update docs for compile chain

docs/spec/pipeline.md

@@ -69,6 +69,7 @@ Optimizes the Mcode IR through a series of independent passes. Operates per-func
 6. **Move elimination**: Removes self-moves (`move a, a`).
 7. **Unreachable elimination**: Nops dead code after `return` until the next label.
 8. **Dead jump elimination**: Removes jumps to the immediately following label.
+9. **Compile-time diagnostics** (optional): When `_warn` is set on the mcode input, emits errors for provably wrong operations (storing named property on array, invoking null, etc.) and warnings for suspicious patterns (named property access on array/text). The engine aborts compilation if any error-severity diagnostics are emitted.
 
 See [Streamline Optimizer](streamline.md) for detailed pass descriptions.
 
@@ -134,6 +135,7 @@ Seeds are used during cold start (empty cache) to compile the pipeline modules f
 | `mcode.ce --pretty` | Print raw Mcode IR before streamlining |
 | `streamline.ce --types` | Print streamlined IR with type annotations |
 | `streamline.ce --stats` | Print IR after streamlining with before/after stats |
+| `streamline.ce --diagnose` | Print compile-time diagnostics (type errors and warnings) |
 
 ## Test Files
 
@@ -146,3 +148,4 @@ Seeds are used during cold start (empty cache) to compile the pipeline modules f
 | `qbe_test.ce` | End-to-end QBE IL generation |
 | `test_intrinsics.cm` | Inlined intrinsic opcodes (is_array, length, push, etc.) |
 | `test_backward.cm` | Backward type propagation for parameters |
+| `tests/compile.cm` | Compile-time diagnostics (type errors and warnings) |

docs/spec/streamline.md

@@ -178,6 +178,36 @@ Removes `jump L` instructions where `L` is the immediately following label (skip
 
 **Nop prefix:** `_nop_dj_`
 
+### 9. diagnose_function (compile-time diagnostics)
+
+Optional pass that runs when `_warn` is set on the mcode input. Performs a forward type-tracking scan and emits diagnostics for provably wrong operations. Diagnostics are collected in `ir._diagnostics` as `{severity, file, line, col, message}` records.
+
+This pass does not modify instructions — it only emits diagnostics.
+
+**Errors** (compilation is aborted):
+
+| Pattern | Message |
+|---------|---------|
+| `store_field` on T_ARRAY | storing named property on array |
+| `store_index` on T_RECORD | storing numeric index on record |
+| `store_field` / `store_index` on T_TEXT | storing property/index on text |
+| `push` on T_TEXT / T_RECORD | push on text/record |
+| `invoke` on T_NULL / T_INT / T_FLOAT / T_NUM / T_TEXT / T_BOOL / T_ARRAY | invoking null/number/text/bool/array |
+| arity mismatch (module imports only) | function expects N arguments, got M |
+
+**Warnings** (compilation continues):
+
+| Pattern | Message |
+|---------|---------|
+| `load_field` on T_ARRAY | named property access on array |
+| `load_field` on T_TEXT | named property access on text |
+| `load_dynamic` with T_TEXT key on T_RECORD | text key on record |
+| `load_dynamic` with T_RECORD / T_ARRAY / T_BOOL / T_NULL key on T_RECORD | record/array/bool/null key on record |
+
+The engine (`internal/engine.cm`) prints all diagnostics and aborts compilation if any have severity `"error"`. Warnings are printed but do not block compilation.
+
+**Nop prefix:** none (diagnostics only, does not modify instructions)
+
 ## Pass Composition
 
 All passes run in sequence in `optimize_function`:
@@ -191,6 +221,7 @@ simplify_booleans
 eliminate_moves
 eliminate_unreachable
 eliminate_dead_jumps
+diagnose_function        → optional, when _warn is set
 ```
 
 Each pass is independent and can be commented out for testing or benchmarking.