docs: add first-run initialization design spec

2026-06-06 22:47:46 -04:00
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+# First-Run Initialization Routine — Design Spec
+
+**Date:** 2026-06-07
+**Status:** Approved
+
+---
+
+## Goal
+
+Provide a mechanism for code/actions that should run exactly once — on the first interactive fish session after the config is installed or reset. Subsequent sessions skip all first-run logic entirely with zero overhead.
+
+---
+
+## Architecture
+
+### State detection
+
+A fish **universal variable** (`__fish_config_first_run_complete`) acts as the persistent flag. Universal variables survive shell exits and are stored in `~/.config/fish/fish_variables`. The flag is set to `1` immediately before any first-run actions execute, so a crash mid-run does not re-trigger next session.
+
+### File: `conf.d/first_run.fish`
+
+A single auto-sourced file in `conf.d/`. Fish loads all `conf.d/` files before `config.fish`, so this file cannot rely on PATH additions made in `config.fish`. That is acceptable: all first-run actions only need system-level binaries (`curl`, `fish`) that are in PATH unconditionally.
+
+### Guard pattern
+
+```fish
+if status is-interactive
+    if not set -q __fish_config_first_run_complete
+        set -U __fish_config_first_run_complete 1
+        # first-run actions here
+    end
+end
+```
+
+The `status is-interactive` guard prevents the routine from firing in scripts, completions, or subshells.
+
+---
+
+## First-Run Actions (in order)
+
+1. **Welcome message** — print a brief one-time greeting identifying the config and key commands.
+2. **Fisher bootstrap** — automatically install Fisher and all plugins from `fish_plugins` (replaces the interactive Y/n prompt currently in `config.fish`).
+3. **Theme** — apply `Catppuccin Mocha` via `fish_config theme choose`.
+
+---
+
+## Changes to `config.fish`
+
+The existing interactive Fisher bootstrap block (lines ~118–130) is removed. `first_run.fish` owns that responsibility. The `config.fish` block was guarded by `not type -q fisher`; the new file guards by the universal variable instead, which is cleaner and avoids re-prompting if Fisher is uninstalled manually.
+
+---
+
+## Reset mechanism
+
+To re-trigger first-run (e.g., for testing):
+
+```fish
+set -Ue __fish_config_first_run_complete
+```
+
+A commented-out version of this command is included at the top of `first_run.fish`.
+
+---
+
+## Error handling
+
+- Fisher install failure is surfaced to the user via stderr but does not abort the session.
+- Theme application is guarded: only runs if `fish_config` is available.
+- All first-run actions are wrapped in `if status is-interactive` to prevent execution in non-interactive contexts.
+
+---
+
+## Files changed
+
+| File | Change |
+|------|--------|
+| `conf.d/first_run.fish` | **New** — first-run guard and actions |
+| `config.fish` | Remove interactive Fisher bootstrap block (~lines 118–130) |
+
+---
+
+## Success criteria
+
+- First launch: welcome message printed, Fisher + plugins installed, theme set.
+- Second launch: nothing extra runs.
+- `set -Ue __fish_config_first_run_complete` followed by new shell re-triggers all actions.
+- Non-interactive shells (`fish -c "echo hi"`) are unaffected.