fix: preserve case in watched contract matching

Stacks contract identifiers are case-sensitive — two contracts can share
the same name with different address casing. Case-insensitive normalization
was unsafe and could cause incorrect contract matches.

- Remove .toLowerCase() from normalizeWatchedContracts and contractMatches
- Whitespace trimming of STACKFLOW_CONTRACTS entries is preserved
- Update test to use correct-case identifier (with padding to exercise trim)
- Correct README to reflect case-sensitive matching

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: warmidris

README.md

@@ -258,7 +258,7 @@ STACKFLOW_NODE_FORWARDING_REVEAL_RETRY_MAX_ATTEMPTS=20
 
 If `STACKFLOW_CONTRACTS` is omitted, the stackflow-node automatically monitors any
 contract identifier matching `*.stackflow*`.
-When set, `STACKFLOW_CONTRACTS` entries are trimmed and matched case-insensitively.
+When set, `STACKFLOW_CONTRACTS` entries are trimmed of whitespace and matched case-sensitively (Stacks contract identifiers are case-sensitive).
 The current implementation uses Node's `node:sqlite` module for persistence.
 `STACKFLOW_NODE_SIGNATURE_VERIFIER_MODE` supports `readonly` (default),
 `accept-all`, and `reject-all`. Non-`readonly` modes are intended for testing.

server/src/observer-parser.ts

@@ -241,7 +241,7 @@ function collectContractEventCandidates(
 
 function normalizeWatchedContracts(watchedContracts: string[]): string[] {
   return watchedContracts
-    .map((contract) => contract.trim().toLowerCase())
+    .map((contract) => contract.trim())
     .filter((contract) => contract.length > 0);
 }
 
@@ -254,8 +254,7 @@ function contractMatches(
   }
 
   if (watchedContracts.length > 0) {
-    const normalizedContractId = contractId.toLowerCase();
-    return watchedContracts.some((candidate) => candidate === normalizedContractId);
+    return watchedContracts.some((candidate) => candidate === contractId);
   }
 
   return DEFAULT_STACKFLOW_CONTRACT_PATTERN.test(contractId);

tests/stackflow-node-observer.test.ts

@@ -228,7 +228,7 @@ describe('watchtower event parser', () => {
     };
 
     const events = extractStackflowPrintEvents(payload, {
-      watchedContracts: ['  st1pqhqkv0rjxzfy1dgx8mnsnyve3vgzjsrtpgzgm.custom-flow  '],
+      watchedContracts: [`  ${CLOSER}.custom-flow  `],
     });
 
     expect(events).toHaveLength(1);