diff --git a/CHANGELOG.md b/CHANGELOG.md
index 35e2c0a..353c6fb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 All notable changes to the Sharpy smart contract are documented here.
 
 ## [Unreleased]
+- feat(contract): `get_tranche_remaining_bps(id)` view + cumulative-bps invariant (`released + remaining == 10000`) — feat/tranche-remaining (closes #193)
 - feat(contract): `resolve_route_chain(id, max_depth)` bounded follower + `get_route_chain_len(id)` cycle-safe depth view — feat/route-chain-depth (closes #192)
 - feat(contract): `get_stream_state(id)` + `preview_vested(id)` pure views; `withdraw_vested` repeat-withdraw idempotency fix (`total - vested`), cancel edge docs — feat/stream-vest-preview (closes #191)
 - feat(events): invoice_updated (`inv_upd`) now emitted on `set_discount` and all whitelist mutations (`set/add/remove`), after the field-specific event; `is_invoice_expired(id)` read-only helper mirrors the `refund`/`refund_batch` expiry trigger — feat/event-taxonomy (closes #183)
diff --git a/contracts/sharpy/src/lib.rs b/contracts/sharpy/src/lib.rs
index 51464fb..76cf63d 100644
--- a/contracts/sharpy/src/lib.rs
+++ b/contracts/sharpy/src/lib.rs
@@ -1436,7 +1436,16 @@ impl SharpyContract {
         cumulative
     }
 
+    /// Remaining releasable basis points (`10000 - released_bps`); 10000 when untouched.
+    /// Pure view: `released + remaining == 10000` always. Poll before submitting
+    /// `release_tranche` to avoid over-release panics.
+    pub fn get_tranche_remaining_bps(env: Env, invoice_id: u64) -> u32 {
+        let released: u32 = env.storage().persistent().get::<(Symbol,u64), TrancheState>(&tranche_key(invoice_id)).map(|s| s.released_bps).unwrap_or(0);
+        10_000u32.checked_sub(released).expect("tranche: underflow in remaining")
+    }
+
     /// Cumulative released basis points for `invoice_id` (0 when untouched).
+    /// Invariant: `get_released_bps + get_tranche_remaining_bps == 10000`.
     pub fn get_released_bps(env: Env, invoice_id: u64) -> u32 {
         env.storage().persistent().get::<(Symbol,u64), TrancheState>(&tranche_key(invoice_id)).map(|s| s.released_bps).unwrap_or(0)
     }
diff --git a/contracts/sharpy/src/test.rs b/contracts/sharpy/src/test.rs
index 5818657..faae5c2 100644
--- a/contracts/sharpy/src/test.rs
+++ b/contracts/sharpy/src/test.rs
@@ -5492,3 +5492,132 @@ mod test_route_chain_c {
         assert_eq!(client.resolve_route_chain(&a, &5u32), c);
     }
 }
+
+#[cfg(test)]
+mod test_tranche_invariant_a {
+    use soroban_sdk::{testutils::Address as _, Address, Env, Vec};
+    use crate::SharpyContractClient;
+    fn setup() -> (Env, SharpyContractClient<'static>) {
+        let env = Env::default();
+        env.mock_all_auths();
+        let cid = env.register(crate::SharpyContract, ());
+        let c = SharpyContractClient::new(&env, &cid);
+        let a = Address::generate(&env);
+        let t = Address::generate(&env);
+        c.initialize(&a, &t);
+        (env, c)
+    }
+    fn mk(env: &Env, client: &SharpyContractClient<'_>, creator: &Address) -> u64 {
+        let r = Address::generate(env);
+        let tok = Address::generate(env);
+        let dl = env.ledger().timestamp() + 86400;
+        let opts = crate::types::InvoiceOptions { escrow_enabled: false, escrow_release_delay: None, split_rules: Vec::new(env), auto_resolve_rules: Vec::new(env), arbitrator: None };
+        client.create_invoice(creator, &Vec::from_array(env, [r]), &Vec::from_array(env, [100i128]), &Vec::from_array(env, [tok]), &dl, &opts)
+    }
+    #[test]
+    fn test_remaining_starts_full() {
+        let (env, client) = setup();
+        let creator = Address::generate(&env);
+        let id = mk(&env, &client, &creator);
+        assert_eq!(client.get_released_bps(&id), 0u32);
+        assert_eq!(client.get_tranche_remaining_bps(&id), 10_000u32);
+    }
+    #[test]
+    fn test_partial_sums_to_full() {
+        let (env, client) = setup();
+        let creator = Address::generate(&env);
+        let id = mk(&env, &client, &creator);
+        assert_eq!(client.release_tranche(&creator, &id, &3000u32), 3000u32);
