From 6c0857b39d83bc5de2ef48cdabc4482bbaa2531a Mon Sep 17 00:00:00 2001
From: Loris Leiva <loris.leiva@gmail.com>
Date: Sat, 29 Aug 2026 11:17:15 +0100
Subject: [PATCH] Fix variable string and bytes PDA seeds in legacy Anchor IDLs

This PR is a follow-up to #1126, which fixed byte-array PDA seeds for Anchor v01 IDLs. The legacy v00 path has the same bug: `pdaNodeFromAnchorV00` strips the Borsh size prefix from constant `string` and `bytes` seeds but not from variable ones, so a variable seed derives a different PDA than the on-chain program. This change hoists the seed type conversion into a single helper used by both branches, so constant and variable seeds are now consistent by construction.
---
 .changeset/long-stamps-bow.md                 |  5 +++++
 packages/nodes-from-anchor/src/v00/PdaNode.ts | 20 +++++++++++--------
 .../test/v00/PdaNode.test.ts                  | 20 +++++++++++++++++++
 3 files changed, 37 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/long-stamps-bow.md

diff --git a/.changeset/long-stamps-bow.md b/.changeset/long-stamps-bow.md
new file mode 100644
index 000000000..fb2f758c5
--- /dev/null
+++ b/.changeset/long-stamps-bow.md
@@ -0,0 +1,5 @@
+---
+'@codama/nodes-from-anchor': patch
+---
+
+Fix variable `string` and `bytes` PDA seeds from legacy Anchor IDLs to derive from their raw bytes instead of their Borsh size-prefixed encoding, matching the existing behaviour of constant seeds.
diff --git a/packages/nodes-from-anchor/src/v00/PdaNode.ts b/packages/nodes-from-anchor/src/v00/PdaNode.ts
index cec5be7f3..03a05bd61 100644
--- a/packages/nodes-from-anchor/src/v00/PdaNode.ts
+++ b/packages/nodes-from-anchor/src/v00/PdaNode.ts
@@ -10,32 +10,28 @@ import {
     PdaSeedNode,
     stringTypeNode,
     stringValueNode,
+    TypeNode,
     variablePdaSeedNode,
 } from '@codama/nodes';
 
-import { IdlV00PdaDef } from './idl';
+import { IdlV00PdaDef, IdlV00Type } from './idl';
 import { typeNodeFromAnchorV00 } from './typeNodes';
 
 export function pdaNodeFromAnchorV00(idl: IdlV00PdaDef): PdaNode {
     const name = camelCase(idl.name ?? '');
     const seeds = (idl.seeds ?? []).map((seed): PdaSeedNode => {
         if (seed.kind === 'constant') {
-            const type = (() => {
-                if (seed.type === 'string') return stringTypeNode('utf8');
-                if (seed.type === 'bytes') return bytesTypeNode();
-                return typeNodeFromAnchorV00(seed.type);
-            })();
             const value = (() => {
                 if (typeof seed.value === 'string') return stringValueNode(seed.value);
                 if (typeof seed.value === 'number') return numberValueNode(seed.value);
                 return booleanValueNode(seed.value);
             })();
-            return constantPdaSeedNode(type, value);
+            return constantPdaSeedNode(pdaSeedTypeNodeFromAnchorV00(seed.type), value);
         }
         if (seed.kind === 'variable') {
             return variablePdaSeedNode(
                 seed.name,
-                typeNodeFromAnchorV00(seed.type),
+                pdaSeedTypeNodeFromAnchorV00(seed.type),
                 seed.description ? [seed.description] : [],
             );
         }
@@ -43,3 +39,11 @@ export function pdaNodeFromAnchorV00(idl: IdlV00PdaDef): PdaNode {
     });
     return pdaNode({ name, seeds });
 }
+
+function pdaSeedTypeNodeFromAnchorV00(type: IdlV00Type): TypeNode {
+    // Anchor derives PDA seeds from raw bytes, so strings and byte
+    // arrays lose their Borsh size prefix when used as seeds.
+    if (type === 'string') return stringTypeNode('utf8');
+    if (type === 'bytes') return bytesTypeNode();
+    return typeNodeFromAnchorV00(type);
+}
diff --git a/packages/nodes-from-anchor/test/v00/PdaNode.test.ts b/packages/nodes-from-anchor/test/v00/PdaNode.test.ts
index d3c6b48a5..be85a409c 100644
--- a/packages/nodes-from-anchor/test/v00/PdaNode.test.ts
+++ b/packages/nodes-from-anchor/test/v00/PdaNode.test.ts
@@ -1,9 +1,11 @@
 import {
+    bytesTypeNode,
     constantPdaSeedNode,
     constantPdaSeedNodeFromProgramId,
     numberTypeNode,
     numberValueNode,
     pdaNode,
+    stringTypeNode,
     variablePdaSeedNode,
 } from '@codama/nodes';
 import { expect, test } from 'vitest';
@@ -31,3 +33,21 @@ test('it creates PDA nodes', () => {
         }),
     );
 });
+
+test('it removes the string prefix from variable seeds', () => {
+    const node = pdaNodeFromAnchorV00({
+        name: 'myPda',
+        seeds: [{ description: '', kind: 'variable', name: 'label', type: 'string' }],
+    });
+
+    expect(node).toEqual(pdaNode({ name: 'myPda', seeds: [variablePdaSeedNode('label', stringTypeNode('utf8'))] }));
+});
+
+test('it removes the bytes prefix from variable seeds', () => {
+    const node = pdaNodeFromAnchorV00({
+        name: 'myPda',
+        seeds: [{ description: '', kind: 'variable', name: 'seedData', type: 'bytes' }],
+    });
+
+    expect(node).toEqual(pdaNode({ name: 'myPda', seeds: [variablePdaSeedNode('seedData', bytesTypeNode())] }));
+});