diff --git a/crates/ogar-loco/examples/funnel_probe.rs b/crates/ogar-loco/examples/funnel_probe.rs
new file mode 100644
index 0000000..ae8c65d
--- /dev/null
+++ b/crates/ogar-loco/examples/funnel_probe.rs
@@ -0,0 +1,193 @@
+//! PROBE-ORACLE-FUNNEL Stage 0 — does the funnel discriminate?
+//!
+//! Pre-registration: lance-graph `.claude/plans/oracle-funnel-probe-v1.md`
+//! (expectations E1–E4 written before this ran). Three deterministic
+//! generator arms bracket what an LLM could emit; the shipped gates
+//! (`validate` → `statement_bounds`) refuse or pass; `FunnelTally` (W-4)
+//! reports which gate fired. No LLM, no API, no new mints — the empty-domain
+//! blockly shared core only.
+//!
+//! Honest boundary: bodies are ≤16 calls under `LaneShape::Pairs` with
+//! single-byte immediates, so the body-ENTRY gate (`BodyError`) is
+//! structurally excluded here — Stage 0 exercises the segmentation gate.
+//!
+//! Run: `cargo run -p ogar-loco --example funnel_probe`
+
+use ogar_loco::statements::{StatementError, statement_bounds};
+use ogar_loco::telemetry::{FunnelTally, RefusalGate};
+use ogar_loco::vocabulary::conformance::validate;
+use ogar_loco::{Call, FnIndex, FunctionBody, LaneShape, Vocabulary};
+
+const N: usize = 1000;
+const MAX_LEN: u64 = 16;
+const SEED: u64 = 0x9E37_79B9_7F4A_7C15;
+
+/// SplitMix64 — the workspace's deterministic sampler (certification-officer
+/// convention). Zero-dep, bit-exact across runs.
+struct SplitMix64(u64);
+
+impl SplitMix64 {
+    fn next(&mut self) -> u64 {
+        self.0 = self.0.wrapping_add(0x9E37_79B9_7F4A_7C15);
+        let mut z = self.0;
+        z = (z ^ (z >> 30)).wrapping_mul(0xBF58_476D_1CE4_E5B9);
+        z = (z ^ (z >> 27)).wrapping_mul(0x94D0_49BB_1331_11EB);
+        z ^ (z >> 31)
+    }
+
+    /// Uniform in `0..bound` (modulo bias negligible at these bounds vs u64).
+    fn below(&mut self, bound: u64) -> u64 {
+        self.next() % bound
+    }
+}
+
+struct EmptyVocab;
+impl Vocabulary for EmptyVocab {
+    fn domain_stack_arity(&self, _f: FnIndex) -> Option<u8> {
+        None
+    }
+    fn domain_body_refs(&self, _f: FnIndex) -> u8 {
+        0
+    }
+}
+
+fn main() {
+    let checked = validate(EmptyVocab).expect("blockly shared core validates");
+    let table = checked.table();
+
+    // The segmentable set: slots declaring BOTH arity and pushes_result.
+    let segmentable: Vec<FnIndex> = (0..=u8::MAX)
+        .map(FnIndex)
+        .filter(|f| table.stack_arity(*f).is_some() && table.pushes_result(*f).is_some())
+        .collect();
+    println!("segmentable slots: {}", segmentable.len());
+
+    // ── Legend (the Stage-1 prompt anchor): named+covered slots only ──
+    let mut legend = String::new();
+    for f in (0..=u8::MAX).map(FnIndex) {
+        if let (Some(name), Some(arity), Some(pushes)) = (
+            table.spec(f).name,
+            table.stack_arity(f),
+            table.pushes_result(f),
+        ) {
+            legend.push_str(&format!(
+                "0x{:02X} {name} arity={arity} pushes={pushes}\n",
+                f.0
+            ));
+        }
+    }
+    let lines = legend.lines().count();
+    println!(
+        "legend: {} lines, {} bytes, ~{} tokens (bytes/4 estimate)\n",
+        lines,
+        legend.len(),
+        legend.len() / 4
+    );
+
+    type Gen = fn(&mut SplitMix64, &[FnIndex], &ogar_loco::VocabularyTable) -> Vec<Call>;
+    let arms: [(&str, Gen); 3] = [
+        ("R (floor: uniform bytes)", gen_uniform),
+        ("G (mid: legend-constrained)", gen_legend),
+        ("W (ceiling: stack-aware walk)", gen_walk),
+    ];
+
+    for (label, generate) in arms {
+        let mut rng = SplitMix64(SEED);
+        let mut tally = FunnelTally::default();
+        let mut stmt_counts: Vec<usize> = Vec::new();
+        for _ in 0..N {
+            let calls = generate(&mut rng, &segmentable, table);
+            let body = FunctionBody::from_calls(LaneShape::Pairs, &calls)
+                .expect("constructions stay inside the Pairs budget");
+            match statement_bounds(&checked, &body) {
+                Ok(stmts) => {
+                    tally.record(Ok(()));
+                    stmt_counts.push(stmts.len());
+                }
+                Err(e) => tally.record(Err(RefusalGate::from(&e))),
+            }
+        }
+        println!("arm {label}: {}/{} survived", tally.survived, tally.total());
+        for (gate, n) in tally.nonzero_gates() {
+            println!("  {gate:?}: {n}");
+        }
+        if !stmt_counts.is_empty() {
+            let sum: usize = stmt_counts.iter().sum();
+            let max = stmt_counts.iter().max().copied().unwrap_or(0);
+            println!(
+                "  survivor statements: mean {:.2}, max {max}",
+                sum as f64 / stmt_counts.len() as f64
+            );
+        }
+        println!();
+    }
+
+    // Two-sided check on the mapping itself: one known-refused body per gate
+    // must land on the RIGHT gate (the funnel's own can-it-fire test).
