CHARAT-0: withdraw unsound ASCII cache; enroll Unicode char_at witness

dag/test/claim/char_at_unicode_witness_test.dag

@@ -0,0 +1,25 @@
+module test.claim.char_at_unicode_witness
+
+data live_tree_disposition: LiveTreeDisposition = SubstrateInputsOnly
+
+data char_at_unicode_witness_note: String = "CHARAT-0 discriminating control: char_at indexes Unicode code points, not UTF-8 bytes. A byte-offset implementation returns the wrong character at index 1 on \"aéb\" (continuation byte U+00A9 misread as ©) while code-point indexing returns U+00E9."
+
+fn ae_b_sample() -> String {
+  concat("a", concat(from_code_point(cp: 233), "b"))
+}
+
+test fn char_at_indexes_code_points_on_multibyte_text() -> Bool {
+  let s = ae_b_sample()
+  char_at(s: s, pos: 0) == "a"
+    && code_point(c: char_at(s: s, pos: 1)) == 233
+    && char_at(s: s, pos: 2) == "b"
+}
+
+test fn char_at_byte_offset_would_mismatch_at_index_one() -> Bool {
+  let s = ae_b_sample()
+  code_point(c: char_at(s: s, pos: 1)) != code_point(c: "©")
+}
+
+test fn string_length_counts_code_points_not_bytes() -> Bool {
+  string_length(s: ae_b_sample()) == 3
+}

scripts/run-charat0-json-scaling.sh

@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+# SCAFFOLD — CHARAT-0 parse_json survival slope comparison beside json_parse_scaling_probe
+# (not a general scripts/ home; same transport class as docs/probes/run_frontier_probe_survey_per_module.sh).
+# dissolve-on: delete when CHARAT-0 string-indexing acceptance enrolls a floor witness,
+# STR-RC-0 scaffold retires, or large-regime measurement refutes and the branch reverts.
+# Runtime-present: invokes json_parse_scaling_probe seed bin with JSON_PARSE_PROBE_MODE=survival
+# per (carrier, size) in a fresh process; compares origin/main interpreter vs dispatch HEAD.
+set -euo pipefail
+
+ROOT="$(git rev-parse --show-toplevel)"
+cd "$ROOT"
+
+PRE_DIR="/tmp/charat0-main-measure"
+SIZES=(20000 40000 80000)
+TIMEOUT_SEC=600
+
+termination_label() {
+  local ec="$1"
+  case "$ec" in
+    0) echo "completed" ;;
+    2) echo "parse_failed" ;;
+    137|134|9) echo "killed (OOM or signal)" ;;
+    124) echo "timeout" ;;
+    *) echo "failed" ;;
+  esac
+}
+
+git fetch origin main --depth=1
+MAIN_REF="origin/main"
+
+echo "# charat0_scaling head=$(git rev-parse HEAD)"
+echo "# charat0_scaling main=$(git rev-parse "$MAIN_REF")"
+
+cargo build --release -p v1-compiler --bin json_parse_scaling_probe
+POST_BIN="$ROOT/target/release/json_parse_scaling_probe"
+
+rm -rf "$PRE_DIR"
+git worktree remove --force "$PRE_DIR" 2>/dev/null || true
+git worktree prune 2>/dev/null || true
+git worktree add --detach "$PRE_DIR" "$MAIN_REF"
+PROBE_SRC="$ROOT/src/v1/stage0/src/bin/json_parse_scaling_probe.rs"
+cp "$PROBE_SRC" "$PRE_DIR/src/v1/stage0/src/bin/json_parse_scaling_probe.rs"
+if ! grep -q json_parse_scaling_probe "$PRE_DIR/src/v1/stage0/Cargo.toml"; then
+  cat >>"$PRE_DIR/src/v1/stage0/Cargo.toml" <<'EOF'
+
+# SCAFFOLD — CHARAT-0 / STR-RC-0 measurement transport (not floor-enrolled).
+# dissolve-on: enrolled witness or refuted hypothesis (see json_parse_scaling_probe.rs marker).
+[[bin]]
+name = "json_parse_scaling_probe"
+path = "src/bin/json_parse_scaling_probe.rs"
+EOF
+fi
+(
+  cd "$PRE_DIR"
+  CARGO_TARGET_DIR="$PRE_DIR/target" cargo build --release -p v1-compiler --bin json_parse_scaling_probe
+)
+PRE_BIN="$PRE_DIR/target/release/json_parse_scaling_probe"
+
+run_one() {
+  local label="$1"
+  local bin="$2"
+  local size="$3"
+  echo "=== $label target_bytes=$size (fresh process) ==="
+  set +e
+  timeout "$TIMEOUT_SEC" env \
+    JSON_PARSE_PROBE_MODE=survival \
+    JSON_PARSE_TARGET_BYTES="$size" \
+    "$bin"
+  local ec=$?
+  set -e
+  echo "# exit_code=$ec"
+  echo "# termination=$(termination_label "$ec")"
+  if [ "$ec" -ne 0 ]; then
+    echo "probe_refused label=$label target_bytes=$size exit_code=$ec termination=$(termination_label "$ec")" >&2
+    exit "$ec"
+  fi
+}
+
+echo "label\ttarget_bytes\telapsed_ms\tmembers_found\toutcome"
+for size in "${SIZES[@]}"; do
+  run_one "pre-main" "$PRE_BIN" "$size"
+  run_one "post-charat" "$POST_BIN" "$size"
+done

src/v1/stage0/Cargo.toml

@@ -78,6 +78,17 @@ path = "src/bin/claim_batch.rs"
 name = "claim_executor"
 path = "src/bin/claim_executor.rs"
 
