submarine/docs/decisions.md

Decision log

Each entry: context, decision, consequences. Newest last.

D1 — Show pins as ref + distance, not hashes

Context. Hashes don't tell users whether a pin is current. Decision. Resolve each pin to a ref and show the distance (origin/main ↓1). The resolution order is fixed and the applied rule is shown in the detail pane (see state-model.md). Consequences. Resolution is a heuristic; showing the rule keeps it transparent.

D2 — Compare three commits: pinned, checked out, tip

Context. The first mockup showed one branch for both the checkout and the pin, so a mismatch was invisible. Decision. Model all three commits. The tree's ref column always describes the pin; checkout drift is an issue (off pin). Consequences. The detail pane shows Pinned / Checkout / Tip rows.

D3 — Raw dimensions in the domain, summarized issues in the UI

Context. States are not mutually exclusive (a submodule can be off pin and dirty), but showing every dimension made rows noisy (14 symbols). Decision. Status stores independent dimensions. Status.Issues() summarizes them into five kinds with three levels. The tree shows only the most severe issue (+n); the detail pane shows all. Consequences. One place defines what a problem is; a git backend gets the same behavior for free.

D4 — Attention follows severity

Context. Healthy rows competed for attention with dangerous ones. Decision. Three levels: quiet (muted row, no word), warn (yellow), danger (red bold). Behind/ahead, staged pin and detached HEAD are quiet. Consequences. A long list reads as grey, with problems standing out.

D5 — Words instead of glyphs

Context. Symbols (≠ ✚ ○ ⚠ ●) were found unintuitive. Decision. Short words: unpushed, conflict, missing, off pin, changed (plus error). Symbols remain only for arrows and tree markers. Consequences. Status column is 14 columns wide; no legend needed.

D6 — "Unpushed pin" is the most severe state

Context. Committing a superproject whose pin isn't on any remote breaks everyone else's checkout. Decision. unpushed is Danger, listed first, and its ↑n is red.

D7 — Hidden issues bubble up to collapsed parents

Context. Only the first level is shown by default, so nested problems would be invisible. Decision. Collapsed parents show ·k (issues in all descendants), colored by the worst one. Problems in a child do not mark the parent itself as changed.

D8 — Collapsed by default, branch-first navigation

Decision. Only the first level is visible. → expands and enters the first child, ← collapses and goes to the parent, space toggles, ctrl+→/← expand/collapse all (see ux-guide.md). ← on an expanded node collapses it in place, so a node can be closed without leaving it. Remembered expansion is kept on collapse, but reset by "collapse all".

D9 — Directory headers are path groups, not nesting

Decision. Submodules are grouped by the directory of their path relative to the parent repo. Headers (src/, modules/) are muted, non-selectable, and skipped by navigation. Nesting is expressed by indentation under the parent submodule.

D10 — ANSI 16 colors

Context. Fixed 256-colors (e.g. violet 63) ignored the user's terminal theme and were unreadable on light backgrounds. Decision. Use ANSI 0–15 for all meaning (red, yellow, blue, cyan, grey, default foreground). Only background shades use AdaptiveColor. Detect the background before Bubble Tea starts.

D11 — Provider boundary and async loading

Decision. The UI accesses data only through submodule.Provider: Tree() for the fast structure, Status(path) per submodule, loaded concurrently with a spinner per row. The prototype uses a mock provider with artificial latency. Consequences. A git backend can be added without UI changes; the UI stays responsive with many submodules.

D12 — No network on startup (superseded by D18)

Decision. Work from local refs and show their age; fetching is an explicit action (f).

D13 — Mouse support via bubblezone

Decision. Keep mouse support (click to select/toggle, wheel to move) using bubblezone markers per row.

D14 — Git provider shells out to the git CLI

Context. The provider can use a Go library (go-git) or the git binary. Decision. Run git -C <dir> … with a fixed environment (GIT_TERMINAL_PROMPT=0, GIT_OPTIONAL_LOCKS=0, LC_ALL=C) and parse stable output formats (--porcelain=v2, custom --format). Consequences. Behaves exactly like the user's git (config, gitdir: files, worktrees, partial clones), no new dependency, fast on large repos. Requires git on PATH; one process per query.

