Configurable environment variables per workspace/worktree

[knowsuchagency]

idea / problem

Shells spawned for a workspace/worktree only inherit the herdr daemon's environment. There's no way to scope env vars to a workspace or worktree, so anything env-based has to be typed into the shell after creation (which races shell startup and any interactive prompt) or baked into global shell rc.

requested change

Let workspace.create and worktree.create accept an env map, applied to the environment of shells spawned in that workspace/worktree. CLI: a repeatable --env KEY=VALUE.

Socket API:

{"method":"worktree.create","params":{"workspace_id":"1","branch":"feat/x","env":{"MISE_TRUSTED_CONFIG_PATHS":"/home/me/wt/x","DEPLOY_ENV":"staging"}}}

CLI:

herdr worktree create --workspace 1 --branch feat/x --env DEPLOY_ENV=staging

why you (well, I) want this

• Pre-trust dir-hook tools without typing into the shell. MISE_TRUSTED_CONFIG_PATHS=<worktree> means mise never shows its "trust this config?" prompt — that prompt otherwise blocks the shell and eats the first characters of any command sent right after creation. (direnv etc. similar.)
• Per-workspace config that isn't a command: DEPLOY_ENV=staging, an API base URL, a scoped token, RUST_LOG, … set before the first prompt, no rc edits.
• Tools driving herdr can inject per-task context into the pane at creation.

Related to #394 (setup script per space) but distinct: a setup script runs commands; this just sets the environment at spawn — it avoids the typed-command race and covers cases that aren't "run a command" (and the two compose, since env is available to a setup script too).

Happy to implement if there's interest.

[joaopsazevedo]

I've also noticed that the environment variables passed via --env are available in the first workspace pane, but not in any additional panes.

My usage case is also "Tools driving herdr can inject per-task context into the pane at creation.".

I've got a tool that automatically creates tmux sessions with a specific environment, and it would be great to replace with creating herdr workspaces.

[OptimusFrags]

Totally correct, should be done