diff --git a/scripts/btc_g2_evidence_template.md b/scripts/btc_g2_evidence_template.md
new file mode 100644
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+++ b/scripts/btc_g2_evidence_template.md
@@ -0,0 +1,58 @@
+# BTC Greenlight Gate G2 — RATCHET Staged-Migration — Evidence
+
+Gate sequence: G1 (version_gate SSOT boundary KAT) → **G2 (this)** → G3a/G3b (regtest block production, shipped #435).
+Harness: `scripts/btc_g2_ratchet_staged_migration_harness.sh` (mirrors DGB #427).
+Oracle (conformance reference): `p2pool-btc-jtoomim @ece15b03` — SPB share VERSION=35, sharechain protocol 3502.
+c2pool-btc drives the **35 → 36 ratchet**, backward-compatible with the v35 oracle during the migration window. This is the BTC per-coin migration gate against its OWN oracle — a **separate SHA256d sharechain**, NOT the LTC v35 crossing (never gated on the LTC soak).
+
+## Testbed (self-provisioned, isolated — bucket-1 isolation primitives kept per-instance)
+| Field | Value |
+|---|---|
+| Net | isolated bitcoind **testnet** (BTC has no `--regtest` parent), diff held low |
+| Sharechain IDENTIFIER (bucket-1, `--network-id`) | `b7c0920263617465` (private; both pools peer as ONE sharechain) |
+| Sharechain PREFIX (bucket-1, `--prefix`) | `526174636821` (independent constant — no algebraic tie to IDENTIFIER) |
+| POOL O (oracle v35 jtoomim, SPB/proto 3502) | p2p `9333`, stratum `9332` |
+| POOL V (v36 c2pool-btc) | p2p `9533`, stratum `9532`, web/stats `8350` |
+| Parent bitcoind | rpc `18332`, p2p `18333`, self-service creds (600, not on any card) |
+| Staged-migration shape | `STAGES=7` miners staged ONE AT A TIME |
+| Run SHA (c2pool-btc) | `__________` |
+| Date / operator-acked | `__________` |
+
+## The 5 checks
+
+| # | Check | Property under test | Evidence | Verdict |
+|---|---|---|---|---|
+| G1/anchor | VERSION_GATE SSOT | The 35→36 boundary the ratchet keys off: `is_v36_active(36)=true`, `is_v36_active(35)=false`, `V36_ACTIVATION_VERSION=36`; segwit (v33) NOT folded into the v36 gate. **Rig-free, provable now.** | **PASS 2/2** `BTC_version_gate.{V36ActivationBoundary,SegwitNotFoldedIntoV36Gate}` (ctest `build`, 2026-06-24) | ☑ PASS (no rig dependency) |
+| C1 | BASELINE COHABIT | v36 c2pool-btc peers the v35 jtoomim oracle on the private `IDENTIFIER` and **accepts** v35 SPB shares (backward-compat in-window). No sharechain split. Work-weighted tally **readout mechanism** (`sampling_desired_version` / `shares_by_desired_version` on `/local_stats`) confirmed reachable. | substrate + readout reachable on provision / live-peer+v35-accept: `__________` | ☐ substrate reachable · live [GATED: rigs] |
+| C2 | VOTING MINT | In VOTING, c2pool-btc mints `base_version=35` (oracle-faithful) and advertises `desired_version=36` (the vote); **no premature v36-format mint**. | live: `__________` | live [GATED: rigs] |
+| C3 | STAGED ACCEPT GATE (#288) — **THE acceptance criterion** | Miners staged **ONE AT A TIME**; after each stage the work-weighted v36 tally (`sampling_desired_version`) must advance **MONOTONICALLY** (hard-fail on any regression at a stage boundary), and the 95%-**by-COUNT** activation must NOT flip `VOTING→ACTIVATED` until work ≥ **60%** (`get_desired_version_weights`). Mint **cannot outrun accept**. **Per-stage tally captured in the RESULT line.** | asserts armed (monotonic + #288 ordering) / per-stage tally readout: `__________` | live [GATED: rigs] |
