core+gui+cli: anticipation/rebuild dates, preserve relative settings

Fixes around the delivery/build/check date handling (karen7 regtest):

- build_will (GUI + CLI) re-anchors date_to_check to the CURRENT heirs'
  earliest future delivery before building, so an anticipated rebuild is no
  longer blocked by the stale old-will anchor (NO_FUTURE_DATE). The checks of
  the existing will keep their anchored date_to_check.
- _sync_locktime_to_built_txs now PRESERVES RELATIVE locktime/threshold
  recipes ("2y"/"150d") in WILL_SETTINGS instead of freezing them to absolute
  timestamps: the anchored comparisons (resolve_locktime_against_tx and
  resolve_date_to_check with built_locktime) already prevent the daily
  invalidate prompt. Absolute values still sync on a genuine automatic
  anticipation.
- Will.remove_stale_wallet_history drops stale wallet-LOCAL will placeholders
  before every (re)build in GUI and CLI so their coins are available again.
- check_willexecutors_and_heirs raises HeirNotFoundException outside the
  count_heirs gate: a shortened relative recipe on a signed will now triggers
  a plain rebuild ("no heirs" only when there really are none).
- is_locktime_below_threshold compares the settings on one reference frame
  (resolve_guard_threshold), no longer against the built-will anchor.

Tests: purge unit + call-site, no-heirs, guard, anticipated-rebuild
end-to-end (GUI) + CLI mirror + fixed_percent_lists_amount unit,
relative-preserve sync; conftest restores electrum.constants.net after each
test (cross-file pollution guard).

bal/core/checkalive.py

@@ -96,6 +96,54 @@ def resolve_date_to_check(
     return threshold.to_timestamp()
 
 
+def resolve_guard_threshold(
+    is_basic_mode: bool,
+    will_settings: Any,
+    now: float | None = None,
+) -> float | None:
+    """Resolve the "locktime is lower than threshold" guard's reference.
+
+    The guard compares the stored settings on ONE reference frame: the
+    delivery (``locktime``, kept as at the call site) against this threshold.
+
+    Unlike :func:`resolve_date_to_check` -- which may be *anchored* to the
+    built will's frozen tx locktime so that an unchanged will never reads as
+    expired -- this helper resolves the threshold from the **stored settings
+    alone**.  Otherwise, when the stored relative locktime is shorter than the
+    frozen locktime of an old (still valid) built will (e.g. the delivery was
+    shortened from ``"2y"`` to ``"1y"``), the guard would compare the fresh
+    "1y" locktime against the old will's anchored threshold and wrongly fire,
+    even though locktime > threshold by the settings themselves.
+
+    * BASIC mode: no threshold exists.  Returns ``None`` and the caller falls
+      back to comparing the locktime against ``date_to_check`` (= now), so its
+      behaviour is unchanged.
+    * ADVANCED mode with an ABSOLUTE threshold: returns the stored threshold
+      as-is.
+    * ADVANCED mode with a RELATIVE threshold (``"30d"``/``"1y"``, meaning
+      "N days BEFORE the delivery"): the threshold is anchored to the locktime
+      resolved forward from *now* (the settings' own delivery reading, never a
+      built tx), keeping both sides of the comparison in the same reference
+      frame, as the settings widget displays it.
+
+    Returns ``None`` when there is no threshold to enforce (BASIC mode or a
+    missing stored value).
+    """
+    if is_basic_mode:
+        return None
+    threshold_raw = will_settings.get("threshold")
+    if threshold_raw is None:
+        return None
+    threshold = BalTimestamp(threshold_raw)
+    if threshold.unit is None:
+        return threshold.to_timestamp()
+    now_dt = (
+        datetime.fromtimestamp(now, tz=timezone.utc) if now is not None else None
+    )
+    locktime_dt = BalTimestamp(will_settings["locktime"]).to_date(now_dt)
+    return threshold.to_date(locktime_dt, reverse=True).timestamp()
+
+
 def check_alive_expired(
     is_basic_mode: bool, date_to_check: float, now: float | None = None
 ) -> bool:

bal/core/will.py

@@ -28,6 +28,7 @@ The status flags themselves (the source of truth) stay here; only the mapping
 
 from datetime import datetime, timezone
 
+from electrum.address_synchronizer import TX_HEIGHT_FUTURE, TX_HEIGHT_LOCAL
 from electrum.i18n import _
 from electrum.logging import Logger, get_logger
 from electrum.transaction import (
@@ -847,6 +848,48 @@ class Will:
         except Exception as e:
             _logger.error(f"save_valid_transactions_to_history failed: {e}")
 
+    @staticmethod
+    def remove_stale_wallet_history(wallet, history_label):
+        """Delete wallet-LOCAL will transactions saved under ``history_label``.
+
+        ``save_valid_transactions_to_history`` stores the not-yet-signed
+        inheritance txs into the wallet's local history; those local
+        placeholders nominally spend the coins they reference. When the will is
+        REBUILT (prepare/build, auto-rebuild, on-close rebuild, CLI build) the
+        stale placeholders must be removed so the coins become available again
+        to the new build (see ``Util.get_available_utxos``). Only
+        wallet-local/future (non-broadcast) txs whose label matches the history
+        label template are removed; confirmed/broadcast history is never
+        touched. Returns the txids that were removed.
+        """
+        if not wallet or not getattr(wallet, "adb", None):
+            return []
+        removed = []
+        for txid, label in Will._wallet_labels(wallet):
+            if not label or not Util._label_matches_history(label, history_label):
+                continue
+            try:
+                height = int(wallet.adb.get_tx_height(txid).height())
+            except Exception:
+                continue
+            if height not in (TX_HEIGHT_LOCAL, TX_HEIGHT_FUTURE):
+                continue
+            try:
+                wallet.adb.remove_transaction(txid)
+                removed.append(txid)
+            except Exception as e:
+                _logger.error(f"remove from history failed for {txid}: {e}")
+                continue
+            try:
+                wallet.set_label(txid, None)
+            except Exception as e:
+                _logger.error(f"set_label failed for {txid}: {e}")
+        try:
+            wallet.save_db()
+        except Exception as e:
+            _logger.error(f"save_db failed after history purge: {e}")
+        return removed
+
     @staticmethod
     def _add_transaction_to_history(wallet, tx, txid):
         """Store *tx* into the wallet's local history via ``adb``.
@@ -1213,9 +1256,9 @@ class Will:
 
             if Util.parse_locktime_string(heirs[h][2]) >= check_date:
                 count_heirs += 1
-                if h not in heirs_found:
-                    _logger.debug(f"heir: {h} not found")
-                    raise HeirNotFoundException(h)
+            if h not in heirs_found:
+                _logger.debug(f"heir: {h} not found")
+                raise HeirNotFoundException(h)
         if not count_heirs:
             raise NoHeirsException("there are not valid heirs")
         if self_willexecutor and no_willexecutor == 0: