fix(tokens/hackathon): store name_seed on Hackathon to satisfy IDL builder

Anchor's IDL builder does not support function calls inside seeds = [...]
constraints (anchor-syn rejects super::name_seed(&hackathon.name)). Store
the SHA-256 hash on the Hackathon account so every other instruction can
reference hackathon.name_seed directly. create_hackathon now takes the
seed as an extra instruction arg (also an allowed seed expression) and
the handler enforces name_seed == sha256(name) to keep the binding.

Author: mikemaccana-edwardbot

tokens/hackathon/anchor/programs/hackathon/src/error.rs

@@ -20,4 +20,6 @@ pub enum HackathonError {
     PrizeCounterOverflow,
     #[msg("Cannot close hackathon: at least one prize is still active")]
     PrizesStillActive,
+    #[msg("name_seed argument does not match sha256(name)")]
+    NameSeedMismatch,
 }

tokens/hackathon/anchor/programs/hackathon/src/instructions/add_prize.rs

@@ -20,7 +20,7 @@ pub struct AddPrize<'info> {
     #[account(
         mut,
         has_one = authority,
-        seeds = [b"hackathon", authority.key().as_ref(), super::name_seed(&hackathon.name).as_ref()],
+        seeds = [b"hackathon", authority.key().as_ref(), hackathon.name_seed.as_ref()],
         bump = hackathon.bump,
     )]
     pub hackathon: Account<'info, Hackathon>,

tokens/hackathon/anchor/programs/hackathon/src/instructions/cancel_prize.rs

@@ -27,7 +27,7 @@ pub struct CancelPrize<'info> {
 
     #[account(
         has_one = authority,
-        seeds = [b"hackathon", authority.key().as_ref(), super::name_seed(&hackathon.name).as_ref()],
+        seeds = [b"hackathon", authority.key().as_ref(), hackathon.name_seed.as_ref()],
         bump = hackathon.bump,
     )]
     pub hackathon: Account<'info, Hackathon>,

tokens/hackathon/anchor/programs/hackathon/src/instructions/close_hackathon.rs

@@ -19,7 +19,7 @@ pub struct CloseHackathon<'info> {
         mut,
         has_one = authority,
         close = rent_destination,
-        seeds = [b"hackathon", authority.key().as_ref(), super::name_seed(&hackathon.name).as_ref()],
+        seeds = [b"hackathon", authority.key().as_ref(), hackathon.name_seed.as_ref()],
         bump = hackathon.bump,
     )]
     pub hackathon: Account<'info, Hackathon>,

tokens/hackathon/anchor/programs/hackathon/src/instructions/create_hackathon.rs

@@ -6,7 +6,7 @@ use crate::state::{Hackathon, HACKATHON_NAME_MAX_LEN};
 use super::name_seed;
 
 #[derive(Accounts)]
-#[instruction(name: String)]
+#[instruction(name: String, name_seed_arg: [u8; 32])]
 pub struct CreateHackathon<'info> {
     // Pays rent for the Hackathon account. Separate from `authority` so a
     // Squads vault PDA (which cannot pay rent directly) can still be the
@@ -21,27 +21,44 @@ pub struct CreateHackathon<'info> {
     /// CHECK: stored verbatim as `hackathon.authority`; no onchain reads.
     pub authority: UncheckedAccount<'info>,
 
+    // The PDA is seeded by `name_seed_arg` (an instruction argument) rather
+    // than computing `sha256(name)` inside the seed expression — Anchor's
+    // IDL builder does not support function calls in seed expressions. The
+    // handler then verifies the binding (`name_seed_arg == sha256(name)`)
+    // before storing both on the account.
     #[account(
         init,
         payer = payer,
         space = Hackathon::DISCRIMINATOR.len() + Hackathon::INIT_SPACE,
-        seeds = [b"hackathon", authority.key().as_ref(), name_seed(&name).as_ref()],
+        seeds = [b"hackathon", authority.key().as_ref(), name_seed_arg.as_ref()],
         bump
     )]
     pub hackathon: Account<'info, Hackathon>,
 
     pub system_program: Program<'info, System>,
 }
 
-pub fn handle_create_hackathon(context: Context<CreateHackathon>, name: String) -> Result<()> {
+pub fn handle_create_hackathon(
+    context: Context<CreateHackathon>,
+    name: String,
+    name_seed_arg: [u8; 32],
+) -> Result<()> {
     require!(!name.is_empty(), HackathonError::EmptyName);
     require!(
         name.len() <= HACKATHON_NAME_MAX_LEN,
         HackathonError::NameTooLong
     );
+    // Bind `name_seed_arg` to `name` so the seed cannot be chosen
+    // independently of the stored name. Without this, a caller could create
+    // a hackathon at any PDA address and claim any human-readable name.
+    require!(
+        name_seed_arg == name_seed(&name),
+        HackathonError::NameSeedMismatch
+    );
 
