cmd acp silently ignores --mod / --mod-option (verified 1.82.1) #1017

Summary

cmd acp --mod ./x.ts exits 0 but never loads the mod. The flags are silently
dropped: no error, no warning, no [mods] entry in the debug log — including
for a nonexistent path, which normally warns "mod path not found". This also
breaks --mod-option, and leaves agent clients driving Chat over ACP with no
per-session system-prompt channel.

Expected Behavior

cmd acp --mod ./x.ts loads the mod exactly as the TUI does today
(cmd --mod ./x.ts), including appendSystemPrompt hooks and --mod-option
values for mod-declared flags. projectMods stays disabled under ACP.

Actual Behavior

The mod is never discovered or loaded. The debug log shows the args: line
then a bare subcommand: acp — no parsed options: line, no [mods] entry.
A bad path produces no warning. (User-scope ~/.commandcode/mods/ still loads
under ACP, so the engine supports mods here — only the flag forward is missing.)

Steps to reproduce

1. Create a sentinel mod at a temp path:

   export default function (cmd) {
     cmd.hooks({ appendSystemPrompt: () => 'REPRO-SENTINEL-1234' })
   }

2. Run A (valid mod), piping empty stdin so the process exits:
   DEBUG=true cmd acp --mod <sentinel> --skip-onboarding --no-auto-update --trust
3. Run B (bad path):
   DEBUG=true cmd acp --mod <tmp>/does-not-exist-xyz.ts --skip-onboarding --no-auto-update --trust
4. Read ~/.commandcode/logs/command.log, newest entries only.

Surface / entry path

ACP (cmd acp). TUI (cmd --mod) works — only ACP drops the flags.

Exact command

cmd acp --mod C:\Users\ACER\AppData\Local\Temp\opencode\cc-sandbox\sentinel-mod.ts --skip-onboarding --no-auto-update --trust

Debug log excerpt (1.82.1, DEBUG=true)

Run A — valid mod, never loaded:

02:29:53.024  > [Startup]  args: acp --mod ...\cc-sandbox\sentinel-mod.ts --skip-onboarding --no-auto-update --trust
02:29:53.368  - [cmd]      subcommand: acp
(nothing follows: no options: line, no [mods] entry for sentinel-mod.ts)

Run B — nonexistent path, no warning:

02:29:58.278  > [Startup]  args: acp --mod ...\cc-sandbox\does-not-exist-xyz.ts --skip-onboarding --no-auto-update --trust
02:29:58.618  - [cmd]      subcommand: acp
(nothing follows: no "mod path not found" warning)

Root cause (from shipped dist/cli.mjs)

1. createAcpCommand() declares no options — acp --help shows only --help,
   while the root command declares --mod <path> / --mod-option <name=value>.
2. runAcp() calls loadCommandModHost({ projectMods: !1 }) without ever
   calling setModPathsOverride() / setModOptionsOverride().
3. The only call site of those two setters is interactiveModeAction
   (n.mod && ... && setModPathsOverride(n.mod), n.modOption && ... && ...).

Suggested fix

In the ACP entry path, declare both flags (repeatable, same help text as the
root command) and forward them via setModPathsOverride() /
setModOptionsOverride() before loadCommandModHost() runs — mirroring
interactiveModeAction. Keep projectMods: !1. No-flag invocations must
behave byte-identically.

Environment

• Command Code version: 1.82.1 (also reproduced on 1.79.2)
• Operating system: Windows
• Shell: PowerShell 5.1

Additional context

session/new over ACP reads only cwd + mcpServers, ignoring _meta, so there
is currently no alternate per-session channel for what --mod provides.
Happy to verify candidate builds against the sentinel repro above.