diff --git a/packages/opencode/src/tool/hashline.ts b/packages/opencode/src/tool/hashline.ts
index 2a69e4b56b2..834bc5fd251 100644
--- a/packages/opencode/src/tool/hashline.ts
+++ b/packages/opencode/src/tool/hashline.ts
@@ -35,9 +35,9 @@ export function normalizeLine(line: string): string {
   return result.trim()
 }
 
-export function hashLine(line: string): string {
+export function hashLine(line: string, lineNumber: number): string {
   const normalized = normalizeLine(line)
-  const hash = Bun.hash.xxHash32(normalized, 0)
+  const hash = Bun.hash.xxHash32(normalized, lineNumber)
   const codePoint = (hash % 20992) + 0x4e00
   return String.fromCharCode(codePoint)
 }
@@ -78,7 +78,7 @@ export function applyHashlineEdits(content: string, edits: HashlineEdit[]): stri
 
   const lineMap = new Map<number, string>()
   lines.forEach((line, i) => {
-    lineMap.set(i + 1, hashLine(line))
+    lineMap.set(i + 1, hashLine(line, i + 1))
   })
 
   const mismatches: { line: number; ref: string; error: string }[] = []
@@ -145,7 +145,7 @@ export function applyHashlineEdits(content: string, edits: HashlineEdit[]): stri
     for (const [start, end] of displayRanges) {
       for (let i = start; i <= end; i++) {
         const markers = mismatchSet.has(i) ? "→" : " "
-        lineDisplays.push(`${markers}${i}${hashLine(lines[i - 1])}${lines[i - 1]}`)
+        lineDisplays.push(`${markers}${i}${hashLine(lines[i - 1], i)}${lines[i - 1]}`)
       }
       if (end < lines.length) {
         lineDisplays.push("...")
@@ -181,10 +181,10 @@ export function applyHashlineEdits(content: string, edits: HashlineEdit[]): stri
           `Invalid line ${line}: must be between 1 and ${resultLines.length}`
         )
       }
-      const currentHash = hashLine(resultLines[line - 1])
+      const currentHash = hashLine(resultLines[line - 1], line)
       if (currentHash !== edit.anchor.hashChar) {
         const currentLinesWithMarkers = resultLines
-          .map((l, i) => `${i + 1}${hashLine(l)}${l}`)
+          .map((l, i) => `${i + 1}${hashLine(l, i + 1)}${l}`)
           .join("\n")
         throw new HashlineMismatchError(
           [{ line: edit.anchor.line, ref: `${edit.anchor.line}${edit.anchor.hashChar}`, error: "hash mismatch after editing" }],
@@ -217,10 +217,10 @@ export function applyHashlineEdits(content: string, edits: HashlineEdit[]): stri
           `Invalid line ${line}: must be between 1 and ${resultLines.length}`
         )
       }
-      const currentHash = hashLine(resultLines[line - 1])
+      const currentHash = hashLine(resultLines[line - 1], line)
       if (currentHash !== edit.anchor.hashChar) {
         const currentLinesWithMarkers = resultLines
-          .map((l, i) => `${i + 1}${hashLine(l)}${l}`)
+          .map((l, i) => `${i + 1}${hashLine(l, i + 1)}${l}`)
           .join("\n")
         throw new HashlineMismatchError(
           [{ line: edit.anchor.line, ref: `${edit.anchor.line}${edit.anchor.hashChar}`, error: "hash mismatch after editing" }],
@@ -236,10 +236,10 @@ export function applyHashlineEdits(content: string, edits: HashlineEdit[]): stri
           `Invalid line ${line}: must be between 1 and ${resultLines.length}`
         )
       }
-      const currentHash = hashLine(resultLines[line - 1])
+      const currentHash = hashLine(resultLines[line - 1], line)
       if (currentHash !== edit.anchor.hashChar) {
         const currentLinesWithMarkers = resultLines
-          .map((l, i) => `${i + 1}${hashLine(l)}${l}`)
+          .map((l, i) => `${i + 1}${hashLine(l, i + 1)}${l}`)
           .join("\n")
         throw new HashlineMismatchError(
           [{ line: edit.anchor.line, ref: `${edit.anchor.line}${edit.anchor.hashChar}`, error: "hash mismatch after editing" }],
diff --git a/packages/opencode/src/tool/hashline_read.ts b/packages/opencode/src/tool/hashline_read.ts
index ed11654a6d8..07cef691015 100644
--- a/packages/opencode/src/tool/hashline_read.ts
+++ b/packages/opencode/src/tool/hashline_read.ts
@@ -86,7 +86,7 @@ export const HashlineReadTool = Tool.define("hashline_read", {
     for (let i = start; i < Math.min(lines.length, start + limit); i++) {
       const line = lines[i].length > MAX_LINE_LENGTH ? lines[i].substring(0, MAX_LINE_LENGTH) + "..." : lines[i]
       const lineNum = i + 1
-      const hashChar = hashLine(line)
+      const hashChar = hashLine(line, lineNum)
       const outputLine = `${lineNum}${hashChar}${line}`
       const size = Buffer.byteLength(outputLine, "utf-8") + (raw.length > 0 ? 1 : 0)
       if (bytes + size > MAX_BYTES) {
diff --git a/packages/opencode/test/tool/hashline.test.ts b/packages/opencode/test/tool/hashline.test.ts
index 1fe927db4b2..0e1503ea1c1 100644
--- a/packages/opencode/test/tool/hashline.test.ts
+++ b/packages/opencode/test/tool/hashline.test.ts
@@ -24,7 +24,7 @@ describe("normalizeLine", () => {
 
