diff --git a/.github/workflows/fuzz.yml b/.github/workflows/fuzz-solana.yml
similarity index 88%
rename from .github/workflows/fuzz.yml
rename to .github/workflows/fuzz-solana.yml
index 5d9774bd..0e91baef 100644
--- a/.github/workflows/fuzz.yml
+++ b/.github/workflows/fuzz-solana.yml
@@ -1,9 +1,12 @@
-name: Fuzz Testing
+name: "Fuzz Testing: Solana"
 
 on:
   pull_request:
     types: [opened, synchronize, reopened, labeled]
 
+env:
+  NIGHTLY_VERSION: nightly-2026-03-13
+
 jobs:
   fuzz:
     if: contains(github.event.pull_request.labels.*.name, 'fuzz')
@@ -18,7 +21,7 @@ jobs:
       - name: Install Rust (nightly)
         uses: actions-rust-lang/setup-rust-toolchain@fb51252c7ba57d633bc668f941da052e410add48 # v1.13.0
         with:
-          toolchain: nightly-2026-03-13
+          toolchain: ${{ env.NIGHTLY_VERSION }}
       - name: Install cargo-fuzz
         run: cargo install cargo-fuzz --locked
       - name: Cache Rust dependencies
@@ -50,12 +53,12 @@ jobs:
       - name: Fuzz fuzz_transaction_string (30s)
         id: fuzz_transaction_string
         continue-on-error: true
-        run: cargo +nightly-2026-03-13 fuzz run fuzz_transaction_string -- -max_total_time=30
+        run: cargo +${{ env.NIGHTLY_VERSION }} fuzz run fuzz_transaction_string -- -max_total_time=30
         working-directory: src/chain_parsers/visualsign-solana/fuzz
       - name: Fuzz fuzz_versioned_transaction (30s)
         id: fuzz_versioned_transaction
         continue-on-error: true
-        run: cargo +nightly-2026-03-13 fuzz run fuzz_versioned_transaction -- -max_total_time=30
+        run: cargo +${{ env.NIGHTLY_VERSION }} fuzz run fuzz_versioned_transaction -- -max_total_time=30
         working-directory: src/chain_parsers/visualsign-solana/fuzz
       - name: Label PR on fuzz failure
         env:
diff --git a/.github/workflows/proptest.yml b/.github/workflows/proptest-solana.yml
similarity index 98%
rename from .github/workflows/proptest.yml
rename to .github/workflows/proptest-solana.yml
index 40123c18..5e57d54e 100644
--- a/.github/workflows/proptest.yml
+++ b/.github/workflows/proptest-solana.yml
@@ -1,4 +1,4 @@
-name: Property Tests
+name: "Property Tests: Solana"
 
 on:
   pull_request:
diff --git a/src/chain_parsers/visualsign-solana/tests/common/mod.rs b/src/chain_parsers/visualsign-solana/tests/common/mod.rs
index bacdf5e8..7503d8a2 100644
--- a/src/chain_parsers/visualsign-solana/tests/common/mod.rs
+++ b/src/chain_parsers/visualsign-solana/tests/common/mod.rs
@@ -143,3 +143,21 @@ pub fn find_text(fields: &[AnnotatedPayloadField], label: &str) -> Option<String
         None
     })
 }
+
+// ── IDL loading helpers ───────────────────────────────────────────────────────
+
+/// Load a real IDL from the path in the `IDL_FILE` environment variable.
+///
+/// Returns `None` when `IDL_FILE` is unset or the IDL fails validation,
+/// allowing `real_idl_*` tests to be silently skipped in CI.
+pub fn load_idl_from_env() -> Option<(String, solana_parser::solana::structs::Idl)> {
+    let path = std::env::var("IDL_FILE").ok()?;
+    let json = std::fs::read_to_string(&path).unwrap_or_else(|e| panic!("IDL_FILE={path}: {e}"));
+    match decode_idl_data(&json) {
+        Ok(idl) => Some((json, idl)),
+        Err(e) => {
+            eprintln!("IDL_FILE={path}: skipping — decode failed: {e}");
+            None
+        }
+    }
+}
diff --git a/src/chain_parsers/visualsign-solana/tests/fuzz_idl_parsing.rs b/src/chain_parsers/visualsign-solana/tests/fuzz_idl_parsing.rs
index d101ce72..55ae0a47 100644
--- a/src/chain_parsers/visualsign-solana/tests/fuzz_idl_parsing.rs
+++ b/src/chain_parsers/visualsign-solana/tests/fuzz_idl_parsing.rs
@@ -35,6 +35,8 @@ use solana_parser::{decode_idl_data, parse_instruction_with_idl};
 use solana_parser_fuzz_core::proptest as arb;
 use std::sync::Arc;
 
+mod common;
+
 // parse_instruction_with_idl ignores the program_id parameter (_program_id);
 // use an obviously fake value to avoid confusion with real known programs.
 const TEST_PROGRAM_ID: &str = "deadbeef1234deadbeef5678deadbeef";
@@ -849,19 +851,7 @@ fn size_guard_vec_u64_over_budget() {
 //
 // See scripts/fuzz_all_idls.sh to run against all embedded IDLs in one pass.
 