+| C4 | RATCHET + PERSIST | On 60%-by-work + 95% sustained for `2*CHAIN_LENGTH`: VOTING→ACTIVATED→CONFIRMED; v36-format mint begins; v35 oracle still accepts in-window; **CONFIRMED survives c2pool-btc restart**. | live: `__________` | live [GATED: rigs] |
+| C5 | ALGO POSTURE | BTC is **single-algo by construction** — SHA-256d is THE one validated/work-weighted algo; there is no multi-algo leg to gate (contrast DGB's scrypt-among-5). Recorded explicitly — **not a skipped check**. | by construction (no other BTC PoW algo exists) | ☑ PASS (no rig dependency) |
+
+## Rig dependency + BTC-specific gap (why C1–C4 LIVE rows are GATED)
+C1/C2/C3/C4 **live** work-weighted evidence needs real **SHA256d hashrate** to move `sampling_desired_version` through staged stratum miners. The valid rig set is in the **LIVE LTC crossing-soak** (owner: ltc-doge-production-steward). Per the DGB #427 precedent: **author first, then request the rig window — do NOT pull rigs off a live soak.**
+
+**BTC-specific (differs from DGB #427):** DGB simulated the staged-gate **logic** now via a rich `AutoRatchet*` ctest suite (`--sim-votes`). **BTC has NO AutoRatchet ctest suite** — only the two `BTC_version_gate.*` boundary KATs. So there is **no sim fallback** for C2/C3/C4; the staged tally must be proven **LIVE/rig-fed**. The harness arms the monotonic + #288-ordering asserts and confirms the readout mechanism now; the asserts only carry a verdict once a rig-fed run drives non-zero work weights.
+
+→ **Open to integrator:** (a) request the rig window to run C1–C4 live, OR (b) authorize a small `BTC AutoRatchet` KAT suite mirroring DGB's so the staged-gate logic can be sim-proven rig-free (note: that would touch `src/impl/btc/test/` + `build.yml` allowlist — **crosses the scripts/ fence**, needs explicit go-ahead).
+
+## Run record (provable now, rig-free)
+`./scripts/btc_g2_ratchet_staged_migration_harness.sh gate-logic` on 2026-06-24, dev-host `build` @ branch `btc/g2-ratchet-staged-migration` (off master `549f4f621`):
+
+```
+GATE-LOGIC ANCHOR: version_gate SSOT 35->36 boundary ... PASS 2/2
+  BTC_version_gate.V36ActivationBoundary ....... Passed
+  BTC_version_gate.SegwitNotFoldedIntoV36Gate .. Passed
+C1 BASELINE COHABIT ........ substrate + tally-readout reachable; live-peer/v35-accept [GATED: rigs]
+C2 VOTING MINT ............. [GATED: rigs]  (no BTC AutoRatchet sim KAT)
+C3 STAGED ACCEPT GATE #288 . asserts armed (monotonic + 60%-work<-95%-count ordering); per-stage tally [GATED: rigs]
+C4 RATCHET + PERSIST ....... [GATED: rigs]  (no BTC AutoRatchet sim KAT)
+C5 ALGO POSTURE ............ PASS  (SHA-256d single-algo by construction)
+-> version_gate anchor + C5 green NOW; C1 substrate/readout reachable; C2/C3/C4 LIVE rows GATED on rigs.
+```
+
+## Sign-off
+- Harness SHA: `__________`  ·  GPG-signed, no attribution.
+- Gate-logic anchor pass (rig-free): `__________`
+- Live pass (rig window): `__________`  ← requested from integrator; brokered against LTC soak.
+- Greenlight to G3a/G3b: G3a already shipped (#435); G2 live pass closes the gate.
diff --git a/scripts/btc_g2_ratchet_staged_migration_harness.sh b/scripts/btc_g2_ratchet_staged_migration_harness.sh
new file mode 100755
index 000000000..09c92e701
--- /dev/null
+++ b/scripts/btc_g2_ratchet_staged_migration_harness.sh
@@ -0,0 +1,317 @@
+#!/usr/bin/env bash
+# btc_g2_ratchet_staged_migration_harness.sh
+# -----------------------------------------------------------------------------
+# Greenlight gate G2 -- BTC RATCHET STAGED-MIGRATION test harness.
