feat(dbt+ai): build out cubedbt and cubeai packages (Package 4, PDF §549/§551)

cubedbt: DBT runtime that reads CZYX-stored translation rules and patches
them into a code cache to execute mimicked behavior. TranslationRule (CZYX
Variant record in c220 band) maps an op-class to a replacement bytecode
fragment; CodeCache patches an original CodeCell under eligible rules and
writes the result as a Variant (preserving behavior descriptors), and
DbRuntime.mimic() fetches -> patches -> runs in the real Vm, proving
're-run or modify behavior without the original binary'.

cubeai: models over cube-stored traces/graphs to classify blocks
(Computation/Branch/CallTrampoline/IoSection/Sequence from the op-class
histogram + behavior descriptors) and suggest new code sequences as
cubedbt TranslationRules (persisted into the c220 rule band, discoverable
by DbRuntime). End-to-end: trace -> classify -> suggest -> mimic.

Both crates are dependency-free and operate on the real CubeStore/CodeCell/
Vm/Behavior types, so they are exercisable today on HashBackend and slot
into ConcurrentStore later without an API change. ./check quick green:
cubedbt 4 tests, cubeai 5 tests, full workspace green.

cubeai/src/lib.rs

@@ -0,0 +1,327 @@
+//! CUBELinux-2 AI layer.
+//!
+//! Per the PDF (Package 4, §551): *"cubeai: models that operate on
+//! cube‑stored traces/graphs to classify blocks, infer higher‑level
+//! operations, and suggest new code sequences or orchestrations."*
+//!
+//! This crate is the *structured decision* layer sitting on top of the
+//! substrate (and on [`cubedbt`]). It is deterministic and dependency-free
+//! today: the "model" is a transparent, inspectable classifier/suggester that
+//! operates on the same [`CubeStore`] / [`CodeCell`] / [`Behavior`] types the
+//! rest of the workspace uses. A learned model can later implement the same
+//! traits without changing callers.
+//!
+//! Pipeline (the end-to-end story from §549–§551 + §554):
+//!   trace (cube) → classify blocks → infer higher-level op →
+//!   suggest `TranslationRule`s → hand to `cubedbt` to patch + run (mimic).
+
+use cubecode::opcode::Op;
+use cubecode::{Behavior, CodeCell, Kind};
+use cubecoords::{CubeHeader, Czyx};
+use cubedbt::{store_rule, OpClass, TranslationRule};
+use cubestore::{CubeStore, HashBackend};
+
+/// `C` axis band where captured traces are stored (fed by `cubetrace` in the
+/// full stack; here traces are ingested directly via [`CubeAi::ingest_trace`]).
+pub const C_TRACE: u8 = 230;
+
+/// A captured basic block: its coordinate, the op-class histogram observed
+/// during tracing, and the behavior descriptors attached (from the header or
+/// inferred by the trace layer).
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct BlockTrace {
+    pub label: Czyx,
+    /// Count of each [`OpClass`] seen in the block (`OpClass::Any` unused).
+    pub class_counts: [u16; 20],
+    /// Behavior descriptors carried by / inferred for this block.
+    pub behavior: Behavior,
+}
+
+impl BlockTrace {
+    /// Build from a decoded code cell, deriving the op-class histogram and
+    /// reading any behavior descriptors from its header flags.
+    pub fn from_cell(cell: &CodeCell) -> BlockTrace {
+        let mut counts = [0u16; 20];
+        for op in &cell.code {
+            let c = OpClass::of(op) as usize;
+            if c < 20 {
+                counts[c] += 1;
+            }
+        }
+        BlockTrace {
+            label: cell.label,
+            class_counts: counts,
+            behavior: Behavior::from_flags(cell.header.flags.bits()),
+        }
+    }
+
+    /// Total op count.
+    pub fn total(&self) -> u32 {
+        self.class_counts.iter().map(|&c| c as u32).sum()
+    }
+}
+
+/// A higher-level classification of a block, inferred by [`BlockClassifier`].
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum BlockKind {
+    /// Mostly arithmetic/logic — a computation block.
+    Computation,
+    /// Dominated by control flow (jumps / comparisons) — a branch block.
+    Branch,
+    /// Contains call links to other records — a call/composition block.
+    CallTrampoline,
+    /// Heavy I/O or network descriptors — an I/O section.
+    IoSection,
+    /// Otherwise: a plain linear sequence.
+    Sequence,
+}
+
+/// Deterministic classifier: maps a [`BlockTrace`] to a [`BlockKind`] from its
+/// op-class histogram and behavior descriptors. (The transparent "model".)
+pub struct BlockClassifier;
+
+impl BlockClassifier {
+    pub fn classify(block: &BlockTrace) -> BlockKind {
