apollo_gateway: add compute_big_storage_key + cross-language fixture. (#14117)

Renames and relocates the GCS-naming helper per review feedback:

* The helper moves from `ProofFacts::big_storage_key` (in `starknet_api`)
  to a free function `compute_big_storage_key` alongside
  `GcsProofArchiveWriter` in `apollo_gateway::proof_archive_writer`. The
  storage-naming contract was coupling a public API type to the GCS
  layer; the new home keeps it next to the only producer of those keys.
* Renames `big_storage_key` → `compute_big_storage_key` since the
  function does Poseidon work — `compute_` signals derivation, not a
  property read.
* As a free function (not a trait method), the helper stays callable
  from any consumer side without requiring a `ProofArchiveWriter`
  instance + GCS config.

Also moves the JSON fixture under `apollo_gateway/resources/` and the
expect-test under `apollo_gateway/src/proof_archive_writer_test.rs`.
Drops the redundant `starts_with("proofs/")` rstest — the fixture pins
exact strings, of which the prefix is a strict subset.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: AvivYossef-starkware

Cargo.lock

@@ -54,6 +54,7 @@ tracing.workspace = true
 [dev-dependencies]
 apollo_class_manager_types = { workspace = true, features = ["testing"] }
 apollo_gateway_config = { workspace = true, features = ["testing"] }
+apollo_infra_utils.workspace = true
 apollo_mempool.workspace = true
 apollo_mempool_types = { workspace = true, features = ["testing"] }
 apollo_metrics = { workspace = true, features = ["testing"] }
@@ -67,6 +68,7 @@ blockifier = { workspace = true, features = ["mocks", "testing"] }
 blockifier_test_utils.workspace = true
 cairo-lang-sierra-to-casm.workspace = true
 criterion = { workspace = true, features = ["async_tokio"] }
+expect-test.workspace = true
 metrics.workspace = true
 metrics-exporter-prometheus.workspace = true
 mockall.workspace = true

crates/apollo_gateway/Cargo.toml

@@ -0,0 +1,29 @@
+[
+  {
+    "big_storage_key": "proofs/1330163329880897963929329415144033128916878238201091319571200413658610585730",
+    "proof_facts": [
+      "0x1",
+      "0x2",
+      "0x3"
+    ]
+  },
+  {
+    "big_storage_key": "proofs/2384960345383653703825803024708982182127528589318022519244349682493582074337",
+    "proof_facts": [
+      "0x0"
+    ]
+  },
+  {
+    "big_storage_key": "proofs/2423937516222001646661741181647152765517884388953635986164148712285196226589",
+    "proof_facts": [
+      "0x50524f4f4630",
+      "0x5649525455414c5f534e4f53",
+      "0x1",
+      "0x5649525455414c5f534e4f5330",
+      "0x7a0",
+      "0x2fa80",
+      "0x4d82f98134d9b03a412bd54c25aa1e92ca0261a745737ba52fd46dd25f537c0",
+      "0x0"
+    ]
+  }
+]

crates/apollo_gateway/resources/proof_facts_big_storage_keys.json

@@ -4,6 +4,8 @@ pub mod gateway;
 pub mod gateway_fixed_block_state_reader;
 pub mod metrics;
 pub mod proof_archive_writer;
+#[cfg(test)]
+mod proof_archive_writer_test;
 mod state_reader;
 #[cfg(any(feature = "testing", test))]
 mod state_reader_test_utils;

crates/apollo_gateway/src/lib.rs

@@ -12,6 +12,11 @@ use tokio::sync::OnceCell;
 // The expected error code for precondition failed errors when using `if_generation_match` in GCS.
 const GCS_ERROR_CODE_PRECONDITION_FAILED: u16 = 412;
 
+/// GCS object name where the Stwo proof for these facts is archived.
+pub fn compute_big_storage_key(proof_facts: &ProofFacts) -> String {
+    format!("proofs/{}", proof_facts.hash())
+}
+
 /// Trait for writing proof facts and proofs to large storage systems.
 /// Implementations should be thread-safe (Send + Sync).
 #[cfg_attr(any(feature = "testing", test), automock)]
@@ -65,9 +70,8 @@ impl ProofArchiveWriterTrait for GcsProofArchiveWriter {
         proof: Proof,
     ) -> Result<(), ProofArchiveError> {
         let client = self.client.get().expect("GCS client not connected. Call connect() first.");
-        let facts_hash = proof_facts.hash();
         let proof_bytes: Vec<u8> = proof.0.iter().flat_map(|&val| val.to_be_bytes()).collect();
-        let object_name = format!("proofs/{}", facts_hash);
+        let object_name = compute_big_storage_key(&proof_facts);
 
         let result = client
             .upload_object(

crates/apollo_gateway/src/proof_archive_writer.rs

@@ -0,0 +1,41 @@
+use std::path::PathBuf;
+use std::sync::LazyLock;
+
+use apollo_infra_utils::compile_time_cargo_manifest_dir;
+use expect_test::expect_file;
+use starknet_api::proof_facts;
+use starknet_api::transaction::fields::ProofFacts;
+use starknet_types_core::felt::Felt;
+
+use crate::proof_archive_writer::compute_big_storage_key;
+
+static PROOF_FACTS_BIG_STORAGE_KEYS_FIXTURE_PATH: LazyLock<PathBuf> = LazyLock::new(|| {
+    PathBuf::from(compile_time_cargo_manifest_dir!())
+        .join("resources/proof_facts_big_storage_keys.json")
+});
+
+/// Returns the cases pinned by the cross-language fixture.
+fn big_storage_key_cases() -> Vec<ProofFacts> {
+    vec![
+        proof_facts![Felt::from(1u64), Felt::from(2u64), Felt::from(3u64)],
+        proof_facts![Felt::ZERO],
+        ProofFacts::snos_proof_facts_for_testing(),
+    ]
+}
+
+/// Cross-language fixture for services that need to derive the proof archive key — regenerate with
+/// UPDATE_EXPECT=1.
+#[test]
+fn proof_facts_big_storage_keys_fixture() {
+    let fixture: Vec<serde_json::Value> = big_storage_key_cases()
+        .iter()
+        .map(|facts| {
+            serde_json::json!({
+                "proof_facts": facts.0.iter().map(|f| f.to_hex_string()).collect::<Vec<_>>(),
+                "big_storage_key": compute_big_storage_key(facts),
+            })
+        })
+        .collect();
+    let json = serde_json::to_string_pretty(&fixture).unwrap() + "\n";
+    expect_file![PROOF_FACTS_BIG_STORAGE_KEYS_FIXTURE_PATH.as_path()].assert_eq(&json);
+}