     context.accounts.hackathon.set_inner(Hackathon {
         authority: context.accounts.authority.key(),
+        name_seed: name_seed_arg,
         prize_count: 0,
         bump: context.bumps.hackathon,
         name,

tokens/hackathon/anchor/programs/hackathon/src/instructions/pay_winner.rs

@@ -16,7 +16,7 @@ pub struct PayWinner<'info> {
     pub caller: Signer<'info>,
 
     #[account(
-        seeds = [b"hackathon", hackathon.authority.as_ref(), super::name_seed(&hackathon.name).as_ref()],
+        seeds = [b"hackathon", hackathon.authority.as_ref(), hackathon.name_seed.as_ref()],
         bump = hackathon.bump,
     )]
     pub hackathon: Account<'info, Hackathon>,

tokens/hackathon/anchor/programs/hackathon/src/instructions/set_winner.rs

@@ -11,7 +11,7 @@ pub struct SetWinner<'info> {
 
     #[account(
         has_one = authority,
-        seeds = [b"hackathon", authority.key().as_ref(), super::name_seed(&hackathon.name).as_ref()],
+        seeds = [b"hackathon", authority.key().as_ref(), hackathon.name_seed.as_ref()],
         bump = hackathon.bump,
     )]
     pub hackathon: Account<'info, Hackathon>,

tokens/hackathon/anchor/programs/hackathon/src/lib.rs

@@ -28,8 +28,16 @@ pub mod hackathon {
     // Create a hackathon controlled by `authority` (in practice a Squads vault
     // PDA). The hackathon's name is hashed into the PDA seeds so the same
     // authority can run multiple hackathons.
-    pub fn create_hackathon(context: Context<CreateHackathon>, name: String) -> Result<()> {
-        instructions::create_hackathon::handle_create_hackathon(context, name)
+    //
+    // `name_seed` must equal `sha256(name)` — passed as a separate argument
+    // because Anchor's IDL builder does not support function calls inside
+    // `seeds = [...]` constraints. The handler enforces the binding.
+    pub fn create_hackathon(
+        context: Context<CreateHackathon>,
+        name: String,
+        name_seed: [u8; 32],
+    ) -> Result<()> {
+        instructions::create_hackathon::handle_create_hackathon(context, name, name_seed)
     }
 
     // Register a new prize under an existing hackathon. The mint and target

tokens/hackathon/anchor/programs/hackathon/src/state/hackathon.rs

@@ -12,12 +12,18 @@ pub struct Hackathon {
     // program treats it as an opaque pubkey: privileged handlers check
     // `signer == authority` and nothing more.
     pub authority: Pubkey,
+    // SHA-256 of `name`, stored on the account so other instructions can
+    // reference it directly in their `seeds = [...]` constraints without
+    // calling a function on `name` (Anchor's IDL builder does not support
+    // function calls in seed expressions). Bound to `name` by the
+    // `create_hackathon` handler.
+    pub name_seed: [u8; 32],
     // Monotonic counter used to seed Prize PDAs. u8 caps at 255 prizes per
     // hackathon, which is plenty for the target use case (30-100 prizes).
     pub prize_count: u8,
     pub bump: u8,
-    // Free-form human-readable name. Hashed into the Hackathon PDA seeds so a
-    // single authority can run multiple hackathons.
+    // Free-form human-readable name. Bound into the Hackathon PDA via
+    // `name_seed` so a single authority can run multiple hackathons.
     #[max_len(HACKATHON_NAME_MAX_LEN)]
     pub name: String,
 }

tokens/hackathon/anchor/programs/hackathon/tests/common/world.rs

@@ -369,6 +369,7 @@ pub fn create_hackathon_instruction(
     hackathon: &Pubkey,
     name: String,
 ) -> Instruction {
+    let name_seed = hackathon_name_seed(&name);
     Instruction {
         program_id: hackathon::id(),
         accounts: hackathon::accounts::CreateHackathon {
@@ -378,7 +379,7 @@ pub fn create_hackathon_instruction(
             system_program: anchor_lang::solana_program::system_program::ID,
         }
         .to_account_metas(None),
-        data: hackathon::instruction::CreateHackathon { name }.data(),
+        data: hackathon::instruction::CreateHackathon { name, name_seed }.data(),
     }
 }
 
@@ -529,7 +530,7 @@ pub fn prize_vault_address(prize: &Pubkey, mint: &Pubkey) -> Pubkey {
 
 // Local mirror of the program's `name_seed` so tests can derive the PDA
 // without depending on the program's private `instructions::shared` module.
-fn hackathon_name_seed(name: &str) -> [u8; 32] {
+pub fn hackathon_name_seed(name: &str) -> [u8; 32] {
     use sha2::{Digest, Sha256};
     let mut hasher = Sha256::new();
     hasher.update(name.as_bytes());