refactor(arg-parsing): extract shared parseSlashSeparatedArg helper

The slash-splitting logic was duplicated across event/view.ts, trace/view.ts,
and log/view.ts. Centralise it in src/lib/arg-parsing.ts so future bug fixes
only need to be made in one place.

Author: BYK

src/commands/event/view.ts

@@ -9,6 +9,7 @@ import { getEvent } from "../../lib/api-client.js";
 import {
   ProjectSpecificationType,
   parseOrgProjectArg,
+  parseSlashSeparatedArg,
   spansFlag,
 } from "../../lib/arg-parsing.js";
 import { openInBrowser } from "../../lib/browser.js";
@@ -113,30 +114,11 @@ export function parsePositionalArgs(args: string[]): {
   }
 
   if (args.length === 1) {
-    const slashIdx = first.indexOf("/");
-
-    if (slashIdx === -1) {
-      // No slashes — plain event ID
-      return { eventId: first, targetArg: undefined };
-    }
-
-    // Event IDs are hex and never contain "/" — this must be a structured
-    // "org/project/eventId" or "org/project" (missing event ID)
-    const lastSlashIdx = first.lastIndexOf("/");
-
-    if (slashIdx === lastSlashIdx) {
-      // Exactly one slash: "org/project" without event ID
-      throw new ContextError("Event ID", USAGE_HINT);
-    }
-
-    // Two+ slashes: split on last "/" → target + eventId
-    const targetArg = first.slice(0, lastSlashIdx);
-    const eventId = first.slice(lastSlashIdx + 1);
-
-    if (!eventId) {
-      throw new ContextError("Event ID", USAGE_HINT);
-    }
-
+    const { id: eventId, targetArg } = parseSlashSeparatedArg(
+      first,
+      "Event ID",
+      USAGE_HINT
+    );
     return { eventId, targetArg };
   }
 

src/commands/log/view.ts

@@ -7,7 +7,10 @@
 import { buildCommand } from "@stricli/core";
 import type { SentryContext } from "../../context.js";
 import { getLog } from "../../lib/api-client.js";
-import { parseOrgProjectArg } from "../../lib/arg-parsing.js";
+import {
+  parseOrgProjectArg,
+  parseSlashSeparatedArg,
+} from "../../lib/arg-parsing.js";
 import { openInBrowser } from "../../lib/browser.js";
 import { ContextError, ValidationError } from "../../lib/errors.js";
 import { formatLogDetails, writeJson } from "../../lib/formatters/index.js";
@@ -48,30 +51,11 @@ export function parsePositionalArgs(args: string[]): {
   }
 
   if (args.length === 1) {
-    const slashIdx = first.indexOf("/");
-
-    if (slashIdx === -1) {
-      // No slashes — plain log ID
-      return { logId: first, targetArg: undefined };
-    }
-
-    // Log IDs are hex and never contain "/" — this must be a structured
-    // "org/project/logId" or "org/project" (missing log ID)
-    const lastSlashIdx = first.lastIndexOf("/");
-
-    if (slashIdx === lastSlashIdx) {
-      // Exactly one slash: "org/project" without log ID
-      throw new ContextError("Log ID", USAGE_HINT);
-    }
-
-    // Two+ slashes: split on last "/" → target + logId
-    const targetArg = first.slice(0, lastSlashIdx);
-    const logId = first.slice(lastSlashIdx + 1);
-
-    if (!logId) {
-      throw new ContextError("Log ID", USAGE_HINT);
-    }
-
+    const { id: logId, targetArg } = parseSlashSeparatedArg(
+      first,
+      "Log ID",
+      USAGE_HINT
+    );
     return { logId, targetArg };
   }
 

src/commands/trace/view.ts

@@ -7,7 +7,11 @@
 import { buildCommand } from "@stricli/core";
 import type { SentryContext } from "../../context.js";
 import { getDetailedTrace } from "../../lib/api-client.js";
-import { parseOrgProjectArg, spansFlag } from "../../lib/arg-parsing.js";
+import {
+  parseOrgProjectArg,
+  parseSlashSeparatedArg,
+  spansFlag,
+} from "../../lib/arg-parsing.js";
 import { openInBrowser } from "../../lib/browser.js";
 import { ContextError, ValidationError } from "../../lib/errors.js";
 import {
@@ -55,30 +59,11 @@ export function parsePositionalArgs(args: string[]): {
   }
 
