fix(hashline): restore v3.11.2 legacy hash computation for backward compatibility

🤖 Generated with [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-openagent)

src/tools/hashline-edit/hash-computation.test.ts

@@ -72,6 +72,19 @@ describe("computeLineHash", () => {
     expect(hash1).toBe(hash2)
   })
 
+  it("preserves legacy hashes for internal whitespace variants", () => {
+    //#given
+    const content1 = "if (a && b) {"
+    const content2 = "if(a&&b){"
+
+    //#when
+    const hash1 = computeLegacyLineHash(1, content1)
+    const hash2 = computeLegacyLineHash(1, content2)
+
+    //#then
+    expect(hash1).toBe(hash2)
+  })
+
   it("ignores trailing whitespace differences", () => {
     //#given
     const content1 = "function hello() {"

src/tools/hashline-edit/hash-computation.ts

@@ -16,7 +16,7 @@ export function computeLineHash(lineNumber: number, content: string): string {
 }
 
 export function computeLegacyLineHash(lineNumber: number, content: string): string {
-  return computeNormalizedLineHash(lineNumber, content.replace(/\r/g, "").trim())
+  return computeNormalizedLineHash(lineNumber, content.replace(/\r/g, "").replace(/\s+/g, ""))
 }
 
 export function formatHashLine(lineNumber: number, content: string): string {

src/tools/hashline-edit/validation.test.ts

@@ -125,6 +125,15 @@ describe("validateLineRef", () => {
     expect(() => validateLineRef(lines, `1#${legacyHash}`)).not.toThrow()
   })
 
+  it("accepts legacy hashes for internal whitespace variants", () => {
+    //#given
+    const lines = ["if (a && b) {"]
+    const legacyHash = computeLegacyLineHash(1, "if(a&&b){")
+
+    //#when / #then
+    expect(() => validateLineRef(lines, `1#${legacyHash}`)).not.toThrow()
+  })
+
   it("shows >>> mismatch context in batched validation", () => {
     //#given
     const lines = ["one", "two", "three", "four"]