+        assert_eq!(client.get_tranche_remaining_bps(&id), 7000u32);
+        assert_eq!(client.release_tranche(&creator, &id, &7000u32), 10_000u32);
+        assert_eq!(client.get_tranche_remaining_bps(&id), 0u32);
+    }
+}
+
+#[cfg(test)]
+mod test_tranche_invariant_b {
+    use soroban_sdk::{testutils::Address as _, Address, Env, Vec};
+    use crate::SharpyContractClient;
+    fn setup() -> (Env, SharpyContractClient<'static>) {
+        let env = Env::default();
+        env.mock_all_auths();
+        let cid = env.register(crate::SharpyContract, ());
+        let c = SharpyContractClient::new(&env, &cid);
+        let a = Address::generate(&env);
+        let t = Address::generate(&env);
+        c.initialize(&a, &t);
+        (env, c)
+    }
+    fn mk(env: &Env, client: &SharpyContractClient<'_>, creator: &Address) -> u64 {
+        let r = Address::generate(env);
+        let tok = Address::generate(env);
+        let dl = env.ledger().timestamp() + 86400;
+        let opts = crate::types::InvoiceOptions { escrow_enabled: false, escrow_release_delay: None, split_rules: Vec::new(env), auto_resolve_rules: Vec::new(env), arbitrator: None };
+        client.create_invoice(creator, &Vec::from_array(env, [r]), &Vec::from_array(env, [100i128]), &Vec::from_array(env, [tok]), &dl, &opts)
+    }
+    #[test]
+    #[should_panic(expected = "tranches exceed 100%")]
+    fn test_over_release_panics() {
+        let (env, client) = setup();
+        let creator = Address::generate(&env);
+        let id = mk(&env, &client, &creator);
+        client.release_tranche(&creator, &id, &6000u32);
+        client.release_tranche(&creator, &id, &5000u32);
+    }
+    #[test]
+    fn test_small_steps_accumulate_exactly() {
+        let (env, client) = setup();
+        let creator = Address::generate(&env);
+        let id = mk(&env, &client, &creator);
+        let mut cum = 0u32;
+        for _ in 0..10 {
+            cum = client.release_tranche(&creator, &id, &1000u32);
+        }
+        assert_eq!(cum, 10_000u32);
+        assert_eq!(client.get_released_bps(&id) + client.get_tranche_remaining_bps(&id), 10_000u32);
+    }
+}
+
+#[cfg(test)]
+mod test_tranche_invariant_c {
+    use soroban_sdk::{testutils::Address as _, Address, Env, Vec};
+    use crate::SharpyContractClient;
+    fn setup() -> (Env, SharpyContractClient<'static>) {
+        let env = Env::default();
+        env.mock_all_auths();
+        let cid = env.register(crate::SharpyContract, ());
+        let c = SharpyContractClient::new(&env, &cid);
+        let a = Address::generate(&env);
+        let t = Address::generate(&env);
+        c.initialize(&a, &t);
+        (env, c)
+    }
+    fn mk(env: &Env, client: &SharpyContractClient<'_>, creator: &Address) -> u64 {
+        let r = Address::generate(env);
+        let tok = Address::generate(env);
+        let dl = env.ledger().timestamp() + 86400;
+        let opts = crate::types::InvoiceOptions { escrow_enabled: false, escrow_release_delay: None, split_rules: Vec::new(env), auto_resolve_rules: Vec::new(env), arbitrator: None };
+        client.create_invoice(creator, &Vec::from_array(env, [r]), &Vec::from_array(env, [100i128]), &Vec::from_array(env, [tok]), &dl, &opts)
+    }
+    #[test]
+    fn test_tranche_isolated_per_invoice() {
+        let (env, client) = setup();
+        let creator = Address::generate(&env);
+        let a = mk(&env, &client, &creator);
+        let b = mk(&env, &client, &creator);
+        client.release_tranche(&creator, &a, &2500u32);
+        assert_eq!(client.get_released_bps(&a), 2500u32);
+        assert_eq!(client.get_tranche_remaining_bps(&a), 7500u32);
+        assert_eq!(client.get_released_bps(&b), 0u32);
+        assert_eq!(client.get_tranche_remaining_bps(&b), 10_000u32);
+    }
+    #[test]
+    #[should_panic(expected = "only creator can release tranches")]
+    fn test_non_creator_tranche_panics() {
+        let (env, client) = setup();
+        let creator = Address::generate(&env);
+        let other = Address::generate(&env);
+        let id = mk(&env, &client, &creator);
+        client.release_tranche(&other, &id, &100u32);
+    }
+}