+    let checked2 = validate(EmptyVocab).unwrap();
+    let underflow = FunctionBody::from_calls(LaneShape::Pairs, &[Call::new(FnIndex::ADD)]).unwrap();
+    assert!(matches!(
+        statement_bounds(&checked2, &underflow),
+        Err(StatementError::StackUnderflow { .. })
+    ));
+    println!("gate-identity spot check: StackUnderflow lands on StackUnderflow — ok");
+}
+
+/// Arm R: every byte uniform — models an LLM that knows nothing.
+fn gen_uniform(
+    rng: &mut SplitMix64,
+    _seg: &[FnIndex],
+    _table: &ogar_loco::VocabularyTable,
+) -> Vec<Call> {
+    let len = 1 + rng.below(MAX_LEN) as usize;
+    (0..len)
+        .map(|_| Call::with_value(FnIndex(rng.below(256) as u8), rng.below(256) as u8))
+        .collect()
+}
+
+/// Arm G: calls uniform over the segmentable set — read the legend, not the
+/// grammar.
+fn gen_legend(
+    rng: &mut SplitMix64,
+    seg: &[FnIndex],
+    _table: &ogar_loco::VocabularyTable,
+) -> Vec<Call> {
+    let len = 1 + rng.below(MAX_LEN) as usize;
+    (0..len)
+        .map(|_| {
+            let f = seg[rng.below(seg.len() as u64) as usize];
+            Call::with_value(f, rng.below(256) as u8)
+        })
+        .collect()
+}
+
+/// Arm W: stack-aware — only calls whose arity fits the current depth; stops
+/// at a statement boundary (depth 0) or a single trailing value (depth 1).
+fn gen_walk(
+    rng: &mut SplitMix64,
+    seg: &[FnIndex],
+    table: &ogar_loco::VocabularyTable,
+) -> Vec<Call> {
+    let target = 1 + rng.below(MAX_LEN) as usize;
+    let mut calls = Vec::new();
+    let mut depth = 0usize;
+    while calls.len() < target || depth > 1 {
+        let eligible: Vec<FnIndex> = seg
+            .iter()
+            .copied()
+            .filter(|f| usize::from(table.stack_arity(*f).unwrap()) <= depth)
+            .collect();
+        let f = eligible[rng.below(eligible.len() as u64) as usize];
+        depth -= usize::from(table.stack_arity(f).unwrap());
+        if table.pushes_result(f).unwrap() {
+            depth += 1;
+        }
+        calls.push(Call::with_value(f, rng.below(256) as u8));
+        // Safety valve so a run of pushes can always be consumed within a
+        // bounded body: past the target, prefer any depth-reducing step.
+        if calls.len() > target + 32 {
+            break;
+        }
+    }
+    calls
+}
diff --git a/docs/BLOCK-EDITOR-PLAN.md b/docs/BLOCK-EDITOR-PLAN.md
index ab374ca..bfe55ce 100644
--- a/docs/BLOCK-EDITOR-PLAN.md
+++ b/docs/BLOCK-EDITOR-PLAN.md
@@ -721,3 +721,34 @@ All five landed; nothing on #241's gated list was touched.
 Open questions the handover left, both resolved here: **OQ-1** (name
 placement) → in `FnSpec`. **OQ-2** (144 shared slots = 144 rung-2 atoms) →
 left as recorded numerology; not addressed, not ruled on.
+
+## PROBE-ORACLE-FUNNEL Stage 0 — the funnel discriminates (measured, 2026-08-05)
+
+Harness: `crates/ogar-loco/examples/funnel_probe.rs` (deterministic, SplitMix64
+seed `0x9E3779B97F4A7C15`, N=1000/arm, Pairs, len 1..=16). Pre-registration
+with expectations E1–E4 written BEFORE the run lives consumer-side (lance-graph
+`.claude/plans/oracle-funnel-probe-v1.md`); the probe consumes only shipped
+gates — `validate` (W-1 path), `statement_bounds` (R5), `FunnelTally` (W-4),
+the empty-domain blockly core. No LLM, no API, no mints.
+
+Measured (all four pre-registered expectations met):
+
+| arm | model of the generator | survived | dominant refusal |
+|---|---|---|---|
+| R (floor) | uniform random bytes | 5/1000 (0.5%) | `StatementUncovered` 831 |
+| G (mid) | knows the legend, not the grammar | 25/1000 (2.5%) | `StatementUnderflow` 970 |
+| W (ceiling) | stack-aware walk | 1000/1000 (100%) | — (stmts mean 2.32, max 8) |
+
+- **E4 (the KILL) passes wide:** R↔W spread 99.5 points ≥ 50 — the
+  refuse-don't-guess firewall genuinely discriminates; an LLM arm (Stage 1,
+  consumer-side, gated) is justified on this vocabulary.
+- **The extra finding: the legend is not the grammar.** Arm G sits at the
+  floor (2.5% vs 0.5%), not midway — vocabulary knowledge buys almost
+  nothing; ~all constraint lives in the stack discipline. A Stage-1 prompt
+  must teach the postfix discipline, not merely list the table.
+- **Legend cost anchor:** 50 named+covered slots → 1531 bytes ≈ 382 tokens
+  (bytes/4 estimate) — negligible prompt overhead.
+- **Honest boundary:** bodies ≤16 calls / Pairs / single-byte immediates, so
+  `BodyError` (entry gate) is structurally unexercised; Stage 0 measures the
+  segmentation gate. `FunnelTally`'s gate-identity mapping spot-checked
+  (underflow lands on `StatementUnderflow`).