hermes config set does not write to .env, causing Discord authorization to silently fail

Summary

hermes config set DISCORD_ALLOWED_USERS <value> writes to config.yaml, but the Discord gateway authorization check reads from .env. This causes a silent mismatch where the user believes the setting is applied but the gateway rejects messages from the newly added user with no clear error to the end user.

Steps to Reproduce

1. Add a new Discord user ID via hermes config set:

   hermes config set DISCORD_ALLOWED_USERS "ID1,ID2"

2. Confirm the value appears in config.yaml:

   grep DISCORD_ALLOWED_USERS ~/.hermes/config.yaml
   # → DISCORD_ALLOWED_USERS: ID1,ID2

3. Restart the gateway:

   hermes gateway restart

4. Have the new user (ID2) send a message to the bot on Discord.

Expected Behavior

The new user (ID2) should be authorized and receive a response.

Actual Behavior

The gateway rejects the message silently from the new user's perspective. The server-side log shows:

WARNING: Unauthorized slash attempt: user=<name> id=<ID2> ... reason='user not in DISCORD_ALLOWED_USERS / DISCORD_ALLOWED_ROLES'

Meanwhile, ~/.hermes/.env still contains only the original value:

DISCORD_ALLOWED_USERS=ID1

The gateway reads DISCORD_ALLOWED_USERS from .env at runtime, not from config.yaml.

Root Cause

hermes config set writes exclusively to config.yaml. However, the Discord platform adapter reads DISCORD_ALLOWED_USERS (and likely other gateway-related keys) from .env. These two files are not synchronized by hermes config set, creating a silent split-brain configuration state.

Workaround

Manually update .env directly:

sed -i 's/^DISCORD_ALLOWED_USERS=.*/DISCORD_ALLOWED_USERS=ID1,ID2/' ~/.hermes/.env
hermes gateway restart

Suggested Fix

hermes config set should detect which file is the authoritative source for a given key and write there — or write to both files to keep them in sync. At minimum, hermes config set should warn the user when a key is set in config.yaml but the runtime reads it from .env.

Environment

• Hermes version: 2026.5.27 (27ae826)
• OS: Ubuntu (Linux)
• Platform: Discord gateway