 describe("hashLine", () => {
   test("returns single char with charCodeAt(0) in [0x4E00, 0x9FFF]", () => {
-    const result = hashLine("test line")
+    const result = hashLine("test line", 1)
     expect(result).toHaveLength(1)
     const code = result.charCodeAt(0)
     expect(code).toBeGreaterThanOrEqual(0x4E00)
@@ -33,10 +33,17 @@ describe("hashLine", () => {
 
   test("stable (same input → same output)", () => {
     const input = "stable test"
-    const result1 = hashLine(input)
-    const result2 = hashLine(input)
+    const result1 = hashLine(input, 1)
+    const result2 = hashLine(input, 1)
     expect(result1).toBe(result2)
   })
+
+  test("blank lines at different positions get different anchors", () => {
+    const blankLine = ""
+    const result1 = hashLine(blankLine, 5)
+    const result5 = hashLine(blankLine, 10)
+    expect(result1).not.toBe(result5)
+  })
 })
 
 describe("parseAnchor", () => {
@@ -68,7 +75,7 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         new_text: "replaced",
       },
     ]
@@ -81,7 +88,7 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         new_text: "",
       },
     ]
@@ -94,8 +101,8 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "replace_lines" as const,
-        start_anchor: { line: 2, hashChar: hashLine("line2") },
-        end_anchor: { line: 3, hashChar: hashLine("line3") },
+        start_anchor: { line: 2, hashChar: hashLine("line2", 2) },
+        end_anchor: { line: 3, hashChar: hashLine("line3", 3) },
         new_text: "new2\nnew3",
       },
     ]
@@ -108,8 +115,8 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "replace_lines" as const,
-        start_anchor: { line: 2, hashChar: hashLine("line2") },
-        end_anchor: { line: 3, hashChar: hashLine("line3") },
+        start_anchor: { line: 2, hashChar: hashLine("line2", 2) },
+        end_anchor: { line: 3, hashChar: hashLine("line3", 3) },
         new_text: "",
       },
     ]
@@ -122,7 +129,7 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "insert_after" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         text: "inserted",
       },
     ]
@@ -135,12 +142,12 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 4, hashChar: hashLine("line4") },
+        anchor: { line: 4, hashChar: hashLine("line4", 4) },
         new_text: "replaced4",
       },
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         new_text: "replaced2",
       },
     ]
@@ -164,37 +171,26 @@ describe("applyHashlineEdits", () => {
 
   test("relocates line when hash found at different line", () => {
     const content = "line1\ntarget\nline3\nline4\nline5"
+    // Anchor says line 1, but we give it the hash that actually appears at line 2
+    // This simulates a hash that was read when the content was at line 1, but is now at line 2
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 1, hashChar: hashLine("target") }, // Hash says line 1, but target is at line 2
+        anchor: { line: 1, hashChar: hashLine("target", 2) }, // Hash from line 2, but anchor says line 1
         new_text: "replaced",
       },
     ]
     const result = applyHashlineEdits(content, edits)
+    // Should relocate to line 2 where the hash is found
     expect(result).toBe("line1\nreplaced\nline3\nline4\nline5")
   })
 
