# 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](state-model.md#resolving-a-pin-to-a-ref); amended:
the closest branch wins, see "Pin resolves to the closest branch").
**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), one
count per level: red for danger, then yellow for warn (amended: a single
count in the worst color made 1 error + 1 warning look like 2 errors; the
status column grew from 14 to 16 for the second count). 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,
`shift+→/←`, `L`/`H` (or `ctrl+→/←`) expand/collapse all (see [ux-guide.md](ux-guide.md#navigation)).
`←` 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 (superseded by D22)

**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 `stat`s 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.

## Copy path with `c` via OSC 52

`c` copies the selected submodule's absolute directory (optional
`submodule.Locator`; the relative path as fallback). The absolute path is
what a shell needs (`cd <paste>`). OSC 52 instead of a clipboard tool
(`xclip`, `pbcopy`): no external dependency and it works over SSH. The cost:
terminals that block OSC 52 copy nothing silently; the footer still says
`copied`, since the application can't know.

## Key groups: global, navigation, submodule

Keys that act on the selected submodule (copy path, later checkout, bump) are
shown in a palette in the detail pane, next to what they act on; global keys
(`?`, `q`) sit right in the footer. Where the pane can't show the palette
(hidden below 90 columns, or under 12 lines) the footer shows these keys
instead, so small terminals need no extra UI (no overlay or action menu).
Keys never depend on what is visible.

## Pin resolves to the closest branch

A pin on a pushed feature branch showed as diverged from `origin/main`,
because `branch = main` in `.gitmodules` won before any distance was looked
at. Now the closest branch containing the pin wins; the `.gitmodules`
branch, the upstream and the remote default branch only break ties (and are
always compared, even past the 16-branch cap). An unpushed pin compares only
those preferred refs, by commits on either side: scanning every branch's
merge base would be too slow. Cost: a pin on main far behind its tip shows a
younger branch that contains it if that branch's tip is closer, so "n behind
main" is no longer visible there; `via <rule>` still tells which ref it is.

## Filter: matches with ancestors, lives as long as the input

`/` filters by case-insensitive substring of the submodule path. Matches
keep their ancestors, shown expanded, because a nested submodule alone
would lose its context; the user's fold state is not touched, so closing the
filter restores it (plus the selection's ancestors, so the selection stays
visible). The filter exists exactly while the input line is open, and `esc`
closes both, so there is no hidden filter that makes the list look
incomplete. While typing, `j`/`k`/`q` are text; `enter` returns the keys to
the tree and keeps the filter, so a filtered list can be navigated with the
usual keys. A filtered-out selection moves to the next visible submodule
(previous if none follows) instead of the first, so the cursor stays near
where it was. This adds the `bubbles/textinput` dependency (and its
`atotto/clipboard` import).

## Staged pin is shown in the tree, but is not an issue

A staged pin was only visible in the detail pane, so the header's `1 pin
staged` could not be traced to a row, and `in sync  nothing to do` was
wrong for a submodule whose pin change still has to be committed. The tree
now shows it in the status column: blue `staged` replaces `in sync`; next to
an issue word it is a blue `●` (an issue wins the word, since the cell holds
one word, D3). It is not counted in `+n`, because `+n` and the header count
issues and a staged pin stays quiet (D4). A collapsed row shows `●` if a
staged pin is hidden below it (`Hidden.Staged`), placed before the `·k`
counts so truncation of the 16-column cell cuts the counts first.

## Superproject is selectable in the header

The state of the root repository was invisible: a submodule the current
branch no longer has stays on disk as an untracked repository, root files
can be modified, HEAD can be unpushed. The root becomes a node with an
empty path (the convention `Fetcher`/`Change` already use), selected on
startup, and the **header** is its row: it already holds the root's path,
branch and ahead/behind, and a tree row would cost a line and an indent
level for an item that is not part of the tree. Selecting the header shows
the usual detail pane; the header also shows the root's state word, so a
problem is visible while a submodule is selected.

- *Changes ignore submodules* (`--ignore-submodules=all`): off-pin and staged
  pins already have their rows; counting them again would make the root
  `changed` in most real repositories.
- *Unpushed stays Danger*: same issue kind and level as a submodule, one
  rule for "work that exists only here" (D4).
- *The ref is the upstream*, not the closest branch: the header shows
  ahead/behind of the upstream, and "up to date" means relative to the
  tracked branch. A nearer feature branch would make the two disagree.
  Without an upstream the usual resolution applies.
- The root is not in `Walk`, so counts, fetch and loading logic stay
  submodule-only; the app tracks it by the path `""`.

## Problems only reuses the filter's tree reduction

`!` shows only submodules with issues. Instead of a second view, the tree's
filter got a second criterion: a submodule matches if its path contains the
term *and*, with problems only, it has an issue. Ancestors of matches stay as
context, expanded, so a danger deep in the tree is reachable without
unfolding anything. Unlike the filter text it is a mode that outlives the
filter line, so it has its own notice line above the footer: a short list
must not look like a healthy repository (D4). Loading and failed submodules
count as problems because their state is unknown (D7 counts `error` as danger
too); the cost is that rows vanish as statuses arrive, so the selection is
refitted after each status. Staged pins are not shown by it, since they are
not issues.

## D22 — Fetch only on request

**Context.** D18 fetched every repository on startup. With hundreds of
submodules that is hundreds of network round trips (and credential or
host-key failures) every time the tool opens, whether or not the user wants
fresh remote data.
**Decision.** Supersedes D18. Nothing is fetched on startup. The header and
the detail pane show the last fetch (`FETCH_HEAD`, also from fetches made in
other shells), so the user can judge how stale the remote refs are and press
`f` to fetch. The `--no-fetch` flag is removed with it (it still had the
side effect of switching off the update check; that has
`SUBMARINE_NO_UPDATE_CHECK`).
**Consequences.** Right after startup, `unpushed`, `↓n` and the like are as
fresh as the last fetch. `fetched never` appears for a repository that was
never fetched. The progress display and per-submodule fetch errors stay as
they are, they now belong to `f`.

## D23 — Restore: exact worktree, asks only for losses, may fetch what is missing

**Context.** The first write action had to give "the exact version of the
project my root commit specifies" in one key, without destroying work by
accident.
**Decision.** `x` restores the selection: reset to the target (HEAD for the
superproject, the index gitlink for a submodule, so a staged pin is kept and
used), remove untracked files and repositories, end merges/rebases, and do
the same for every submodule of the target tree, initializing missing ones.
- *Ignored files stay* (`clean` without `-x`): `.env`, `node_modules` and
  IDE settings are not "additional files" worth deleting in every submodule.
- *Branches never move.* A checkout that is not on the target is detached
  first, so commits stay on their branch.
- *It asks only if something is lost* (changed or untracked files,
  operations in progress, commits on no ref, standalone repositories).
  Never asking would delete repositories that exist nowhere else; always
  asking would train a reflexive `y` on the harmless cases. The loss is read
  from the disk when the key is pressed, not from the loaded statuses.
- *Network.* Supersedes the "network only in `Fetch`" rule (N8): restore may
  clone a missing submodule and fetch a missing commit, non-interactively and
  with a timeout, because "no child module missing" cannot be met offline.
- Key `x`, not `R`, which sits next to `r` (reload).
**Consequences.** `Restorer` is a new optional provider interface; the mock
does not implement it. Restore is idempotent and can be repeated after a
failure. It takes the time of its slowest clone; there is no per-repository
progress yet.