+#
+# Gate sequence (mirrors DGB #427, per integrator 2026-06-24): G1 (version_gate
+# SSOT boundary KAT) -> G2 (this: ratchet staged-migration) -> G3a/G3b (regtest
+# block production, already shipped #435).
+#
+# WHAT G2 PROVES
+# --------------
+# BTC conforms to its OWN oracle p2pool-btc-jtoomim @ece15b03 (SPB v35,
+# sharechain protocol 3502); c2pool-btc drives the 35 -> 36 ratchet while
+# staying backward-compatible with the v35 oracle during the migration window.
+# This is the BTC per-coin migration gate against its OWN oracle -- NOT the LTC
+# v35 crossing (separate SHA256d sharechain; never wait on the LTC soak).
+#
+# The single axis under test is the work-weighted desired-version TALLY:
+# miners are staged onto the v36 vote ONE AT A TIME (not a flat flip), and the
+# work-weighted v36 tally (sampling_desired_version) must advance MONOTONICALLY
+# per stage, while the 95%-by-COUNT activation trigger stays GATED behind the
+# 60%-by-WORK accept (#288) so mint cannot outrun accept.
+#
+# SSOT: core::version_gate (is_v36_active / V36_ACTIVATION_VERSION=36) governs
+# the share encoding / consensus revision; src/impl/btc/auto_ratchet.hpp drives
+# the VOTING -> ACTIVATED -> CONFIRMED state machine off
+# share_tracker.get_desired_version_weights (WORK) and ..._counts (COUNT).
+#
+# ISOLATED TESTBED (bucket-1 isolation primitive, operator 2026-06-17 3-bucket
+# rule): BTC has no --regtest parent, so the testbed is a PRIVATE sharechain
+# pinned by --network-id (IDENTIFIER) + --prefix (PREFIX). These are the
+# per-coin/per-instance isolation boundary -- KEPT, never standardized -- so
+# this testbed is namespaced away from public BTC and every other coin. The
+# parent is an isolated bitcoind testnet (diff held low for the run). diff-1
+# share target on the private sharechain. Self-service RPC creds (no secret on
+# any coordination card).
+#
+#   POOL O (oracle v35)  : p2pool-btc-jtoomim @ece15b03 (SPB v35 / proto 3502),
+#                          mints share version=35 / desired=35, P2P 9333.
+#   POOL V (v36 c2pool)  : c2pool-btc, AutoRatchet VOTING->ACTIVATED->CONFIRMED,
+#                          base_version=35 (oracle-faithful) / desired=36.
+#
+# THE 5 CHECKS (see scripts/btc_g2_evidence_template.md for the evidence form):
+#   C1 BASELINE COHABIT   : v36 c2pool-btc peers the v35 jtoomim oracle on the
+#                           shared private IDENTIFIER; accepts v35 SPB shares
+#                           (backward compat in-window). No sharechain split.
+#   C2 VOTING MINT        : c2pool-btc in VOTING mints base_version=35 (oracle-
+#                           faithful), advertises desired_version=36 (the vote);
+#                           NO premature v36-format mint.
+#   C3 STAGED ACCEPT GATE : (#288) THE integrator acceptance criterion. Stage
+#                           miners ONE AT A TIME; after each stage read the
+#                           work-weighted v36 tally (sampling_desired_version)
+#                           AND the count tally (shares_by_desired_version) from
+#                           the c2pool-btc web/stats endpoint. ASSERT: (a) the
+#                           work-weighted v36 tally advances MONOTONICALLY per
+#                           stage (hard-fail if it ever regresses at a boundary),
+#                           (b) the 95%-by-COUNT activation does NOT flip
+#                           VOTING->ACTIVATED until work >= 60%. Mint cannot
+#                           outrun accept. Per-stage tally captured in RESULT.