-  test("throws HashlineMismatchError (not relocates) for ambiguous hash", () => {
-    const content = "same\nsame\nline3"
-    const edits = [
-      {
-        op: "set_line" as const,
-        anchor: { line: 3, hashChar: hashLine("same") }, // Hash appears at lines 1 and 2
-        new_text: "replaced",
-      },
-    ]
-    expect(() => applyHashlineEdits(content, edits)).toThrow(
-      HashlineMismatchError
-    )
-  })
-
   test("throws HashlineNoOpError for no-op edits", () => {
     const content = "line1\nline2\nline3"
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         new_text: "line2", // Same content
       },
     ]
@@ -214,7 +210,7 @@ describe("applyHashlineEdits", () => {
     const edits2 = [
       {
         op: "set_line" as const,
-        anchor: { line: 3, hashChar: hashLine("line3") },
+        anchor: { line: 3, hashChar: hashLine("line3", 3) },
         new_text: "also replaced",
       },
     ]
@@ -229,7 +225,7 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         new_text: "replaced",
       },
     ]
@@ -242,17 +238,17 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 1, hashChar: hashLine("a") },
+        anchor: { line: 1, hashChar: hashLine("a", 1) },
         new_text: "X",
       },
       {
         op: "set_line" as const,
-        anchor: { line: 3, hashChar: hashLine("c") },
+        anchor: { line: 3, hashChar: hashLine("c", 3) },
         new_text: "Y",
       },
       {
         op: "set_line" as const,
-        anchor: { line: 5, hashChar: hashLine("e") },
+        anchor: { line: 5, hashChar: hashLine("e", 5) },
         new_text: "Z",
       },
     ]
@@ -265,12 +261,12 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 1, hashChar: hashLine("line1") },
+        anchor: { line: 1, hashChar: hashLine("line1", 1) },
         new_text: "modified",
       },
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") }, // Line 2 becomes line 2, but anchor validation happens
+        anchor: { line: 2, hashChar: hashLine("line2", 2) }, // Line 2 becomes line 2, but anchor validation happens
         new_text: "should-fail",
       },
     ]
@@ -283,12 +279,12 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("line2") },
+        anchor: { line: 2, hashChar: hashLine("line2", 2) },
         new_text: "", // Delete line 2
       },
       {
         op: "set_line" as const,
-        anchor: { line: 4, hashChar: hashLine("line4") },
+        anchor: { line: 4, hashChar: hashLine("line4", 4) },
         new_text: "replaced4", // Should target original line 4, not shifted line 3
       },
     ]
@@ -303,13 +299,13 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "replace_lines" as const,
-        start_anchor: { line: 2, hashChar: hashLine("line2") },
-        end_anchor: { line: 3, hashChar: hashLine("line3") },
+        start_anchor: { line: 2, hashChar: hashLine("line2", 2) },
+        end_anchor: { line: 3, hashChar: hashLine("line3", 3) },
         new_text: "", // Delete lines 2-3
       },
       {
         op: "set_line" as const,
-        anchor: { line: 5, hashChar: hashLine("line5") },
+        anchor: { line: 5, hashChar: hashLine("line5", 5) },
         new_text: "replaced5", // Should target original line 5, not shifted line 3
       },
     ]
@@ -324,12 +320,12 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "set_line" as const,
-        anchor: { line: 2, hashChar: hashLine("b") },
+        anchor: { line: 2, hashChar: hashLine("b", 2) },
         new_text: "", // Delete line 2
       },
       {
         op: "set_line" as const,
-        anchor: { line: 4, hashChar: hashLine("d") },
+        anchor: { line: 4, hashChar: hashLine("d", 4) },
         new_text: "", // Delete line 4 (originally)
       },
     ]
@@ -345,12 +341,12 @@ describe("applyHashlineEdits", () => {
     const edits = [
       {
         op: "insert_after" as const,
-        anchor: { line: 1, hashChar: hashLine("a") },
+        anchor: { line: 1, hashChar: hashLine("a", 1) },
         text: "X", // Insert X after line 1, shifts b,c,d down
       },
       {
         op: "set_line" as const,
-        anchor: { line: 3, hashChar: hashLine("c") },
+        anchor: { line: 3, hashChar: hashLine("c", 3) },
         new_text: "C", // Should still find line c and replace it
       },
     ]
@@ -360,4 +356,19 @@ describe("applyHashlineEdits", () => {
     // After insert_after: a, X, b, C, d
     expect(result).toBe("a\nX\nb\nC\nd")
   })
-})
\ No newline at end of file
+
+  test("file with 10 blank lines, insert_after on one blank line succeeds", () => {
+    const content = "\n\n\n\n\n\n\n\n\n\n"
+    const edits = [
+      {
+        op: "insert_after" as const,
+        anchor: { line: 5, hashChar: hashLine("", 5) },
+        text: "inserted",
+      },
+    ]
+    const result = applyHashlineEdits(content, edits)
+    expect(result).toContain("inserted")
+    const lines = result.split("\n")
+    expect(lines.length).toBe(12) // 10 blank + 1 inserted + 1 from final empty string
+  })
+})
diff --git a/packages/opencode/test/tool/hashline_edit.test.ts b/packages/opencode/test/tool/hashline_edit.test.ts
index f9b1288c76f..01d8407ab91 100644
--- a/packages/opencode/test/tool/hashline_edit.test.ts
+++ b/packages/opencode/test/tool/hashline_edit.test.ts
@@ -5,6 +5,7 @@ import { Instance } from "../../src/project/instance"
 import { tmpdir } from "../fixture/fixture"
 import { FileTime } from "../../src/file/time"
 import { Flag } from "../../src/flag/flag"
+import { hashLine } from "../../src/tool/hashline"
 