   if (args.length === 1) {
-    const slashIdx = first.indexOf("/");
-
-    if (slashIdx === -1) {
-      // No slashes — plain trace ID
-      return { traceId: first, targetArg: undefined };
-    }
-
-    // Trace IDs are hex and never contain "/" — this must be a structured
-    // "org/project/traceId" or "org/project" (missing trace ID)
-    const lastSlashIdx = first.lastIndexOf("/");
-
-    if (slashIdx === lastSlashIdx) {
-      // Exactly one slash: "org/project" without trace ID
-      throw new ContextError("Trace ID", USAGE_HINT);
-    }
-
-    // Two+ slashes: split on last "/" → target + traceId
-    const targetArg = first.slice(0, lastSlashIdx);
-    const traceId = first.slice(lastSlashIdx + 1);
-
-    if (!traceId) {
-      throw new ContextError("Trace ID", USAGE_HINT);
-    }
-
+    const { id: traceId, targetArg } = parseSlashSeparatedArg(
+      first,
+      "Trace ID",
+      USAGE_HINT
+    );
     return { traceId, targetArg };
   }
 

src/lib/arg-parsing.ts

@@ -6,7 +6,7 @@
  * project list) and single-item commands (issue view, explain, plan).
  */
 
-import { ValidationError } from "./errors.js";
+import { ContextError, ValidationError } from "./errors.js";
 import type { ParsedSentryUrl } from "./sentry-url-parser.js";
 import { applySentryUrlContext, parseSentryUrl } from "./sentry-url-parser.js";
 import { isAllDigits } from "./utils.js";
@@ -345,6 +345,55 @@ function parseWithDash(arg: string): ParsedIssueArg {
   return { type: "project-search", projectSlug, suffix };
 }
 
+/**
+ * Parse a single positional arg that may be a plain hex ID or a slash-separated
+ * `org/project/id` pattern.
+ *
+ * Used by commands whose IDs are hex strings that never contain `/`
+ * (event, trace, log), making the pattern unambiguous:
+ * - No slashes → plain ID, no target
+ * - Exactly one slash → `org/project` without ID → throws {@link ContextError}
+ * - Two or more slashes → splits on last `/` → `targetArg` + `id`
+ *
+ * @param arg - The raw single positional argument
+ * @param idLabel - Human-readable ID label for error messages (e.g. `"Event ID"`)
+ * @param usageHint - Usage example shown in error messages
+ * @returns Parsed `{ id, targetArg }` — `targetArg` is `undefined` for plain IDs
+ * @throws {ContextError} When the arg contains exactly one slash (missing ID)
+ *   or ends with a trailing slash (empty ID segment)
+ */
+export function parseSlashSeparatedArg(
+  arg: string,
+  idLabel: string,
+  usageHint: string
+): { id: string; targetArg: string | undefined } {
+  const slashIdx = arg.indexOf("/");
+
+  if (slashIdx === -1) {
+    // No slashes — plain ID
+    return { id: arg, targetArg: undefined };
+  }
+
+  // IDs are hex and never contain "/" — this must be a structured
+  // "org/project/id" or "org/project" (missing ID)
+  const lastSlashIdx = arg.lastIndexOf("/");
+
+  if (slashIdx === lastSlashIdx) {
+    // Exactly one slash: "org/project" without ID
+    throw new ContextError(idLabel, usageHint);
+  }
+
+  // Two+ slashes: split on last "/" → target + id
+  const targetArg = arg.slice(0, lastSlashIdx);
+  const id = arg.slice(lastSlashIdx + 1);
+
+  if (!id) {
+    throw new ContextError(idLabel, usageHint);
+  }
+
+  return { id, targetArg };
+}
+
 export function parseIssueArg(arg: string): ParsedIssueArg {
   // 0. URL detection — extract issue ID from Sentry web URLs
   const urlParsed = parseSentryUrl(arg);