# Session handoff — 2026-10-03 (two-phase frontend, slices 1–5)

State: branch **`ast-stage-c`** (off `1c93f19`, not merged to `master`).
Suite **178/178**; self-hosting fixpoint **OK** (**3,021,285 bytes**).
Working tree clean except the user's `compiler/toto.mod`.

Plan of record: `docs/plan-two-phase.md`.  Start: §4 slice 3
(statements) or §4 slice 4 (declarations).

## What landed (all inert — emitted `.ssa` unchanged, fixpoint byte-identical)

| Tag | Docs | What |
| --- | --- | --- |
| `v3-ast-slice1` | `summary_two-phase-slice1.md` | `AST` linked into the build; `twoPhase` flag; `AST.Init` per unit |
| `v3-ast-slice2` | `summary_two-phase-slice2.md` | expression spine + literals + parens + unary minus (`astCur`, per-invocation `astIsLit`) |
| `v3-ast-slice3` | `summary_two-phase-slice3.md` | `Design`: identifiers, `[i]`, `.f`, `^`, qualified names |
| `v3-ast-slice4` | `summary_two-phase-slice4.md` | calls/`NkCall` with actuals, `NOT`, builtins as named `NkCall`s |
| `v3-ast-slice5` | `summary_two-phase-slice5.md` | statements: `NkBlock`, assign, `IF`/`WHILE`/`REPEAT`/`LOOP`/`EXIT`/`FOR`/`RETURN`/`HALT`, calls |
| `v3-ast-slice6` | `summary_two-phase-slice6.md` | declarations: `NkDeclSeq`, `NkConstDecl`, `NkTypeDecl`, `NkVarDecl`, `NkProcDecl` (types by `ty` index) |
| `v3-ast-slice7` | `summary_two-phase-slice7.md` | unit root `NkUnit(name, decls, body)`; builtin statements `INCL`/`INC`/`NEW`/… as `NkCall`s |
| `v3-ast-slice8` | `summary_two-phase-slice8.md` | `CASE`/`WITH` statements (incremental nodes, no local arrays) |

The AST is **built alongside** the existing lowering; nothing consumes it
yet.  Each slice was gated by `build.sh` + `run_tests.sh` + `fixpoint.sh`,
and the tree shape was checked with a **temporary `AST.Dump`** in the root
production (removed before each commit).

## Not converted yet (still `NoNode`)

- Statements: (all core statements done; `CASE`/`WITH` as of slice 8).
- Expressions: brace/set literals, `ResultComp` call suffixes.
- Declarations: imports, `CLASS`, nested modules in the unit AST.
- **`Lower` + `.ssa` byte-compare** (the point where the old emit path
  gets deleted) — not started.

## Known bug found this session

**Local arrays in a `PROCEDURE` are miscompiled** (module-level arrays
are fine).  Repro + detail: `docs/wip/local-array-bug.mod`; observed 1,
want 60.  Pre-existing, unrelated to the refactor, but it bit the
self-hosted fixpoint when `IfStat` used a local `ARRAY`.  Worth a
dedicated fix (same family as the Stage-A array-of-record stride bug).

## Design notes for the next slice

- Expression result slot: module-level `astCur`, saved into locals by the
  combination productions; `Fact` uses a per-invocation `astIsLit`
  (nested facts cannot corrupt an outer one).
- Statement result slot: module-level `astStmt`; `StatSeq` folds into
  `NkBlock`; calls use the `AstCallNode` helper over `astArgs`/`astNArgs`.
- `AST` nodes: `NkDesignator(base, selectors…)`, `NkSelector(op)` with
  `SelField`/`SelIndex`/`SelDeref`, `NkCall(callee, actuals…)`, plus the
  kinds/ops in `compiler/src/AST.def` (`OpNot` was added).
- **Do not use local arrays** in grammar actions until the bug above is
  fixed; use scalars or module-level scratch.

## Resume / verify

```sh
cd ~/Projets/Projets-Modula2/MyWork/m2compiler-V3
git checkout ast-stage-c
cd compiler && ./build.sh && ./run_tests.sh   # 178/178
cd .. && ./bootstrap/fixpoint.sh              # FIXPOINT OK
```