fix(tmux): don't resolve an empty pane ID to an unrelated mission

[swade1987]

(This post authored by my AgenC)

Bug

agenc tmux resolve-mission was printing a real (but unrelated) mission UUID for pane IDs that should have resolved to nothing, in two related cases:

1. A genuinely empty pane ID (resolve-mission "").
2. A pane ID containing #, such as an accidentally-unexpanded tmux format placeholder passed in literally — e.g. resolve-mission "#{pane_id}" (this is what actually surfaced the bug for me, while building a tmux status-bar popup — see [Feature] tmux status-bar popup: mission ID + checkout directory for a window #32).

Root cause

Two distinct issues, same downstream symptom:

1. Empty pane ID falls through to the general mission list. handleListMissions only takes the pane-specific lookup path when tmux_pane is non-empty:

tmuxPane := r.URL.Query().Get("tmux_pane")
if tmuxPane != "" {
    mission, err := s.db.GetMissionByTmuxPane(tmuxPane)
    ...
}

An empty value falls through to the general mission-list endpoint instead. tmux resolve-mission then does fmt.Print(responses[0].ID) — printing whatever mission happens to be first in that unrelated list, rather than treating an empty pane ID as a lookup miss.

2. The pane ID isn't URL-escaped before being sent. The request URL is built via raw string concatenation: "/missions?tmux_pane="+paneID. A pane ID containing # has everything from # onward parsed as a URL fragment and silently dropped before the request is sent — confirmed directly with a standalone url.Parse of the exact string this command builds:

RawQuery: tmux_pane=
Fragment: {pane_id}

So the server receives an empty tmux_pane, hits issue #1's fallthrough, and this command prints an unrelated mission's ID again — the two bugs compound, and #2 is the more likely real-world trigger, since # is exactly what any accidentally-unexpanded tmux format placeholder looks like.

Fix

Two commits:

• Early return in runTmuxResolveMission when the pane ID is empty, before any server/database call.
• url.QueryEscape the pane ID before building the request URL, so a value containing # (or any other URL-special character) can no longer be silently truncated.

Verification

Built the binary from this branch and tested directly against a real local AgenC server/database:

$ agenc tmux resolve-mission ""
$                                      # nothing - fixed
$ agenc tmux resolve-mission "#{pane_id}"
$                                      # nothing - fixed (previously printed a real, unrelated mission UUID)
$ agenc tmux resolve-mission "%129"
61590b9a-bd96-4759-8654-fa3395dfa59a  # real pane still resolves correctly - no regression

Also ran go build ./... and go test ./cmd/... (both pass) from this branch.

[mieubrisse]

Oops that sounds like a bug; will get to this when I get my Claude chunking through issues