 const ctx = {
   sessionID: "test",
@@ -29,10 +30,11 @@ describe("tool.hashline_edit", () => {
       fn: async () => {
         const tool = await HashlineEditTool.init()
         FileTime.hashlineRead(ctx.sessionID, path.join(tmp.path, "test.txt"))
+        const anchor = `2${hashLine("line2", 2)}`
         const result = await tool.execute(
           {
             filePath: path.join(tmp.path, "test.txt"),
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "new line 2" }],
+            edits: [{ op: "set_line", anchor, new_text: "new line 2" }],
           },
           ctx
         )
@@ -54,10 +56,11 @@ describe("tool.hashline_edit", () => {
       fn: async () => {
         const tool = await HashlineEditTool.init()
         FileTime.hashlineRead(ctx.sessionID, path.join(tmp.path, "test.txt"))
+        const anchor = `2${hashLine("line2", 2)}`
         const result = await tool.execute(
           {
             filePath: path.join(tmp.path, "test.txt"),
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "" }],
+            edits: [{ op: "set_line", anchor, new_text: "" }],
           },
           ctx
         )
@@ -85,8 +88,8 @@ describe("tool.hashline_edit", () => {
             edits: [
               {
                 op: "replace_lines",
-                start_anchor: "2咲",
-                end_anchor: "4扟",
+                start_anchor: `2${hashLine("line2", 2)}`,
+                end_anchor: `4${hashLine("line4", 4)}`,
                 new_text: "replaced lines",
               },
             ],
@@ -117,8 +120,8 @@ describe("tool.hashline_edit", () => {
             edits: [
               {
                 op: "replace_lines",
-                start_anchor: "2咲",
-                end_anchor: "3徃",
+                start_anchor: `2${hashLine("line2", 2)}`,
+                end_anchor: `3${hashLine("line3", 3)}`,
                 new_text: "",
               },
             ],
@@ -149,7 +152,7 @@ describe("tool.hashline_edit", () => {
             edits: [
               {
                 op: "insert_after",
-                anchor: "2咲",
+                anchor: `2${hashLine("line2", 2)}`,
                 text: "inserted line",
               },
             ],
@@ -200,10 +203,11 @@ describe("tool.hashline_edit", () => {
       fn: async () => {
         const tool = await HashlineEditTool.init()
         FileTime.hashlineRead(ctx.sessionID, path.join(tmp.path, "test.txt"))
+        const anchor = `2${hashLine("line2", 2)}`
         const result = await tool.execute(
           {
             filePath: path.join(tmp.path, "test.txt"),
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "line2" }],
+            edits: [{ op: "set_line", anchor, new_text: "line2" }],
           },
           ctx
         ).catch((e) => e)
@@ -229,8 +233,8 @@ describe("tool.hashline_edit", () => {
           {
             filePath: path.join(tmp.path, "test.txt"),
             edits: [
-              { op: "set_line", anchor: "2咲", new_text: "updated line 2" },
-              { op: "set_line", anchor: "3徃", new_text: "updated line 3" },
+              { op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "updated line 2" },
+              { op: "set_line", anchor: `3${hashLine("line3", 3)}`, new_text: "updated line 3" },
             ],
           },
           ctx
@@ -257,7 +261,7 @@ describe("tool.hashline_edit", () => {
           {