D15 — Git provider semantics

Decision. The pin is the index gitlink, because that is what the next commit records and what submodule update checks out; a difference to HEAD is PinStaged. Worktree state uses --ignore-submodules=dirty, so dirt in a nested submodule doesn't mark its parent (consistent with D7). A pin whose commit isn't present locally is a loading error, not unpushed, because without the commit nothing can be said about it. --mock is no longer the default; submarine [dir] reads a real repository.

D16 — Bounded concurrency inside the provider

Context. The app starts one Status command per submodule at once (D11); with hundreds of submodules that would spawn thousands of git processes. Decision. The git provider limits concurrent Status calls to runtime.NumCPU() with a semaphore that respects ctx. Consequences. The UI stays unchanged; rows fill in steadily.

D17 — Change preview: flat letter list against HEAD

Context. changed doesn't tell users what they changed or why; they want to remember what they were doing in a submodule. Decision. Status.Changes lists the changed files against HEAD (staged and unstaged combined) with line counts. The detail pane shows them as a flat list with a colored status letter in front, like IDE source-control views, instead of group headers. Sorted by kind, then by size; the 10-line budget keeps one line for every kind present and summarizes the rest. Placed directly below the issue lines, because the pane is cut by height. One summary line for all files, then strictly one line per file with its own age: a second summary line ("+1 · edited 19m ago") read as if it belonged to the first file. Dirt inside nested submodules is ignored (D7); unstaged moves show as removed + untracked. Consequences. One extra git diff per dirty submodule, none for clean ones. Not included: staged/unstaged markers, diff bodies, stash count.

D18 — Background fetch on startup

Context. Without fetching, every answer is only as fresh as the user's last git fetch, which they rarely run in every submodule. Decision. Supersedes D12. Show the local state at once, then fetch the superproject and every initialized submodule in the background (all remotes, prune, no recursion: we fetch each repository ourselves, at most 8 at once). Fetches never prompt; they fail with git's message instead. --no-fetch disables it, f repeats it. Consequences. Startup still doesn't wait for the network (N1). A failed fetch is shown per submodule and counted in the header; it is not an issue (D3).

D19 — Watch git metadata by polling

Context. The view should follow changes made outside the application. File system events (fsnotify) need a dependency, one watch per directory (hundreds of repositories × ref directories hit inotify limits) and don't work on WSL's Windows drives or network file systems. Decision. Poll every 2 s: compare names, mtimes and sizes of each repository's git metadata (FETCH_HEAD, refs, HEAD, index, …), split into a remote, a local and a structure part. Consequences. Works everywhere, no dependency; a few stats per repository per poll; changes appear within about 2 s. Edits of worktree files are not detected (that would mean running git status everywhere every poll); r reloads on demand.

D20 — Refresh is driven by the repositories, not by our fetch

Decision. A finished fetch only updates its progress. Reloading is triggered solely by the watcher, so our own fetch and a fetch in another shell take the same path. Reloads keep the old state visible, run at most once per submodule at a time and coalesce bursts. Consequences. One mechanism to test and trust. After our fetch the data updates up to one poll interval later; the header shows "fetched just now" right away.

D21 — Distribution: local build, Gitea generic registry, curl | sh

Decision. Releases are built locally with make and uploaded with an access token to the Gitea generic package registry. Installation is a POSIX install.sh; sub is a symlink to submarine. Updates are submarine update, driven by a latest/VERSION pointer file. Rationale. The Gitea instance has no working runner. The generic registry needs no extra hosting and is publicly readable. A symlink keeps one binary to update. The pointer is uploaded last and lives in its own package so versions stay clean. Consequences. Integrity is a sha256 from the same host: it catches corrupt or partial downloads, not a compromised registry (no signatures). The update check is a deliberate, outside-the-provider network use: only on update and a once-a-day background check that can be disabled.