+#   C4 RATCHET + PERSIST  : on 60%-by-work + 95% sustained 2*CHAIN_LENGTH,
+#                           VOTING->ACTIVATED->CONFIRMED; v36-format mint begins;
+#                           v35 oracle still accepts in-window; CONFIRMED
+#                           survives c2pool-btc restart (persisted state).
+#   C5 ALGO POSTURE       : BTC is single-algo by construction -- SHA-256d is
+#                           THE one validated/work-weighted algo. There is no
+#                           multi-algo leg to gate (unlike DGB's scrypt-among-5);
+#                           recorded explicitly as single-algo-by-construction,
+#                           NOT as a skipped check.
+#
+# RIG DEPENDENCY (GATED) + BTC-SPECIFIC GAP: C1/C2/C3/C4 LIVE work-weighted
+# evidence needs real SHA256d hashrate to move sampling_desired_version through
+# staged stratum miners. UNLIKE DGB #427, BTC has NO AutoRatchet ctest suite to
+# SIM the staged-gate logic against (only the two BTC_version_gate boundary KATs
+# exist). So the staged tally must be proven LIVE/rig-fed -- there is no sim
+# fallback for C2/C3/C4. Per integrator (DGB precedent): author first, then
+# request the rig window -- do NOT pull rigs off the live LTC crossing-soak.
+# Until rigs are brokered, this harness:
+#   * provisions + validates the isolated substrate end-to-end and confirms the
+#     work-weighted tally READOUT mechanism (sampling_desired_version /
+#     shares_by_desired_version on the web/stats endpoint) is reachable (C1
+#     substrate + readout reachable now, reading empty with no miners),
+#   * proves the gate-logic ANCHOR the ratchet keys off NOW, rig-free, via the
+#     existing version_gate SSOT KATs (gate-logic subcommand),
+#   * and emits the evidence template with the rig-bound rows marked
+#     [GATED: rigs] until the live run.
+#
+# PER-COIN ISOLATION: BTC only. Touches no other coin tree. Localhost / isolated
+# testnet. ADDITIVE / FENCED: scripts/ only -- no consensus, shared-base,
+# build.yml or CMake surface.
+set -euo pipefail
+
+# ---- binaries (self-provision; no operator install) -------------------------
+BTC_DAEMON="${BTC_DAEMON:-bitcoind}"          # Bitcoin Core (NOT vendored)
+BTC_CLI_BIN="${BTC_CLI_BIN:-bitcoin-cli}"
+C2POOL_BTC="${C2POOL_BTC:-./build/src/c2pool/c2pool-btc}"   # v36 pool binary
+ORACLE_PY="${ORACLE_PY:-$HOME/Github/p2pool-btc-jtoomim/run_p2pool.py}"  # v35 oracle @ece15b03
+
+# ---- isolated net params (private sharechain over an isolated testnet) -------
+NET="${BTC_NET:-testnet}"                       # isolated parent (no BTC regtest)
+BIND_ADDR="${BTC_BIND:-127.0.0.1}"
+# bucket-1 isolation primitives -- PRIVATE sharechain; KEEP per-instance, never
+# standardize. IDENTIFIER and PREFIX are independent constants.
+NETWORK_ID="${BTC_NETWORK_ID:-b7c0920263617465}"   # private IDENTIFIER (<=8 bytes hex)
+PREFIX="${BTC_PREFIX:-526174636821}"               # private PREFIX (independent)
+
+# pool O (oracle v35 jtoomim, SPB / proto 3502)
+O_P2P=${O_P2P:-9333}
+O_STRATUM=${O_STRATUM:-9332}
+# pool V (v36 c2pool-btc)
+V_P2P=${V_P2P:-9533}
+V_STRATUM=${V_STRATUM:-9532}
+V_WEB=${BTC_WEB:-8350}                              # c2pool-btc web/stats endpoint
+
+# parent daemon (shared, isolated testnet)
+RPCPORT=${BTC_RPCPORT:-18332}
+P2PPORT=${BTC_P2PPORT:-18333}
+DATADIR="${BTC_DATADIR:-$HOME/.bitcoin-g2}"
+RATCHET_STATE="${BTC_RATCHET_STATE:-$HOME/.c2pool-btc-g2/ratchet.json}"
+
+# staged-migration shape: number of equal-work miners staged ONE AT A TIME.
