diff --git a/packages/coding-agent/src/prompts/tools/read.md b/packages/coding-agent/src/prompts/tools/read.md
index 8712ff14a..92c8e0806 100644
--- a/packages/coding-agent/src/prompts/tools/read.md
+++ b/packages/coding-agent/src/prompts/tools/read.md
@@ -15,7 +15,7 @@ Read files, directories, archives, SQLite databases, images, documents, internal
 Append `:<sel>` to `path`. The bare path falls back to the default mode.
 
 - _(none)_ — parseable code → structural summary (signatures kept, bodies elided); other files → read from the start (up to {{DEFAULT_LIMIT}} lines).
-- `:50` — read from line 50 onward.
+- `:50` / `:50-` — read from line 50 onward.
 - `:50-200` — lines 50–200 inclusive.
 - `:50+150` — 150 lines starting at line 50.
 - `:20+1` — exactly one line.
diff --git a/packages/coding-agent/src/tools/path-utils.ts b/packages/coding-agent/src/tools/path-utils.ts
index dad41bb69..be280eab5 100644
--- a/packages/coding-agent/src/tools/path-utils.ts
+++ b/packages/coding-agent/src/tools/path-utils.ts
@@ -7,8 +7,8 @@ import { InternalUrlRouter } from "../internal-urls";
 import { ToolError } from "./tool-errors";
 
 const UNICODE_SPACES = /[\u00A0\u2000-\u200A\u202F\u205F\u3000]/g;
-const FILE_LINE_RANGE_RE = /^(?:L?\d+(?:[-+]L?\d+)?(?:,L?\d+(?:[-+]L?\d+)?)*|raw|conflicts)$/i;
-const FILE_LINE_RANGE_ONLY_RE = /^L?\d+(?:[-+]L?\d+)?(?:,L?\d+(?:[-+]L?\d+)?)*$/i;
+const FILE_LINE_RANGE_RE = /^(?:L?\d+(?:[-+]L?\d+|-)?(?:,L?\d+(?:[-+]L?\d+|-)?)*|raw|conflicts)$/i;
+const FILE_LINE_RANGE_ONLY_RE = /^L?\d+(?:[-+]L?\d+|-)?(?:,L?\d+(?:[-+]L?\d+|-)?)*$/i;
 const FILE_RAW_ONLY_RE = /^raw$/i;
 const NARROW_NO_BREAK_SPACE = "\u202F";
 const TOP_LEVEL_INTERNAL_URL_PREFIXES = [
diff --git a/packages/coding-agent/src/tools/read.ts b/packages/coding-agent/src/tools/read.ts
index 15a081c39..00a127cd1 100644
--- a/packages/coding-agent/src/tools/read.ts
+++ b/packages/coding-agent/src/tools/read.ts
@@ -513,7 +513,7 @@ type ParsedSelector =
 	| { kind: "conflicts" }
 	| { kind: "lines"; ranges: [LineRange, ...LineRange[]]; raw?: boolean };
 
-const LINE_RANGE_RE = /^L?(\d+)(?:([-+])L?(\d+))?$/i;
+const LINE_RANGE_RE = /^L?(\d+)(?:([-+])L?(\d+)?)?$/i;
 
 /** Returns true when the selector requested verbatim/raw output (alone or combined with a range). */
 function isRawSelector(parsed: ParsedSelector): boolean {
@@ -541,10 +541,13 @@ function parseLineRangeChunk(sel: string): LineRange | null {
 		}
 		rawEnd = rawStart + rhs - 1;
 	} else if (sep === "-") {
-		if (rhs === undefined || rhs < rawStart) {
-			throw new ToolError(`Invalid range ${rawStart}-${rhs ?? 0}: end must be >= start.`);
+		// `301-` is shorthand for "from 301 onward" — equivalent to bare `301`.
+		if (rhs !== undefined) {
+			if (rhs < rawStart) {
+				throw new ToolError(`Invalid range ${rawStart}-${rhs}: end must be >= start.`);
+			}
+			rawEnd = rhs;
 		}
-		rawEnd = rhs;
 	}
 	return { startLine: rawStart, endLine: rawEnd };
 }