plans: briefings + roadmaps for lua, prolog, forth, erlang, haskell

Five new guest-language plans mirroring the js-on-sx / hs-loop pattern, each
with a phased roadmap (Progress log + Blockers), a self-contained agent
briefing for respawning a long-lived loop, and a shared restore-all.sh that
snapshots state across all seven language loops.

Briefings bake in the lessons from today's stall debugging: never call
sx_build (600s watchdog), only touch lib/<lang>/** + own plan file, commit
every feature, update Progress log on each commit, route shared-file
issues to Blockers rather than fixing them.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plans/lua-on-sx.md

@@ -0,0 +1,91 @@
+# Lua-on-SX: Lua 5.1 on the CEK/VM
+
+Compile Lua 5.1 AST to SX AST; the existing CEK evaluator runs it. Same architecture as `plans/js-on-sx.md` — reuse SX semantics wherever they fit, only shim the Lua-specific parts (tables/metatables, `nil`/`false`-only-falsy, multi-return, coroutines via `perform`/resume).
+
+End-state goal: **100% of PUC-Rio Lua 5.1.5 test suite.** Running as a long-lived background agent that drives the scoreboard up one failure-mode at a time, like `lib/js/`.
+
+## Ground rules
+
+- **Scope:** only touch `lib/lua/**` and `plans/lua-on-sx.md`. Do **not** edit `spec/`, `hosts/`, `shared/`, `lib/js/**`, `lib/hyperscript/**`, `lib/prolog/**`, `lib/stdlib.sx`, or anything in `lib/` root. Lua-specific primitives go in `lib/lua/runtime.sx`.
+- **Shared-file issues** go under "Blockers" below with a minimal repro; do not fix from this loop.
+- **SX files:** use `sx-tree` MCP tools only (never `Edit`/`Read`/`Write` on `.sx` files). `sx_write_file` for new files, path/pattern edits for changes.
+- **Architecture:** Lua source → Lua AST → SX AST → CEK. No standalone Lua evaluator.
+- **Commits:** one feature per commit. Keep `## Progress log` updated (dated entries, newest first) and tick boxes in the roadmap.
+
+## Architecture sketch
+
+```
+Lua source text
+    │
+    ▼
+lib/lua/tokenizer.sx     — numbers, strings (short + long [[…]]), idents, ops, comments
+    │
+    ▼
+lib/lua/parser.sx        — Lua AST as SX trees, e.g. (lua-for-num i a b c body)
+    │
+    ▼
+lib/lua/transpile.sx     — Lua AST → SX AST (entry: lua-eval-ast)
+    │
+    ▼
+existing CEK / VM
+```
+
+Runtime shims in `lib/lua/runtime.sx`: `lua-truthy?`, string coercion for `..`/arithmetic, table ops (array + hash part), metatable dispatch, `pcall`/`error` bridge, `string`/`math`/`table` libs.
+
+## Roadmap
+
+Each item: implement → tests → tick box → update progress log.
+
+### Phase 1 — tokenizer + parser
+- [ ] Tokenizer: numbers (int, float, hex), strings (short + long `[[…]]`), idents, keywords, operators, comments (`--`, `--[[…]]`)
+- [ ] Parser: blocks, `local`, `if/elseif/else/end`, `while`, numeric `for`, `function`, `return`, expressions, table constructors, indexing (`.`, `[]`), calls (`f(…)`, `f:m(…)`)
+- [ ] Skip for phase 1: generic `for … in …`, goto/labels, nested varargs `...`
+- [ ] Unit tests in `lib/lua/tests/parse.sx`: source → expected AST
+
+### Phase 2 — transpile: control flow + arithmetic
+- [ ] `lua-eval-ast` entry
+- [ ] Arithmetic (Lua 5.1 semantics — `/` is float)
+- [ ] Comparison + logical (short-circuit, Lua truthy)
+- [ ] `..` concat with string/number coercion
+- [ ] `if`, `while`, numeric `for`, `local`, assignment, blocks
+- [ ] 30+ eval tests in `lib/lua/tests/eval.sx`
+
+### Phase 3 — tables + functions + first PUC-Rio slice
+- [ ] `function` (anon, local, top-level), closures
+- [ ] Multi-return: return as list, unpack at call sites
+- [ ] Table constructors (array + hash + computed keys)
+- [ ] Raw table access `t.k` / `t[k]` (no metatables yet)
+- [ ] Vendor PUC-Rio 5.1.5 suite to `lib/lua/lua-tests/` (just `.lua` files)
+- [ ] `lib/lua/conformance.sh` + Python runner (model on `lib/js/test262-runner.py`)
+- [ ] `scoreboard.json` + `scoreboard.md` baseline
+
+### Phase 4 — metatables + error handling (next run)
+- [ ] Metatable dispatch: `__index`, `__newindex`, `__add`/`__sub`/…, `__eq`, `__lt`, `__call`, `__tostring`, `__len`
+- [ ] `pcall`/`xpcall`/`error` via handler-bind
+- [ ] Generic `for … in …`
+
+### Phase 5 — coroutines (the showcase)
+- [ ] `coroutine.create`/`.resume`/`.yield`/`.status`/`.wrap` via `perform`/`cek-resume`
+
+### Phase 6 — standard library
+- [ ] `string` — `format`, `sub`, `find`, `match`, `gmatch`, `gsub`, `len`, `rep`, `upper`, `lower`, `byte`, `char`
+- [ ] `math` — full surface
+- [ ] `table` — `insert`, `remove`, `concat`, `sort`, `unpack`
+- [ ] `io` — minimal stub (read/write to SX IO surface)
+- [ ] `os` — time/date subset
+
+### Phase 7 — modules + full conformance
+- [ ] `require` / `package` via SX `define-library`/`import`
+- [ ] Drive PUC-Rio scoreboard to 100%
+
+## Progress log
+
+_Newest first. Agent appends on every commit._
+
+- _(awaiting phase 1)_
+
+## Blockers
+
+_Shared-file issues that need someone else to fix. Minimal repro only._
+
+- _(none yet)_