+        let c = &block.class_counts;
+        let arith = c[OpClass::Add as usize]
+            + c[OpClass::Sub as usize]
+            + c[OpClass::Mul as usize]
+            + c[OpClass::Div as usize]
+            + c[OpClass::Mod as usize]
+            + c[OpClass::And as usize]
+            + c[OpClass::Or as usize]
+            + c[OpClass::Xor as usize]
+            + c[OpClass::Shl as usize]
+            + c[OpClass::Shr as usize];
+        let ctrl = c[OpClass::Eq as usize]
+            + c[OpClass::Ne as usize]
+            + c[OpClass::Lt as usize]
+            + c[OpClass::Gt as usize]
+            + c[OpClass::Le as usize]
+            + c[OpClass::Ge as usize];
+        let jumps = c[OpClass::Const as usize];
+        let calls = c[OpClass::CallLink as usize];
+
+        if block.behavior.0 & (Behavior::IO_HEAVY | Behavior::NETWORK) != 0 {
+            return BlockKind::IoSection;
+        }
+        if calls > 0 {
+            return BlockKind::CallTrampoline;
+        }
+        if ctrl > 0 && ctrl >= arith {
+            return BlockKind::Branch;
+        }
+        if arith > 0 {
+            return BlockKind::Computation;
+        }
+        // Fallback: anything with comparisons/jumps is a branch, else sequence.
+        if jumps > 0 || ctrl > 0 {
+            BlockKind::Branch
+        } else {
+            BlockKind::Sequence
+        }
+    }
+}
+
+/// Suggest transformations for a block, returning candidate [`TranslationRule`]s
+/// the DBT layer can apply (PDF: "suggest new code sequences or
+/// orchestrations"). Deterministic and local: each suggestion records *why*.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct Suggestion {
+    pub rule: TranslationRule,
+    pub rationale: String,
+}
+
+/// The AI runtime over a cube store: ingests traces, classifies, and suggests
+/// DBT rules. Writes suggested rules into the `c220` rule band via
+/// [`store_rule`] so `cubedbt::DbRuntime` can discover and apply them.
+pub struct CubeAi {
+    store: CubeStore<HashBackend>,
+    next_trace_x: u8,
+    next_rule_x: u8,
+}
+
+impl CubeAi {
+    /// Build an empty AI runtime over a fresh in-memory store.
+    pub fn new() -> Self {
+        CubeAi {
+            store: CubeStore::new(HashBackend::new()),
+            next_trace_x: 1,
+            next_rule_x: 1,
+        }
+    }
+
+    /// Ingest a captured trace (e.g. from `cubetrace`): store the block under
+    /// the `c230` trace band and return its coordinate.
+    pub fn ingest_trace(&mut self, block: &BlockTrace) -> Czyx {
+        let label = Czyx::new(C_TRACE, 1, 1, self.next_trace_x);
+        self.next_trace_x = self.next_trace_x.wrapping_add(1).max(1);
+        let mut h = CubeHeader::new();
+        h.title = Some(format!("trace:{:?}", block.label));
+        h.doc_type = Some(Kind::Other.as_str().into());
+        h.size_bytes = Some(block.class_counts.len() as u64 * 2);
+        h.flags.0 |= block.behavior.to_flags();
+        h.refresh_flags();
+        // Body: the raw histogram (20 x u16 le).
+        let mut body = Vec::with_capacity(40);
+        for c in &block.class_counts {
+            body.extend_from_slice(&c.to_le_bytes());
+        }
+        self.store.put_record(label, &h, &body);
+        label
+    }
+
+    /// Classify a single block.
+    pub fn classify(&self, block: &BlockTrace) -> BlockKind {
+        BlockClassifier::classify(block)
+    }
+
+    /// Produce suggestions for a block (does not yet persist them).
+    pub fn suggest(&self, block: &BlockTrace) -> Vec<Suggestion> {
+        let kind = BlockClassifier::classify(block);
+        let mut out = Vec::new();
+        match kind {
+            BlockKind::Computation => {
+                // Suggest vectorizing a repeated multiply-by-constant:
+                // Mul(const) -> Const(shift?), but keep it conservative:
+                // replace Mul with a left-shift when operand is a power of two.
+                out.push(Suggestion {
+                    rule: TranslationRule {
+                        name: format!("compute-opt:{:?}", block.label),
+                        target: OpClass::Mul,
+                        fragment: vec![Op::Shl],
+                    },
+                    rationale: "computation block: Mul may be replaced by Shl (power-of-two)".into(),
+                });
+            }
+            BlockKind::Branch => {
+                out.push(Suggestion {
+                    rule: TranslationRule {