+# CHARAT-0 / STR-RC-0 measurement scaffold (not floor-enrolled).
+# Local transport for `extdeps.languages.json.parse` `parse_json` interpreter scaling.
+# Modes: `scaling` (sub-40KB grid), `large` (100/200/507KB decisive regime), plus
+# `survival` and `memo_receipt` for mechanism receipts.
+# DISSOLUTION: delete when CHARAT-0 string-indexing acceptance enrolls a floor witness
+# (or STR-RC-0 scaffold retires), or when large-regime measurement refutes and reverts.
+# Carrier: `JSON_PARSE_SCALING_PROBE_SCAFFOLD_MARKER` in json_parse_scaling_probe.rs.
+[[bin]]
+name = "json_parse_scaling_probe"
+path = "src/bin/json_parse_scaling_probe.rs"
+
 # Resolved-type owned-data discovery for Consolidation #4553 glob discovery.
 # Hand-written CI tool (like claim_batch); exposes neutral decl facts only.
 [[bin]]
@@ -276,17 +287,6 @@ path = "src/bin/compile_clean_diagnostic_histogram.rs"
 name = "compile_clean_unlisted_import_census"
 path = "src/bin/compile_clean_unlisted_import_census.rs"
 
-# SCAFFOLD (DESIGN §7 seed-retained HAND-RUST / STR-RC-0) — local measurement transport
-# for `extdeps.languages.json.parse` `parse_json` interpreter scaling. NOT floor-enrolled.
-# Modes: `scaling` (sub-40KB grid, fixed-cost dominated) and `large` (100/200/507KB
-# decisive regime — post must survive sizes pre reportedly OOM'd on, or refute).
-# CHECKABLE RECEIPT: large-mode TSV rows `ok` vs host kill; not a sub-40KB exponent claim.
-# DISSOLUTION: delete when STR-RC-0 enrolls a floor witness or large-regime refutes and reverts.
-# Carrier: `JSON_PARSE_SCALING_PROBE_SCAFFOLD_MARKER` in json_parse_scaling_probe.rs.
-[[bin]]
-name = "json_parse_scaling_probe"
-path = "src/bin/json_parse_scaling_probe.rs"
-
 # B0 control witness (#7943, review 49798 / operator ruling): proves the
 # GENERATED stage0 realization of declaration_exposure_from_containment under
 # NamespaceStructuralRootExposure dispatches to three distinct outcomes

src/v1/stage0/src/bin/json_parse_scaling_probe.rs

@@ -1,6 +1,6 @@
 #![allow(clippy::disallowed_macros)]
 
-//! SCAFFOLD (DESIGN §7 seed-retained HAND-RUST / STR-RC-0) — host transport for
+//! SCAFFOLD (DESIGN §7 seed-retained HAND-RUST / CHARAT-0, STR-RC-0) — host transport for
 //! `parse_json` survival and mechanism measurements on the v1 interpreter.
 //!
 //! NOT floor-enrolled — run standalone via `cargo run --release -p v1-compiler --bin
@@ -11,13 +11,14 @@
 //!
 //! CHECKABLE RECEIPT: survival mode records Present parse + member count vs process death.
 //!
-//! DISSOLUTION: delete this bin when STR-RC-0 acceptance is floor-enrolled with a modeled
-//! witness, or when large-regime measurement refutes the hypothesis and the branch reverts.
+//! DISSOLUTION: delete this bin when CHARAT-0 string-indexing acceptance is floor-enrolled
+//! with a modeled witness (or STR-RC-0 scaffold retires), or when large-regime measurement
+//! refutes the hypothesis and the branch reverts.
 //! Receipt: `rg JSON_PARSE_SCALING_PROBE_SCAFFOLD_MARKER src/v1/stage0` until deletion.
 
 /// Grep receipt for scaffold dissolution (`rg JSON_PARSE_SCALING_PROBE_SCAFFOLD_MARKER`).
 pub const JSON_PARSE_SCALING_PROBE_SCAFFOLD_MARKER: &str =
-    "STR-RC-0 json_parse_scaling_probe measurement transport (not floor-enrolled)";
+    "CHARAT-0 STR-RC-0 json_parse_scaling_probe measurement transport (not floor-enrolled)";
 
 use std::process::ExitCode;
 use std::time::Instant;