fix(coding-agent): rejected unknown continued session ids

Treated a UUID passed after --continue as an explicit session target so a missing id cannot fall back to the latest persisted session.

Signed-off-by: Christian Stewart <christian@aperture.us>

packages/coding-agent/CHANGELOG.md

@@ -67,6 +67,9 @@
 - Fixed native Windows binary compatibility on older Windows 10 CPUs by building the `omp-windows-x64.exe` release asset with a baseline x64 runtime instead of AVX2. (#5172)
 - Fixed `GenerateImage` rejecting OpenAI Codex-compatible proxy bearer keys when the token does not expose a `chatgpt-account-id`. (#5174)
 - Fixed context promotion documentation to accurately reflect the `contextPromotionTarget` runtime behavior and `contextPromotion.enabled` default. (#5163)
+### Fixed
+
+- Fixed `--continue <session-id>` falling back to an unrelated latest session when the requested session does not exist.
 
 ## [16.4.3] - 2026-07-11
 

packages/coding-agent/src/main.ts

@@ -634,6 +634,14 @@ async function getChangelogForDisplay(parsed: Args): Promise<string | undefined>
 	return undefined;
 }
 
+const SESSION_ID_ARG_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+
+function positionalContinueSessionId(parsed: Args): string | undefined {
+	if (!parsed.continue || parsed.resume || parsed.fork || parsed.messages.length !== 1) return undefined;
+	const message = parsed.messages[0]?.trim();
+	return message && SESSION_ID_ARG_RE.test(message) ? message : undefined;
+}
+
 /** Resolves CLI session flags into an existing, forked, in-memory, or cancelled session manager. */
 export async function createSessionManager(
 	parsed: Args,
@@ -663,6 +671,13 @@ export async function createSessionManager(
 	if (parsed.noSession) {
 		return SessionManager.inMemory();
 	}
+	const continueSessionArg = positionalContinueSessionId(parsed);
+	if (continueSessionArg) {
+		parsed.resume = continueSessionArg;
+		parsed.continue = false;
+		parsed.messages = [];
+	}
+
 	if (typeof parsed.resume === "string") {
 		const sessionArg = parsed.resume;
 		if (sessionArg.includes("/") || sessionArg.includes("\\") || sessionArg.endsWith(".jsonl")) {

packages/coding-agent/test/main-session-resolution-error.test.ts

@@ -6,14 +6,19 @@
  * `[Uncaught Exception]`.
  */
 import { describe, expect, it, vi } from "bun:test";
+import * as fsp from "node:fs/promises";
+import * as os from "node:os";
+import * as path from "node:path";
 import type { Args } from "@oh-my-pi/pi-coding-agent/cli/args";
 import type { Settings } from "@oh-my-pi/pi-coding-agent/config/settings";
 import { createSessionManager, SessionResolutionError, writeStartupNotice } from "@oh-my-pi/pi-coding-agent/main";
 import * as sessionListingModule from "@oh-my-pi/pi-coding-agent/session/session-listing";
+import { SessionManager } from "@oh-my-pi/pi-coding-agent/session/session-manager";
 
-function buildResumeArgs(resume: string): Args {
+function buildResumeArgs(resume: string, sessionDir?: string): Args {
 	return {
 		resume,
+		sessionDir,
 		messages: [],
 		fileArgs: [],
 		unknownFlags: new Map(),
@@ -21,6 +26,17 @@ function buildResumeArgs(resume: string): Args {
 	};
 }
 
+function buildContinueArgs(message: string, sessionDir?: string): Args {
+	return {
+		continue: true,
+		sessionDir,
+		messages: [message],
+		fileArgs: [],
+		unknownFlags: new Map(),
+		unrecognizedFlags: [],
+	};
+}
+
 function buildForkArgs(fork: string, noSession = false): Args {
 	return {
 		fork,
@@ -107,6 +123,51 @@ describe("createSessionManager — missing session (#2084)", () => {
 		}
 	});
 
+	it("rejects --resume with unknown id instead of falling back to latest persisted session", async () => {
+		const cwd = await fsp.mkdtemp(path.join(os.tmpdir(), "omp-resume-unknown-id-"));
+		const sessionDir = path.join(cwd, "sessions");
+		const missingId = "019ea530-ffff-7000-8000-000000000000";
+		try {
+			const latest = SessionManager.create(cwd, sessionDir);
+			latest.appendMessage({ role: "user", content: "newer persisted session", timestamp: Date.now() });
+			await latest.rewriteEntries();
+			const latestSessionId = latest.getSessionId();
+			expect(latestSessionId).not.toBe(missingId);
+
+			await expect(
+				createSessionManager(buildResumeArgs(missingId, sessionDir), cwd, stubSettings),
+			).rejects.toMatchObject({
+				name: "SessionResolutionError",
+				message: `Session "${missingId}" not found.`,
+				hint: expect.stringContaining("omp --resume"),
+			});
+		} finally {
+			await fsp.rm(cwd, { recursive: true, force: true });
+		}
+	});
+
+	it("rejects --continue followed by an unknown session id instead of falling back to latest", async () => {
+		const cwd = await fsp.mkdtemp(path.join(os.tmpdir(), "omp-continue-unknown-id-"));
+		const sessionDir = path.join(cwd, "sessions");
+		const missingId = "019ea530-ffff-7000-8000-000000000000";
+		try {
+			const latest = SessionManager.create(cwd, sessionDir);
+			latest.appendMessage({ role: "user", content: "latest should not be resumed", timestamp: Date.now() });
+			await latest.rewriteEntries();
+			expect(latest.getSessionId()).not.toBe(missingId);
+
+			await expect(
+				createSessionManager(buildContinueArgs(missingId, sessionDir), cwd, stubSettings),
+			).rejects.toMatchObject({
+				name: "SessionResolutionError",
+				message: `Session "${missingId}" not found.`,
+				hint: expect.stringContaining("omp --resume"),
+			});
+		} finally {
+			await fsp.rm(cwd, { recursive: true, force: true });
+		}
+	});
+
 	it("rejects --fork with SessionResolutionError carrying a usage hint", async () => {
 		vi.spyOn(sessionListingModule, "resolveResumableSession").mockResolvedValue(undefined);
 		try {