idris, linear, maude,
probabilistic. host-on-sx briefing (native server now, Dream framework layer next).
New subsystems relations-on-sx (cross-domain relationship graph on Datalog) and
artdag-on-sx (content-addressed dataflow DAG engine — art-dag's Analyze/Plan/Execute
on Datalog + persist + SX effects), each with plan + briefing. Un-parked
dream-on-sx: target user confirmed (rose-ash adopts Dream over Quart), gated only
on ocaml-on-sx Phases 1-5 + stdlib; added dream-loop briefing.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plans/agent-briefings/elixir-loop.md

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+# elixir-on-sx loop agent (single agent, queue-driven)
+
+Role: iterates `plans/elixir-on-sx.md` forever. **Elixir on the CEK/VM** — the
+companion to `lib/erlang/`. Most runtime semantics are Erlang's (BEAM); the
+chisel is the *Elixir-specific* surface: the macro system (`quote`/`unquote`),
+`|>`, `with`, `defmodule`/`def`/`defp`, protocol dispatch, structs. One feature
+per commit.
+
+```
+description: elixir-on-sx queue loop
+subagent_type: general-purpose
+run_in_background: true
+isolation: worktree
+```
+
+## Prerequisites — check before starting
+
+1. **lib-guest lex + pratt present** — Elixir's tokenizer/parser consume
+   `lib/guest/lex.sx` + `lib/guest/pratt.sx`.
+2. **`lib/erlang/` present** — Phase 2 reuses Erlang's pattern-match engine for
+   `=`, function heads, and `case`. Do not re-implement unification; import it.
+3. **ADT primitive (`define-type` + `match`)** in the SX core — needed for structs
+   (Phase 5). Track via `plans/sx-improvements.md`.
+
+**Pre-flight:**
+```
+ls /root/rose-ash/lib/guest/lex.sx /root/rose-ash/lib/guest/pratt.sx /root/rose-ash/lib/erlang/runtime.sx
+```
+If lib-guest or lib/erlang is missing, stop and record a Blockers entry. (The ADT
+primitive is only needed at Phase 5 — start earlier phases without it.)
+
+## Prompt
+
+You are the sole background agent working `/root/rose-ash/plans/elixir-on-sx.md`,
+in an isolated git worktree on branch `loops/elixir`, forever, one commit per
+feature. Push to `origin/loops/elixir` after every commit. Never touch `main` or
+`architecture`.
+
+## Restart baseline — check before iterating
+
+1. Read `plans/elixir-on-sx.md` — Roadmap + Progress log + Blockers tell you where
+   you are.
+2. Run the pre-flight. Record any missing prerequisite in Blockers.
+3. `ls lib/elixir/` — pick up from the most advanced file. No dir → Phase 1.
+4. If `lib/elixir/tests/*.sx` exist, run them via the epoch protocol against
+   `sx_server.exe` (`SX_SERVER=/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe`).
+   Green before new work.
+
+## The queue
+
+Phase order per `plans/elixir-on-sx.md`:
+
+- **Phase 1** — tokenizer + parser (`:atom`, charlists, `<>`, `|>`, `do/end`)
+- **Phase 2** — transpile basic Elixir (no macros/processes): arithmetic, pattern
+  match (reuse Erlang engine), `def`/`defp` clause dispatch, modules, `|>`, `with`,
+  `for`, `fn`/`&`, `cond`/`case`, interpolation, keyword lists/maps/tuples
+- **Phase 3** — **macro system** (`quote`/`unquote`/`unquote_splicing`, `defmacro`,
+  two-pass expand, `use`/`import`/`alias`) — the headline phase
+- **Phase 4** — protocols (`defprotocol`/`defimpl`, dispatch, `Enumerable` etc.)
+- **Phase 5** — structs + behaviours (`defstruct`, `%Mod{}`, `@behaviour`)
+
+Within a phase, pick the checkbox with the best tests-per-effort ratio.
+Every iteration: implement → test → commit → tick `[ ]` → Progress log → push → next.
+
+## Chisel discipline — the macro system
+
+Elixir earns its place by exercising **homoiconic macros on a non-Lisp surface
+syntax**. `quote do … end` must produce Elixir AST as SX list structure, and
+`defmacro` must run at expansion time receiving/returning that AST. The two-pass
+model (collect defs, then expand before transpile) is the crux — get it right in
+Phase 3. If macro hygiene exposes an SX gensym/quoting gap, that's a substrate
+note (Blockers), not an Elixir fix.
+
+## Ground rules (hard)
+
+- **Scope:** only `lib/elixir/**` and `plans/elixir-on-sx.md`. Do **not** edit
+  `spec/`, `hosts/`, `shared/`, `lib/guest/**` (read-only), `lib/erlang/**`
+  (read-only — import its pattern engine), or other `lib/<lang>/`.
+- **Reuse, don't re-implement.** Consume `lib/guest/` (lex, pratt) and `lib/erlang/`
+  (pattern matching) wherever they cover a need.
+- **Don't patch the substrate from this loop.** Failing core behavior → failing
+  test + Blockers entry + stop.
+- **NEVER call `sx_build`** (600s watchdog). Broken `sx_server.exe` → Blockers, stop.
+- **SX files:** `sx-tree` MCP tools ONLY; `sx_validate` after every edit. Never
+  `Edit`/`Read`/`Write` on `.sx`. They take `file:` not `path:`.
+- **Worktree:** commit, then push `origin/loops/elixir`. Never `main`/`architecture`.
+- **Commits:** one feature per commit. Short factual messages
+  (`elixir: |> pipe desugaring + 6 tests`).
+- **Plan file:** Progress log (newest first) + tick boxes every commit.
+- **Blocked 2 iterations on one issue → Blockers entry, move on.**
+
+## Elixir-specific gotchas
+
+- **Everything is an expression; blocks return their last value.** `do/end` is a
+  block, not a statement list — map to SX `(begin …)`.
+- **`|>` is transpile-time sugar:** `a |> f(b)` → `f(a, b)` (first-arg injection),
+  resolved before evaluation — not a runtime combinator.
+- **`with` short-circuits on the first `<-` mismatch to `else`** — desugar to nested
+  pattern-matched lets with an escape, not to `and`.
+- **Maps vs keyword lists:** `%{k: v}` → SX dict; `[k: v]` → SX list of `{:k v}`
+  (ordered, dup keys allowed). Don't conflate them.
+- **Atoms are not strings** — `:atom` is its own type; keep them distinct from
+  string values even though SX keywords collapse to strings.
+- **Macro args arrive as AST, not values** — `defmacro` receives quoted forms;
+  evaluate `unquote` islands only.
+
+## General gotchas (all loops)
+
+- SX `do` = R7RS iteration; use `begin` for multi-expr sequences.
+- `cond`/`when`/`let` clauses evaluate only the last expr — wrap multiples in `begin`.
+- `let` is parallel — nest `let`s when one binding references an earlier one.
+- `env-bind!` creates a binding; `env-set!` mutates an existing one.
+- Namespace-prefix guest helpers (`ex/…`) — short/host-colliding names get shadowed.
+- Shell heredoc `||` gets eaten — escape or use `case`.
+
+## Style
+
+- No comments in `.sx` unless non-obvious. No new planning docs — update the plan.
+- Short, factual commit messages. One feature per iteration. Commit. Log. Push. Next.
+
+Go. Run the pre-flight. If lib-guest or lib/erlang is missing, stop and report.
+Otherwise read the plan, find the first unchecked `[ ]`, implement it.