diff --git a/scripts/e2e/oca-codex-telegram-proof.ts b/scripts/e2e/oca-codex-telegram-proof.ts
index bc7b5d56..fae838a1 100644
--- a/scripts/e2e/oca-codex-telegram-proof.ts
+++ b/scripts/e2e/oca-codex-telegram-proof.ts
@@ -2,7 +2,9 @@
 import { spawn, spawnSync } from "node:child_process";
 import { createHash, randomUUID } from "node:crypto";
 import {
+  accessSync,
   chmodSync,
+  constants,
   copyFileSync,
   existsSync,
   mkdirSync,
@@ -386,12 +388,27 @@ export function resolveProofOutputDir(outputDir: string): string {
   return resolved;
 }
 
-function commandExists(command: string): boolean {
-  if (command.includes("/") || command.includes("\\")) return existsSync(expandHome(command));
-  const result = spawnSync("sh", ["-c", `command -v "$1" >/dev/null 2>&1`, "sh", command], {
-    stdio: "ignore",
+export function commandExists(command: string): boolean {
+  const pathEntries = process.env.PATH === undefined
+    ? (process.platform === "win32" ? [] : ["/usr/bin", "/bin"])
+    : process.env.PATH.split(path.delimiter).map((directory) => directory || ".");
+  const candidates = command.includes("/") || command.includes("\\")
+    ? [expandHome(command)]
+    : pathEntries.flatMap((directory) => {
+        const base = path.join(directory, command);
+        if (process.platform !== "win32") return [base];
+        const extensions = (process.env.PATHEXT ?? ".EXE;.CMD;.BAT;.COM").split(";").filter(Boolean);
+        return [base, ...extensions.map((extension) => `${base}${extension.toLowerCase()}`)];
+      });
+
+  return candidates.some((candidate) => {
+    try {
+      accessSync(candidate, constants.X_OK);
+      return statSync(candidate).isFile();
+    } catch {
+      return false;
+    }
   });
-  return result.status === 0;
 }
 
 function shellQuote(value: string): string {
diff --git a/src/config.ts b/src/config.ts
index 21eaad33..74f7724b 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -372,7 +372,11 @@ export function resolveAgentChannel(workdir: string): string | undefined {
   const mapping = pluginConfig.agentChannels;
   if (!mapping) return undefined;
 
-  const normalise = (p: string) => p.replace(/\/+$/, "");
+  const normalise = (p: string) => {
+    let end = p.length;
+    while (end > 0 && p[end - 1] === "/") end -= 1;
+    return p.slice(0, end);
+  };
   const normWorkdir = normalise(workdir);
 
   const entries = Object.entries(mapping).sort((a, b) => b[0].length - a[0].length);
diff --git a/tests/config.test.ts b/tests/config.test.ts
index 9e798273..d80d3b27 100644
--- a/tests/config.test.ts
+++ b/tests/config.test.ts
@@ -47,6 +47,12 @@ describe("resolveAgentChannel", () => {
     assert.equal(resolveAgentChannel("/home/user"), "telegram|bot1|123");
   });
 
+  it("normalizes long runs of trailing slashes in linear time", () => {
+    const trailingSlashes = "/".repeat(100_000);
+    setPluginConfig({ agentChannels: { [`/home/user${trailingSlashes}`]: "telegram|bot1|123" } });
+    assert.equal(resolveAgentChannel(`/home/user${trailingSlashes}`), "telegram|bot1|123");
+  });
+
   it("returns undefined for non-matching path", () => {
     setPluginConfig({ agentChannels: { "/home/user/project": "telegram|bot1|123" } });
     assert.equal(resolveAgentChannel("/other/path"), undefined);
diff --git a/tests/oca-codex-telegram-proof.test.ts b/tests/oca-codex-telegram-proof.test.ts
index 82b7568e..54098ddf 100644
--- a/tests/oca-codex-telegram-proof.test.ts
+++ b/tests/oca-codex-telegram-proof.test.ts
@@ -1,10 +1,11 @@
 import { describe, it } from "node:test";
 import assert from "node:assert/strict";
 import { execFileSync } from "node:child_process";
-import { existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { chmodSync, existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { delimiter, join } from "node:path";
 import {
+  commandExists,
   buildProofPlan,
   collectDoctorChecks,
   parseArgs,
@@ -102,6 +103,30 @@ describe("OCA Codex Telegram proof runner", () => {
     }
   });
 
+  it("checks executable paths without interpreting shell syntax", () => {
+    assert.equal(commandExists(process.execPath), true);
+    assert.equal(commandExists("definitely-missing-command; true"), false);
+  });
+
+  it("preserves POSIX empty PATH entries as the current directory", { skip: process.platform === "win32" }, () => {
+    const originalCwd = process.cwd();
+    const originalPath = process.env.PATH;
+    const directory = mkdtempSync(join(tmpdir(), "oca-proof-command-path-"));
+    const command = "oca-proof-local-command";
+    try {
+      writeFileSync(join(directory, command), "#!/bin/sh\nexit 0\n");
+      chmodSync(join(directory, command), 0o700);
+      process.chdir(directory);
+      process.env.PATH = `${delimiter}${originalPath ?? ""}`;
+      assert.equal(commandExists(command), true);
+    } finally {
+      process.chdir(originalCwd);
+      if (originalPath === undefined) delete process.env.PATH;
+      else process.env.PATH = originalPath;
+      rmSync(directory, { recursive: true, force: true });
+    }
+  });
+
   it("prints a redacted proof plan without exposing Convex secret values", () => {
     const originalSecret = process.env.OPENCLAW_QA_CONVEX_SECRET_CI;
     const originalSite = process.env.OPENCLAW_QA_CONVEX_SITE_URL;