feat(stablecoin): add redemption rate update quote

modules/stablecoin/README.md

@@ -66,6 +66,23 @@ The result contains `accumulatedRateAtLastAccrual`, `lastAccruedAt`,
 string. Projection uses saturating timestamp subtraction and the on-chain
 seven-day compounding-window clamp. The method accepts no caller-provided time.
 
+### `redemptionRateUpdateQuote()`
+
+Reads Protocol Parameters, Redemption Price State, the configured market-price
+oracle, and canonical `CLOCK_01` account, then quotes the next controller tick
+without submitting a transaction. It projects the current redemption price
+with the stored rate before calling the same pure controller used on-chain.
+
+Ready quotes return `canSubmit: true`, `code: "ready"`, the current redemption
+and market prices, elapsed milliseconds, next redemption rate, next controller
+integral term, and integral/rate clamp bounds. All numeric values are exact
+decimal strings.
+
+A stale oracle, zero oracle price, or not-yet-due update returns a successful
+read-only quote with `canSubmit: false`, `code: "blocked"`, machine-readable
+`errors`, and explicit `null` next-controller values. Multiple blockers are
+reported in on-chain gate order. The frozen flag does not block this operation.
+
 ### `initializeProgram(request)`
 
 Required request fields:

modules/stablecoin/ffi/include/stablecoin_ffi.h

@@ -54,6 +54,14 @@ char *stablecoin_decode_redemption_price_state(const char *request_json);
  */
 char *stablecoin_current_global_state(const char *request_json);
 
+/**
+ * Quotes the next redemption-rate controller update without submitting it.
+ *
+ * # Safety
+ * `request_json` must be null or point to a live NUL-terminated byte string.
+ */
+char *stablecoin_redemption_rate_update_quote(const char *request_json);
+
 /**
  * Builds the exact wallet submission plan for `InitializeProgram`.
  *

modules/stablecoin/ffi/src/api/mod.rs

@@ -4,6 +4,7 @@ mod decode;
 mod plan;
 mod program;
 mod projection;
+mod quote;
 mod request;
 
 #[cfg(test)]
@@ -17,9 +18,11 @@ pub use decode::{
 pub use plan::initialize_program_plan;
 pub use program::program_info;
 pub use projection::current_global_state;
+pub use quote::redemption_rate_update_quote;
 pub use request::{
     CurrentGlobalStateRequest, DecodeProtocolParametersRequest, DecodeRedemptionPriceStateRequest,
     DecodeStabilityFeeAccumulatorRequest, InitializeProgramPlanRequest, ProgramInfoRequest,
+    RedemptionRateUpdateQuoteRequest,
 };
 use serde_json::Value;
 

modules/stablecoin/ffi/src/api/projection.rs

@@ -49,7 +49,7 @@ pub fn current_global_state(request: CurrentGlobalStateRequest) -> StablecoinRes
     }))
 }
 
-fn clock_timestamp(read: &crate::AccountRead) -> Result<u64, StablecoinApiError> {
+pub(super) fn clock_timestamp(read: &crate::AccountRead) -> Result<u64, StablecoinApiError> {
     let (account_id, account) =
         decode_account(read).map_err(|_| StablecoinApiError::new("account_read_failed"))?;
     if account_id != CLOCK_01_PROGRAM_ACCOUNT_ID {