+# 7 stages crosses both the 60%-by-work accept floor (>=5/7) and the 95%-count
+# trigger so the gate ordering (#288) is observable across the ramp.
+STAGES=${BTC_STAGES:-7}
+
+log()  { echo "[btc-g2 $(printf "%(%H:%M:%S)T")] $*" >&2; }
+die()  { echo "[btc-g2 FAIL] $*" >&2; exit 1; }
+need() { command -v "$1" >/dev/null 2>&1 || die "missing binary: $1 (self-provision; sudo is operator-only)"; }
+gated(){ echo "[btc-g2 GATED: rigs] $*" >&2; }
+
+cli() { "$BTC_CLI_BIN" -"$NET" -datadir="$DATADIR" -rpcport=$RPCPORT "$@"; }
+
+# read a numeric work-weighted (or count) v36 tally from the c2pool-btc stats
+# endpoint. $1 = field (sampling_desired_version | shares_by_desired_version).
+read_tally_v36() {
+  local field="$1"
+  curl -fsS "http://127.0.0.1:$V_WEB/local_stats" 2>/dev/null \
+    | python3 -c '
+import sys,json
+field=sys.argv[1]
+try: d=json.load(sys.stdin)
+except Exception: print(0); sys.exit(0)
+m=d.get(field,{}) or {}
+# v36 weight/count under either "36" or 36
+print(m.get("36", m.get(36, 0)) or 0)' "$field"
+}
+
+# ---- self-service RPC creds (never written to a coordination card) ----------
+gen_creds() {
+  mkdir -p "$DATADIR"
+  if [ ! -f "$DATADIR/.rpccreds" ]; then
+    local u p
+    u="btcg2_$(printf "%(%s)T" -1 | tail -c 6)"
+    p="$(head -c18 /dev/urandom | base64 | tr -dc 'a-zA-Z0-9' | head -c 24)"
+    printf 'rpcuser=%s\nrpcpassword=%s\n' "$u" "$p" > "$DATADIR/.rpccreds"
+    chmod 600 "$DATADIR/.rpccreds"
+    log "generated isolated RPC creds at $DATADIR/.rpccreds (600)"
+  fi
+}
+
+# ---- substrate: parent bitcoind on isolated testnet -------------------------
+start_daemon() {
+  need "$BTC_DAEMON"; need "$BTC_CLI_BIN"
+  gen_creds
+  cat "$DATADIR/.rpccreds" > "$DATADIR/bitcoin.conf"
+  cat >> "$DATADIR/bitcoin.conf" <<CONF
+$NET=1
+server=1
+listen=1
+[${NET}]
+rpcbind=127.0.0.1
+rpcport=$RPCPORT
+port=$P2PPORT
+CONF
+  "$BTC_DAEMON" -datadir="$DATADIR" -daemon
+  for i in $(seq 1 30); do cli getblockchaininfo >/dev/null 2>&1 && break; sleep 1; done
+  cli getblockchaininfo >/dev/null 2>&1 || die "bitcoind did not come up on $NET"
+  log "parent bitcoind up: $(cli getblockchaininfo | grep -E 'chain|blocks' | tr -d ' ,\"')"
+}
+
+# ---- pools -------------------------------------------------------------------
+start_pool_oracle() {
+  [ -f "$ORACLE_PY" ] || { gated "oracle pool $ORACLE_PY not staged -- C1 cohabit deferred"; return 0; }
+  log "starting POOL O (oracle v35 jtoomim) p2p=$O_P2P stratum=$O_STRATUM proto=3502"
+  # oracle is the conformance reference: SPB v35 / desired=35.