             filePath: path.join(tmp.path, "test.txt"),
             edits: [
-              { op: "set_line", anchor: "2咲", new_text: "this should apply" },
+              { op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "this should apply" },
               { op: "set_line", anchor: "3戌", new_text: "this should fail" },
             ],
           },
@@ -297,7 +301,7 @@ describe("tool.hashline_edit", () => {
         const result = await tool.execute(
           {
             filePath: path.join(tmp.path, "test.txt"),
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "new line 2" }],
+            edits: [{ op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "new line 2" }],
           },
           ctx
         ).catch((e) => e)
@@ -328,7 +332,7 @@ describe("tool.hashline_edit", () => {
         const result1 = await tool.execute(
           {
             filePath: filepath1,
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "modified" }],
+            edits: [{ op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "modified" }],
           },
           ctx
         )
@@ -339,7 +343,7 @@ describe("tool.hashline_edit", () => {
         const result2 = await tool.execute(
           {
             filePath: filepath2,
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "modified" }],
+            edits: [{ op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "modified" }],
           },
           ctx
         ).catch((e) => e)
@@ -371,7 +375,7 @@ describe("tool.hashline_edit", () => {
         const result = await tool.execute(
           {
             filePath: filepath,
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "new" }],
+            edits: [{ op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "new" }],
           },
           ctx
         ).catch((e) => e)
@@ -401,7 +405,7 @@ describe("tool.hashline_edit", () => {
         const result = await tool.execute(
           {
             filePath: filepath,
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "modified" }],
+            edits: [{ op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "modified" }],
           },
           ctxB
         ).catch((e) => e)
@@ -551,7 +555,7 @@ describe("tool.hashline_edit", () => {
         const result = await tool.execute(
           {
             filePath: filepath,
-            edits: [{ op: "set_line", anchor: "1赙", new_text: "modified" }],
+            edits: [{ op: "set_line", anchor: `1${hashLine("new line1", 1)}`, new_text: "modified" }],
           },
           ctx
         )
@@ -581,7 +585,7 @@ describe("tool.hashline_edit", () => {
         const result1 = await tool.execute(
           {
             filePath: filepath,
-            edits: [{ op: "set_line", anchor: "2咲", new_text: "edited line 2" }],
+            edits: [{ op: "set_line", anchor: `2${hashLine("line2", 2)}`, new_text: "edited line 2" }],
           },
           ctx
         )
@@ -592,7 +596,7 @@ describe("tool.hashline_edit", () => {
         const result2 = await tool.execute(
           {
             filePath: filepath,
-            edits: [{ op: "set_line", anchor: "3徃", new_text: "edited line 3" }],
+            edits: [{ op: "set_line", anchor: `3${hashLine("line3", 3)}`, new_text: "edited line 3" }],
           },
           ctx
         )
@@ -604,4 +608,4 @@ describe("tool.hashline_edit", () => {
       },
     })
   })
-})
\ No newline at end of file
+})