+                        name: format!("branch-opt:{:?}", block.label),
+                        target: OpClass::Any,
+                        fragment: vec![Op::Nop],
+                    },
+                    rationale: "branch block: redundant ops may be collapsed to Nop".into(),
+                });
+            }
+            BlockKind::IoSection => {
+                out.push(Suggestion {
+                    rule: TranslationRule {
+                        name: format!("io-batch:{:?}", block.label),
+                        target: OpClass::CallLink,
+                        fragment: vec![Op::CallLink(0)],
+                    },
+                    rationale: "io section: calls may be coalesced via a batched variant".into(),
+                });
+            }
+            _ => {}
+        }
+        out
+    }
+
+    /// Ingest a block and persist its suggestions as DBT rules in the `c220`
+    /// band. Returns the stored rule coordinates (empty if no suggestions).
+    pub fn ingest_and_suggest(&mut self, block: &BlockTrace) -> Vec<Czyx> {
+        self.ingest_trace(block);
+        let sugs = self.suggest(block);
+        let mut coords = Vec::new();
+        for s in &sugs {
+            let c = store_rule(&mut self.store, &s.rule, self.next_rule_x);
+            self.next_rule_x = self.next_rule_x.wrapping_add(1).max(1);
+            coords.push(c);
+        }
+        coords
+    }
+
+    /// Borrow the backing store (e.g. to hand to `cubedbt::DbRuntime`).
+    pub fn store(&self) -> &CubeStore<HashBackend> {
+        &self.store
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use cubecode::opcode::Op;
+    use cubecoords::Czyx;
+
+    fn cell(coord: Czyx, code: Vec<Op>, beh: Behavior) -> CodeCell {
+        let mut h = CubeHeader::new();
+        h.title = Some("blk".into());
+        h.doc_type = Some(Kind::Fn.as_str().into());
+        h.flags.0 |= beh.to_flags();
+        h.refresh_flags();
+        CodeCell::from_record(coord, &h, &cubecode::opcode::encode(&code))
+            .expect("cell is valid bytecode")
+    }
+
+    #[test]
+    fn trace_classifies_computation() {
+        let c = cell(
+            Czyx::new(1, 1, 1, 1),
+            vec![Op::Const(3), Op::Const(4), Op::Mul, Op::Halt],
+            Behavior(Behavior::PURE),
+        );
+        let t = BlockTrace::from_cell(&c);
+        assert_eq!(BlockClassifier::classify(&t), BlockKind::Computation);
+        // total() sums op-class histogram; Halt maps to OpClass::Any (index 20,
+        // outside the [0..20) histogram), so 3 counted ops (Const, Const, Mul).
+        assert_eq!(t.total(), 3);
+    }
+
+    #[test]
+    fn trace_classifies_io_section() {
+        let c = cell(
+            Czyx::new(1, 1, 1, 2),
+            vec![Op::Const(1), Op::Halt],
+            Behavior(Behavior::IO_HEAVY | Behavior::NETWORK),
+        );
+        let t = BlockTrace::from_cell(&c);
+        assert_eq!(BlockClassifier::classify(&t), BlockKind::IoSection);
+    }
+
+    #[test]
+    fn trace_classifies_call_trampoline() {
+        let c = cell(
+            Czyx::new(1, 1, 1, 3),
+            vec![Op::CallLink(0), Op::CallLink(1), Op::Halt],
+            Behavior::default(),
+        );
+        let t = BlockTrace::from_cell(&c);
+        assert_eq!(BlockClassifier::classify(&t), BlockKind::CallTrampoline);
+    }
+
+    #[test]
+    fn suggest_emits_rule_and_persists() {
+        let c = cell(
+            Czyx::new(1, 1, 1, 4),
+            vec![Op::Const(3), Op::Const(4), Op::Mul, Op::Halt],
+            Behavior(Behavior::PURE),
+        );
+        let t = BlockTrace::from_cell(&c);
+        let mut ai = CubeAi::new();
+        let coords = ai.ingest_and_suggest(&t);
+        assert_eq!(coords.len(), 1, "computation block suggests one rule");
+        assert_eq!(coords[0].c, rule_band());
+        // The stored rule is discoverable by cubedbt.
+        let rt = cubedbt::DbRuntime::new(ai.store().clone());
+        assert_eq!(rt.discover_rules().len(), 1);
+    }
+
+    #[test]
+    fn ingest_trace_stores_under_c230() {
+        let c = cell(Czyx::new(1, 1, 1, 5), vec![Op::Halt], Behavior::default());
+        let t = BlockTrace::from_cell(&c);
+        let mut ai = CubeAi::new();
+        let coord = ai.ingest_trace(&t);
+        assert_eq!(coord.c, C_TRACE);
+    }
+
+    // Helper: the rule band constant lives in cubedbt; assert equality without
+    // importing the const name directly (kept local to the test).
+    fn rule_band() -> u8 {
+        cubedbt::C_DBT_RULE
+    }
+}
+
+