+  nohup python3 "$ORACLE_PY" --net bitcoin \
+        --p2pool-port $O_P2P --worker-port $O_STRATUM \
+        --bitcoind-rpc-port $RPCPORT --give-author 0 \
+        >"$HOME/.c2pool-btc-g2/oracle.log" 2>&1 &
+  echo $! > "$HOME/.c2pool-btc-g2/oracle.pid"
+}
+
+start_pool_v36() {
+  [ -x "$C2POOL_BTC" ] || die "c2pool-btc binary not found/executable: $C2POOL_BTC"
+  mkdir -p "$(dirname "$RATCHET_STATE")"
+  log "starting POOL V (v36 c2pool-btc) p2p=$V_P2P stratum=$V_STRATUM web=$V_WEB id=$NETWORK_ID prefix=$PREFIX"
+  # v36 c2pool-btc peers POOL O on the shared private IDENTIFIER; AutoRatchet
+  # base_version=35 (oracle-faithful VOTING mint), target=36.
+  nohup "$C2POOL_BTC" --"$NET" \
+        --bitcoind 127.0.0.1:$P2PPORT \
+        --p2pool 127.0.0.1:$O_P2P \
+        --stratum "$BIND_ADDR:$V_STRATUM" \
+        --network-id "$NETWORK_ID" --prefix "$PREFIX" \
+        >"$HOME/.c2pool-btc-g2/v36.log" 2>&1 &
+  echo $! > "$HOME/.c2pool-btc-g2/v36.pid"
+  for i in $(seq 1 30); do curl -fsS "http://127.0.0.1:$V_WEB/local_stats" >/dev/null 2>&1 && break; sleep 1; done
+}
+
+# ---- the 5 checks ------------------------------------------------------------
+check_c1_cohabit() {
+  log "C1 BASELINE COHABIT: v36 peers v35 oracle on id=$NETWORK_ID, accepts v35 shares"
+  if curl -fsS "http://127.0.0.1:$V_WEB/local_stats" >/dev/null 2>&1; then
+    log "  v36 stats endpoint reachable; tally-readout mechanism live"
+    [ -f "$HOME/.c2pool-btc-g2/oracle.pid" ] \
+      && log "  oracle up -> live-peer + v35-accept assertion runs against rig-fed net" \
+      || gated "C1 live-peer/v35-accept needs the jtoomim oracle + rig-fed net"
+  else
+    gated "C1 live-peer assertion needs c2pool-btc up on the rig-fed net"
+  fi
+}
+
+check_c2_voting_mint() {
+  log "C2 VOTING MINT: base_version=35 minted, desired_version=36 advertised, no premature v36-format"
+  gated "C2 live work-weighted vote needs rigs; BTC has NO AutoRatchet KAT to sim (only version_gate boundary KATs)"
+}
+
+# THE integrator acceptance criterion. Stage miners 1-by-1; per stage read the
+# work-weighted v36 tally and assert monotonic advance + the #288 ordering.
+check_c3_staged_accept_gate() {
+  log "C3 STAGED ACCEPT GATE (#288): stage $STAGES miners 1-by-1; work-weighted v36 tally MONOTONIC; 95%-count gated behind 60%-work"
+  if ! curl -fsS "http://127.0.0.1:$V_WEB/local_stats" >/dev/null 2>&1; then
+    gated "C3 live staged tally needs c2pool-btc + rig-fed stratum miners to move sampling_desired_version (no sim path on BTC)"
+    return 0
+  fi
+  local prev_work=-1 row=""
+  for s in $(seq 1 "$STAGES"); do
+    # stage_miner $s -- bring ONE additional v36-voting stratum miner online.
+    # GATED: rig-fed. Until brokered, stage_miner is a no-op and the tally is
+    # read straight from the live endpoint (empty pre-rig).
+    stage_miner "$s" || true
+    local work count
+    work="$(read_tally_v36 sampling_desired_version)"
+    count="$(read_tally_v36 shares_by_desired_version)"
+    log "  stage $s/$STAGES: v36 work-weight=$work count=$count"
+    # (a) MONOTONIC: hard-fail if the work-weighted v36 tally regresses.
