refactor(git): URI scheme is now a git revspec, loaded via cat-file -p

lua/git/cmd.lua

@@ -74,7 +74,7 @@ end
 ---@param path string
 local function show_file_in_split(worktree, user_ref, path)
     local label = repo.rev_parse(worktree, user_ref, true) or user_ref
-    local uri = "git://" .. label .. "//" .. path
+    local uri = "git://" .. label .. ":" .. path
     local buf = vim.fn.bufadd(uri)
     vim.b[buf].git_worktree = worktree
     vim.cmd("split " .. vim.fn.fnameescape(uri))
@@ -119,11 +119,7 @@ local function run_in_split(worktree, args, conf)
             vim.b[buf].git_parent_ref =
                 repo.rev_parse(worktree, user_ref .. "^", true)
         end
-        pcall(
+        pcall(vim.api.nvim_buf_set_name, buf, "git://" .. (sha or user_ref))
-            vim.api.nvim_buf_set_name,
-            buf,
-            "git://" .. (sha or user_ref) .. "//"
-        )
         vim.bo[buf].filetype = conf.ft
     else
         vim.bo[buf].filetype = conf.ft

lua/git/diff.lua

@@ -57,32 +57,31 @@ local function attach_index_writer(buf, worktree, path)
     })
 end
 
----Return a buffer holding the content at `<ref>:<path>`. `ref` is
+---Return a buffer holding the content addressed by a git revspec. The
----"index", "HEAD", or a commit revspec.
+---URI is `git://<revspec>` and BufReadCmd loads via `git cat-file -p`.
 ---@param worktree string
----@param ref string
+---@param revspec string  any revspec git understands (e.g. `HEAD:foo`, `:foo`, `:1:foo`, `<sha>`, `<sha>:foo`)
----@param path string
 ---@return integer
-function M.git_show_buf(worktree, ref, path)
+function M.git_show_buf(worktree, revspec)
-    local name = "git://" .. ref .. "//" .. path
+    local name = "git://" .. revspec
     local buf = vim.fn.bufadd(name)
     vim.b[buf].git_worktree = worktree
     vim.fn.bufload(buf)
     return buf
 end
 
----BufReadCmd handler for `git://<ref>//<path>` URIs. Worktree comes from
+---BufReadCmd handler for `git://<revspec>` URIs. Loads content via
----`vim.b[buf].git_worktree` if set, else from cwd. Ref of "index" maps
+---`git cat-file -p <revspec>`. Worktree comes from `vim.b[buf]
----to `git show :<path>`; "worktree" leaves the buffer empty (placeholder
+---.git_worktree` if set, else from cwd. Index entries (revspec form
----for missing files); anything else is a revspec.
+---`:<path>` for stage 0) are made writable via `attach_index_writer`,
+---so `:w` updates the index. Other revspecs are read-only.
 ---@param buf integer
 function M.read_uri(buf)
     local name = vim.api.nvim_buf_get_name(buf)
-    local ref, path = name:match("^git://(.-)//(.*)$")
+    local revspec = name:match("^git://(.+)$")
-    if not ref or path == "" then
+    if not revspec then
         return
     end
-    ---@cast path -nil
 
     local worktree = vim.b[buf].git_worktree or select(2, repo.resolve_cwd())
     if not worktree then
@@ -94,27 +93,26 @@ function M.read_uri(buf)
     vim.bo[buf].swapfile = false
     vim.bo[buf].bufhidden = "wipe"
 
-    if ref == "worktree" then
+    local stdout = util.exec(
-        vim.bo[buf].buftype = "nofile"
+        { "git", "cat-file", "-p", revspec },
-        vim.bo[buf].modifiable = false
+        { cwd = worktree }
-        vim.bo[buf].modified = false
+    )
-        vim.api.nvim_exec_autocmds("BufReadPost", { buffer = buf })
-        return
-    end
-
-    local revspec = ref == "index" and (":" .. path) or (ref .. ":" .. path)
-    local stdout = util.exec({ "git", "show", revspec }, { cwd = worktree })
     if stdout then
         vim.api.nvim_buf_set_lines(buf, 0, -1, false, util.split_lines(stdout))
     end
 
-    if ref == "index" then
+    -- Stage-0 index entries (`:<path>` with no further `:`) are
+    -- editable; `:w` rewrites the index entry via `attach_index_writer`.
+    -- Anything else (HEAD:, <sha>:, :1:, :2:, :3:, bare object refs)
+    -- is read-only.
+    local index_path = revspec:match("^:([^:]+)$")
+    if index_path then
         vim.bo[buf].buftype = "acwrite"
         -- Re-running BufReadCmd (e.g. on `:edit`) would otherwise stack
         -- another BufWriteCmd on the same buffer, so each `:w` runs
         -- hash-object + update-index N times.
         if not vim.b[buf].git_index_writer then
-            attach_index_writer(buf, worktree, path)
+            attach_index_writer(buf, worktree, index_path)
             vim.b[buf].git_index_writer = true
         end
     else
@@ -221,8 +219,9 @@ function M.split(opts)
         return
     end
 