-fn load_idl_from_env() -> Option<(String, solana_parser::solana::structs::Idl)> {
-    let path = std::env::var("IDL_FILE").ok()?;
-    let json = std::fs::read_to_string(&path).unwrap_or_else(|e| panic!("IDL_FILE={path}: {e}"));
-    match decode_idl_data(&json) {
-        Ok(idl) => Some((json, idl)),
-        Err(e) => {
-            // IDL failed validation (e.g. duplicate type names, cyclic references).
-            // Skip these tests — they are not valid inputs for real_idl_* tests.
-            eprintln!("IDL_FILE={path}: skipping — decode failed: {e}");
-            None
-        }
-    }
-}
+use common::load_idl_from_env;
 
 /// Crash-safety test against a real IDL loaded from IDL_FILE.
 ///
diff --git a/src/chain_parsers/visualsign-solana/tests/real_idl_validation.rs b/src/chain_parsers/visualsign-solana/tests/real_idl_validation.rs
new file mode 100644
index 00000000..11caa613
--- /dev/null
+++ b/src/chain_parsers/visualsign-solana/tests/real_idl_validation.rs
@@ -0,0 +1,86 @@
+//! Structural invariant tests for real production IDLs.
+//!
+//! These tests assert properties of the decoded IDL structure itself —
+//! no random input generation, no proptest. They verify that `decode_idl_data`
+//! produces well-formed IDLs from production JSON files.
+//!
+//! Run: `IDL_FILE=/path/to/idl.json cargo test --test real_idl_validation`
+//! All IDLs: `scripts/fuzz_all_idls.sh`
+
+mod common;
+
+use common::load_idl_from_env;
+
+/// Every instruction in the decoded IDL must have a discriminator computed by
+/// decode_idl_data (either provided explicitly or derived via Anchor's SHA256
+/// scheme). A missing discriminator means the instruction is unreachable.
+#[test]
+fn real_idl_all_instructions_have_discriminators() {
+    let Some((_, idl)) = load_idl_from_env() else {
+        return;
+    };
+    for inst in &idl.instructions {
+        let disc = inst
+            .discriminator
+            .as_ref()
+            .unwrap_or_else(|| panic!("instruction '{}' has no discriminator", inst.name));
+        assert_eq!(
+            disc.len(),
+            8,
+            "instruction '{}' discriminator must be 8 bytes, got {}",
+            inst.name,
+            disc.len()
+        );
+    }
+}
+
+/// No two instructions in the IDL may share a discriminator — a collision would
+/// make them indistinguishable at parse time.
+#[test]
+fn real_idl_discriminators_are_unique() {
+    let Some((_, idl)) = load_idl_from_env() else {
+        return;
+    };
+    let mut seen: std::collections::HashMap<Vec<u8>, &str> = std::collections::HashMap::new();
+    for inst in &idl.instructions {
+        if let Some(disc) = &inst.discriminator {
+            if let Some(existing) = seen.get(disc) {
+                panic!(
+                    "discriminator collision between '{}' and '{}': {:?}",
+                    existing, inst.name, disc
+                );
+            }
+            seen.insert(disc.clone(), &inst.name);
+        }
+    }
+}
+
+/// No two instructions may share a name — duplicate names make dispatch results
+/// ambiguous and hint at an IDL construction error.
+#[test]
+fn real_idl_instruction_names_are_unique() {
+    let Some((_, idl)) = load_idl_from_env() else {
+        return;
+    };
+    let mut seen: std::collections::HashSet<&str> = std::collections::HashSet::new();
+    for inst in &idl.instructions {
+        assert!(
+            seen.insert(inst.name.as_str()),
+            "duplicate instruction name: '{}'",
+            inst.name
+        );
+    }
+}
+
+/// compute_idl_hash must be deterministic — the same JSON must produce the
+/// same hash on every call.
+#[test]
+fn real_idl_idl_hash_is_stable() {
+    let Some((json, _)) = load_idl_from_env() else {
+        return;
+    };
+    let h1 = solana_parser::compute_idl_hash(&json);
+    let h2 = solana_parser::compute_idl_hash(&json);
+    assert_eq!(h1, h2, "IDL hash must be deterministic");
+    assert!(!h1.is_empty(), "IDL hash must not be empty");
+}
diff --git a/src/rust-toolchain.toml b/src/rust-toolchain.toml
index bb2af9b2..dd5e6333 100644
--- a/src/rust-toolchain.toml
+++ b/src/rust-toolchain.toml
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "1.88"
+channel = "1.88.0"
 components = [ "rustfmt", "cargo", "clippy" ]
 profile = "minimal"