fix(dao): audit punch list — H-1 to H-4 + M-2 + pallas bump

Lands the high-priority fixes from the 2026-05-06 audit before any
mainnet submit of the new vote/cosign/advance/destroy txs.

## H-1: Locked→Finished gate (MCP tool)

`dao_proposal_advance_unsigned` now refuses LockedToFinished unless
`tx_lower_ms > executing_end`. During the executing period the
validator demands gstMoved=true (governor input present); builder
doesn't include the governor input, so a tx in that window would
fee-burn. The proper Locked→Finished + GAT-mint flow is Phase 4c-bis;
this gate keeps us out of the broken middle.

## H-2 + H-4: strict-boundary + tx-upper-inside-period (MCP tool)

Validator's pgetRelation is strict on PAfter (`period_end < lb`)
and demands `ub <= period_end` on PWithin. Tool now picks PWithin
only when `tx_lower_ms >= period_start && tx_upper_ms <= period_end`,
PAfter only when `tx_lower_ms > period_end` strictly, and explicit-
errors on the boundary-straddling case (when tx validity range
crosses out of the target period). Same logic mirrored for the
VotingReady→Locked + VotingReady→Finished branches.

## H-3: vote builder lower-bound preflight (MCP tool)

`dao_proposal_vote_unsigned` previously checked only validity_upper
vs voting_end_ms. Validator demands BOTH `voting_start <= lb` AND
`ub <= voting_end`. Vote-too-early would hit "too early or invalid"
script error. New preflight on tx_lower_ms vs voting_start.

## M-2: DRep deposit pulled from ProtocolParams

Hardcoded constant (500 ADA) was wrong if the protocol changes
drep_deposit OR if the DRep was originally registered at a different
deposit amount (deregistration must match registration). Added
`drep_deposit_lovelace: u64` to ProtocolParams (default 500 ADA),
governance.rs build_signed_drep_registration / deregistration now
read from params instead of the constant. Constant kept for
backward compat with a doc note pointing at the params field.

## Pallas fork bump 507fd9da → 8091abd1

M-4 from the audit landed on the fork: voting_procedures builder
debug_assert_ne!s against empty CBOR map (0xa0) and docs the
upstream NonEmptyKeyValuePairs::decode footgun.

L-1 from the audit was a false finding — the audit subagent
misread the constants. PROPOSAL_CREATE_*_EX_UNITS are already at
the post-2026-05-05-H-2 values (5M mem / 2G steps per spend, 2M / 1G
per mint). The new builders alias these correctly. No change needed.

crates/aldabra-core/src/governance.rs

@@ -36,8 +36,11 @@ use crate::tx::InputUtxo;
 use crate::{Network, PaymentKey, ProtocolParams, StakeKey, WalletError};
 
 /// Conway DRep registration deposit. Mainnet protocol parameter
-/// `drep_deposit` is currently 500 ADA. Caller can pass an override
-/// via `params` if a hardfork changes it; default constant here.
+/// `drep_deposit` is currently 500 ADA. **Use `params.drep_deposit_lovelace`
+/// instead of this constant** — it's kept here for backward-compat callers
+/// only. AUDIT-2026-05-06 M-2: hardcoding the deposit means a protocol
+/// change (or an old DRep registered at a different deposit) will silently
+/// fail ledger validation. Always pull from current chain params.
 pub const DREP_REGISTRATION_DEPOSIT_LOVELACE: u64 = 500_000_000;
 
 /// Two witnesses (payment + stake) — same overhead as
@@ -263,7 +266,7 @@ pub fn build_signed_drep_registration(
         }
     };
 
-    let cert = Certificate::RegDRepCert(drep_credential, DREP_REGISTRATION_DEPOSIT_LOVELACE, anchor);
+    let cert = Certificate::RegDRepCert(drep_credential, params.drep_deposit_lovelace, anchor);
     let cert_bytes = minicbor::to_vec(&cert)
         .map_err(|e| WalletError::Derivation(format!("encode RegDRep cert: {e}")))?;
 
@@ -274,7 +277,7 @@ pub fn build_signed_drep_registration(
         available_utxos,
         change_address_bech32,
         vec![cert_bytes],
-        DREP_REGISTRATION_DEPOSIT_LOVELACE,
+        params.drep_deposit_lovelace,
         params,
     )
 }
@@ -483,16 +486,15 @@ pub fn build_signed_drep_deregistration(
 ) -> Result<Vec<u8>, WalletError> {
     let stake_pkh = stake_key.public_key_hash();
     let drep_credential = StakeCredential::AddrKeyhash(stake_pkh);
-    let cert = Certificate::UnRegDRepCert(drep_credential, DREP_REGISTRATION_DEPOSIT_LOVELACE);
+    let cert = Certificate::UnRegDRepCert(drep_credential, params.drep_deposit_lovelace);
     let cert_bytes = minicbor::to_vec(&cert)
         .map_err(|e| WalletError::Derivation(format!("encode UnRegDRep cert: {e}")))?;
 
-    // Negative deposit — we get it back. Two-pass fee accounts for it
-    // by leaving `deposit` at 0 here and letting the wallet output absorb
-    // the refund. Note: pallas-txbuilder writes the deposit as a negative
-    // contribution implicitly via the cert; the change calc here just
-    // needs to know we DON'T owe the protocol anything. Caller should
-    // expect their wallet output to grow by 500 ADA - fee.
+    // Refund equals the deposit originally paid. Critical: this MUST match
+    // what the DRep was originally registered with, not "current chain
+    // drep_deposit." If the protocol changed deposit between registration
+    // and deregistration, caller needs to override `params.drep_deposit_lovelace`
+    // to the original-registration value. Otherwise ledger silently fails.
     sign_cert_tx_with_refund(
         payment_key,
         stake_key,
@@ -500,7 +502,7 @@ pub fn build_signed_drep_deregistration(
         available_utxos,
         change_address_bech32,
         vec![cert_bytes],
-        DREP_REGISTRATION_DEPOSIT_LOVELACE,
+        params.drep_deposit_lovelace,
         params,
     )
 }

crates/aldabra-core/src/tx.rs

@@ -79,6 +79,11 @@ pub struct ProtocolParams {
     /// `None`, Plutus paths skip script_data_hash and the chain will
     /// reject with `PPViewHashesDontMatch`.
     pub plutus_v3_cost_model: Option<Vec<i64>>,
+    /// Conway DRep registration deposit (ledger param `drep_deposit`).
+    /// Mainnet default: 500 ADA. Used by `governance::build_signed_drep_*`.
+    /// Pass the chain's current value when constructing — registering
+    /// with the wrong amount fails ledger validation silently.
+    pub drep_deposit_lovelace: u64,
 }
 
 impl Default for ProtocolParams {
@@ -95,6 +100,7 @@ impl Default for ProtocolParams {
             // or fetched from `epoch_params`. None by default keeps
             // the ada-only / mint paths zero-cost.
             plutus_v3_cost_model: None,
+            drep_deposit_lovelace: 500_000_000,
         }
     }
 }