diff --git a/packages/coding-agent/src/prompts/tools/read.md b/packages/coding-agent/src/prompts/tools/read.md
index 2bc641189..1cc01b0ba 100644
--- a/packages/coding-agent/src/prompts/tools/read.md
+++ b/packages/coding-agent/src/prompts/tools/read.md
@@ -25,7 +25,7 @@ Read files, directories, archives, SQLite, images, documents, internal resources
 
 - Directory → depth-limited dirent listing.
 {{#if IS_HL_MODE}}
-- File + selector → snapshot tag header + numbered lines: `[src/foo.ts#1A2B]` then `41:def alpha():`. Copy `[PATH#TAG]` for anchored edits; ops use bare line numbers. NEVER fabricate the tag.
+- File + selector → filename-only snapshot header + numbered lines: `[foo.ts#1A2B]` then `41:def alpha():`. Copy `[FILENAME#TAG]` for anchored edits; ops use bare line numbers. NEVER fabricate the tag.
 {{else}}
 {{#if IS_LINE_NUMBER_MODE}}
 - File + selector → numbered lines: `41|def alpha():`.
diff --git a/packages/coding-agent/src/tools/read.ts b/packages/coding-agent/src/tools/read.ts
index 2dd814528..0b26e37b7 100644
--- a/packages/coding-agent/src/tools/read.ts
+++ b/packages/coding-agent/src/tools/read.ts
@@ -170,6 +170,10 @@ interface HashlineHeaderContext {
 	fullText?: string;
 }
 
+function formatReadHashlineHeader(displayPath: string, tag: string): string {
+	return formatHashlineHeader(path.basename(displayPath), tag);
+}
+
 function recordFullHashlineContext(
 	session: ToolSession,
 	absolutePath: string | undefined,
@@ -180,7 +184,7 @@ function recordFullHashlineContext(
 	const normalized = normalizeToLF(fullText);
 	const tag = getFileSnapshotStore(session).record(canonicalSnapshotKey(absolutePath), normalized);
 	return {
-		header: formatHashlineHeader(displayPath, tag),
+		header: formatReadHashlineHeader(displayPath, tag),
 		tag,
 		fullText: normalized,
 	};
@@ -203,7 +207,7 @@ async function readHashlineHeaderContext(
 }
 
 function hashlineHeaderContext(displayPath: string, tag: string): HashlineHeaderContext {
-	return { header: formatHashlineHeader(displayPath, tag), tag };
+	return { header: formatReadHashlineHeader(displayPath, tag), tag };
 }
 
 function prependHashlineHeader(text: string, context: HashlineHeaderContext | undefined): string {
@@ -1598,7 +1602,7 @@ export class ReadTool implements AgentTool<typeof readSchema, ReadToolDetails> {
 			const tag = await recordFileSnapshot(this.session, absolutePath);
 			if (tag) {
 				recordSeenLinesFromBody(this.session, absolutePath, tag, outputText);
-				outputText = `${formatHashlineHeader(formatPathRelativeToCwd(absolutePath, this.session.cwd), tag)}\n${outputText}`;
+				outputText = `${formatReadHashlineHeader(formatPathRelativeToCwd(absolutePath, this.session.cwd), tag)}\n${outputText}`;
 			}
 		}
 		if (notices.length > 0) {
diff --git a/packages/coding-agent/test/read-multi-range.test.ts b/packages/coding-agent/test/read-multi-range.test.ts
index 975fe0ce2..99c30f4aa 100644
--- a/packages/coding-agent/test/read-multi-range.test.ts
+++ b/packages/coding-agent/test/read-multi-range.test.ts
@@ -48,13 +48,29 @@ describe("read tool multi-range selector", () => {
 		await fs.rm(tmpDir, { recursive: true, force: true });
 	});
 
+	it("uses only the filename in hashline headers for nested files", async () => {
+		const filePath = path.join(tmpDir, "src", "nested", "numbered.txt");
+		await fs.mkdir(path.dirname(filePath), { recursive: true });
+		await fs.writeFile(filePath, "alpha\nbeta\n");
+
+		const tool = new ReadTool(createSession(tmpDir));
+		const text = textOutput(await tool.execute("call-filename-header", { path: filePath }));
+		const firstLine = text.split("\n")[0];
+
+		expect(firstLine).toMatch(/^\[numbered\.txt#[0-9A-F]{4}\]$/);
+		expect(firstLine).not.toContain("src");
+	});
+
 	it("returns both ranges separated by an elision marker", async () => {
-		const filePath = path.join(tmpDir, "numbered.txt");
+		const filePath = path.join(tmpDir, "src", "numbered.txt");
+		await fs.mkdir(path.dirname(filePath), { recursive: true });
 		await fs.writeFile(filePath, makeNumberedContent(50));
 
 		const tool = new ReadTool(createSession(tmpDir));
 		const result = await tool.execute("call-multi", { path: `${filePath}:3-5,20-22` });
 		const text = textOutput(result);
+		const firstLine = text.split("\n")[0];
+		expect(firstLine).toMatch(/^\[numbered\.txt#[0-9A-F]{4}\]$/);
 
 		expect(text).toContain("line 3");
 		expect(text).toContain("line 4");
diff --git a/packages/coding-agent/test/read-summary.test.ts b/packages/coding-agent/test/read-summary.test.ts
index 0539b3fd9..e21f12897 100644
--- a/packages/coding-agent/test/read-summary.test.ts
+++ b/packages/coding-agent/test/read-summary.test.ts
@@ -62,7 +62,8 @@ describe("read summary", () => {
 	});
 
 	it("summarizes parseable TypeScript files without an explicit selector", async () => {
-		const fixture = path.join(tmpDir, "fixture.ts");
+		const fixture = path.join(tmpDir, "src", "fixture.ts");
+		await fs.mkdir(path.dirname(fixture), { recursive: true });
 		await fs.writeFile(
 			fixture,
 			"export function alpha(value: string): string {\n\tconst clean = value.trim();\n\tconst label = clean || 'alpha';\n\treturn label.toUpperCase();\n}\n\nexport function beta(): number {\n\tconst one = 1;\n\tconst two = 2;\n\treturn one + two;\n}\n",
@@ -71,6 +72,8 @@ describe("read summary", () => {
 		const tool = new ReadTool(createSession(tmpDir));
 		const result = await tool.execute("read-summary-ts", { path: fixture });
 		const text = textOutput(result);
+		const firstLine = text.split("\n")[0];
+		expect(firstLine).toMatch(/^\[fixture\.ts#[0-9A-F]{4}\]$/);
 
 		expect(text).toContain("export function alpha(value: string): string { … }");
 		expect(text).toContain("export function beta(): number { … }");