Description

Six functions in bin/lib/onboard.js create temporary files with predictable names using Date.now() and Math.random().toString(36):

• probeOpenAiLikeEndpoint (line 666)
• probeAnthropicEndpoint (line 710)
• fetchNvidiaEndpointModels (line 856)
• fetchOpenAiLikeModels (line 910)
• fetchAnthropicModels (line 946)
• writeSandboxConfigSyncFile (line 527)

Math.random() is not cryptographically secure — its output is predictable from a known seed. Combined with Date.now() (millisecond precision), a local attacker can predict the filename and win a race to:

1. Create a symlink at the predicted path before the probe runs
2. Redirect curl output (which may contain API responses with model data) to an attacker-controlled location
3. For writeSandboxConfigSyncFile, inject a malicious script that gets piped into openshell sandbox connect

The same file already uses fs.mkdtempSync() securely in two other places (lines 1764 and 2680), making this an inconsistency rather than a missing capability.

Reproduction Steps

1. Read bin/lib/onboard.js line 666
2. Note the filename pattern: nemoclaw-probe-${Date.now()}-${Math.random()...}.json
3. Both Date.now() and Math.random() are predictable — Date.now() is millisecond-resolution wall clock, Math.random() uses xorshift128+ with a recoverable seed
4. An attacker on the same system can pre-create a symlink at the predicted path in /tmp

Expected Behavior

Temp files should use fs.mkdtempSync() which creates a directory with a cryptographically random suffix (via the OS mkdtemp syscall), preventing filename prediction.

Actual Behavior

Temp files use predictable names constructed from Date.now() + Math.random().

Environment

• Code review — applies to current main branch
• File: bin/lib/onboard.js

Debug Output

N/A — static analysis finding.

Logs

N/A

Checklist

• I confirmed this bug is reproducible
• I searched existing issues and this is not a duplicate