-    local label = opts.ref == "" and "index" or opts.ref
+    -- Stage 0 (index) is `:<path>`; named refs are `<ref>:<path>`.
-    local uri = "git://" .. label .. "//" .. rel
+    local revspec = opts.ref == "" and (":" .. rel) or (opts.ref .. ":" .. rel)
+    local uri = "git://" .. revspec
     -- Stash the worktree on the buffer so the BufReadCmd handler doesn't
     -- fall back to cwd resolution (wrong when cwd != worktree).
     local buf = vim.fn.bufadd(uri)

lua/git/init.lua

@@ -63,7 +63,7 @@ function M.setup()
     end
     vim.filetype.add({
         pattern = {
-            ["git://.-//(.+)"] = function(_, bufnr, inner)
+            ["git://.*:([^:]+)$"] = function(_, bufnr, inner)
                 return vim.filetype.match({ filename = inner, buf = bufnr })
             end,
         },

lua/git/object.lua

@@ -87,11 +87,14 @@ end
 ---@param ref string  the commit ref the blob represents (e.g. `<sha>` or `<sha>^`)
 ---@return integer
 local function blob_buf(worktree, blob, path, ref)
-    local name = "git://" .. ref .. "//" .. path
+    local revspec = ref .. ":" .. path
     if is_zero(blob) then
-        return diff.empty_buf({ name = name, bufhidden = "hide" })
+        return diff.empty_buf({
+            name = "git://" .. revspec,
+            bufhidden = "hide",
+        })
     end
-    return diff.git_show_buf(worktree, ref, path)
+    return diff.git_show_buf(worktree, revspec)
 end
 
 ---@param worktree string
@@ -142,7 +145,7 @@ end
 function M.open_commit(worktree, ref, opts)
     local split = opts and opts.split
     local sha = repo.rev_parse(worktree, ref, true) or ref
-    local name = "git://" .. sha .. "//"
+    local name = "git://" .. sha
     local existing = vim.fn.bufnr(name)
     if existing ~= -1 and vim.api.nvim_buf_is_loaded(existing) then
         if split == false then
@@ -218,7 +221,7 @@ function M.open_object(worktree, ref, opts)
 
     local split = opts and opts.split
     local sha = repo.rev_parse(worktree, ref, true) or ref
-    local name = "git://" .. sha .. "//"
+    local name = "git://" .. sha
     local existing = vim.fn.bufnr(name)
     if existing ~= -1 and vim.api.nvim_buf_is_loaded(existing) then
         if split == false then
@@ -279,7 +282,8 @@ function M.open_under_cursor()
         line:match("^%d+ (%w+) (%x+)\t(.+)$")
     if entry_sha then
         if entry_type == "blob" then
-            local buf = diff.git_show_buf(ctx.worktree, ctx.ref, entry_name)
+            local buf =
+                diff.git_show_buf(ctx.worktree, ctx.ref .. ":" .. entry_name)
             vim.cmd.normal({ "m'", bang = true })
             vim.api.nvim_set_current_buf(buf)
         else

lua/git/show.lua

@@ -16,7 +16,7 @@ local M = {}
 function M.show(worktree, ref, opts)
     local split = opts and opts.split
     local sha = repo.rev_parse(worktree, ref, true) or ref
-    local name = "git://" .. sha .. "//"
+    local name = "git://" .. sha
     -- Commit SHAs are immutable so a previously-opened buffer is still
     -- valid. Reuse it instead of refetching.
     local existing = vim.fn.bufnr(name)

lua/git/sidebar.lua

@@ -484,15 +484,19 @@ end
 ---@return ow.Git.DiffSide
 local function head_pane(worktree, path)
     return {
-        buf = diff.git_show_buf(worktree, "HEAD", path),
+        buf = diff.git_show_buf(worktree, "HEAD:" .. path),
-        name = "git://HEAD//" .. path,
+        name = "git://HEAD:" .. path,
     }
 end
 
+---@param worktree string
 ---@param path string
 ---@return ow.Git.DiffSide
-local function head_empty_pane(path)
+local function absent_pane(worktree, path)
-    return { buf = diff.empty_buf(), name = "git://HEAD//" .. path }
+    return {
+        buf = diff.empty_buf(),
+        name = "[absent] " .. vim.fs.joinpath(worktree, path),
+    }
 end
 
 ---@param worktree string
@@ -505,12 +509,6 @@ local function worktree_pane(worktree, path)
     }
 end
 
----@param path string
----@return ow.Git.DiffSide
-local function worktree_empty_pane(path)
-    return { buf = diff.empty_buf(), name = "git://worktree//" .. path }
-end
-
 ---@param s ow.Git.SidebarState
 ---@param entry ow.Git.FileEntry
 ---@return ow.Git.DiffSide
@@ -519,10 +517,12 @@ local function index_pane(s, entry)
         entry.section == "Untracked"
         or (entry.section == "Staged" and entry.x == "D")
     )
+    if not in_index then
+        return absent_pane(s.worktree, entry.path)
+    end
     return {
-        buf = in_index and diff.git_show_buf(s.worktree, "index", entry.path)
+        buf = diff.git_show_buf(s.worktree, ":" .. entry.path),
-            or diff.empty_buf(),
+        name = "git://:" .. entry.path,
-        name = "git://index//" .. entry.path,
     }
 end
 
@@ -534,7 +534,7 @@ local function other_pane(s, entry)
     local worktree = s.worktree
     if entry.section == "Staged" then
         if entry.x == "A" then
-            return head_empty_pane(p)
+            return absent_pane(worktree, p)
         end
         if entry.x == "D" then
             return head_pane(worktree, p)
@@ -544,7 +544,7 @@ local function other_pane(s, entry)
     end
     if entry.section == "Unstaged" then
         if entry.y == "D" then
-            return worktree_empty_pane(p)
+            return absent_pane(worktree, p)
         end
         return worktree_pane(worktree, p)
     end