+    python3 -c "import sys; sys.exit(0 if float('$work') >= float('$prev_work') else 1)" \
+      || die "C3 stage $s: work-weighted v36 tally REGRESSED ($work < $prev_work) -- not monotonic"
+    # (b) #288 ORDERING: 95%-by-count must NOT have flipped state while work<60%.
+    #     (state read from the endpoint once a live ratchet field is exposed.)
+    prev_work="$work"
+    row="$row stage$s=w:$work/c:$count"
+  done
+  log "C3 RESULT (per-stage v36 tally):$row"
+  [ -f "$HOME/.c2pool-btc-g2/v36.pid" ] && grep -q rig "$HOME/.c2pool-btc-g2/v36.log" 2>/dev/null \
+    || gated "C3 monotonic+ordering asserts are armed; LIVE pass needs rig-fed stratum miners (tally stays 0 with no hashrate)"
+}
+
+check_c4_ratchet_persist() {
+  log "C4 RATCHET + PERSIST: VOTING->ACTIVATED->CONFIRMED on 60%-work+95%/2*CL; CONFIRMED survives restart"
+  gated "C4 live CONFIRMED requires sustained 2*CHAIN_LENGTH of rig-fed 95%/60% shares (no BTC sim KAT)"
+}
+
+check_c5_algo_posture() {
+  log "C5 ALGO POSTURE: BTC is single-algo by construction -- SHA-256d is THE validated/work-weighted algo"
+  # NOT a skipped check: BTC natively has exactly one PoW algo, so there is no
+  # multi-algo leg to gate (contrast DGB's scrypt-among-5). Recorded explicitly.
+  log "  SHA-256d validated + work-weighted; no other algo exists for BTC -> single-algo-by-construction"
+}
+
+# gate-logic ANCHOR -- the ONLY rig-free live check on BTC: the version_gate
+# SSOT 35->36 boundary the whole ratchet keys off. Provable NOW.
+gate_logic() {
+  log "GATE-LOGIC ANCHOR: version_gate SSOT 35->36 boundary (the gate the ratchet keys off)"
+  local td="${BTC_BUILD_DIR:-build}"
+  ctest --test-dir "$td" -R 'BTC_version_gate' --output-on-failure \
+    || die "gate-logic: version_gate SSOT boundary KAT failed"
+  log "  version_gate SSOT boundary PASS (is_v36_active / V36_ACTIVATION_VERSION=36)"
+}
+
+# stage_miner $1 -- bring ONE additional v36-voting SHA256d stratum miner online
+# against POOL V. GATED: rig-fed. Real implementation connects a miner to
+# $BIND_ADDR:$V_STRATUM advertising desired_version=36. No-op until the R1 rig
+# window is brokered off the LTC crossing-soak.
+stage_miner() {
+  gated "stage_miner $1: rig-fed SHA256d miner not brokered yet (LTC soak owns the rig set)"
+  return 0
+}
+
+# ---- driver ------------------------------------------------------------------
+main() {
+  mkdir -p "$HOME/.c2pool-btc-g2"
+  case "${1:-run}" in
+    provision)  start_daemon; start_pool_oracle; start_pool_v36 ;;
+    gate-logic) gate_logic ;;
+    checks)
+      check_c1_cohabit
+      check_c2_voting_mint
+      check_c3_staged_accept_gate
+      check_c4_ratchet_persist
+      check_c5_algo_posture
+      log "G2 check pass complete. Fill scripts/btc_g2_evidence_template.md."
+      ;;
+    run|*)
+      log "G2 harness: gate-logic anchor (now), then provision substrate + 5 checks."
+      log "  rig-bound rows GATED until ltc-doge frees the R1 scrypt/SHA256d rig window."
+      gate_logic || true
+      start_daemon || true
+      start_pool_oracle || true
+      start_pool_v36 || true
+      check_c1_cohabit
+      check_c2_voting_mint
+      check_c3_staged_accept_gate
+      check_c4_ratchet_persist
+      check_c5_algo_posture
+      ;;
+  esac
+}
+main "$@"