fix(snapshot): use correct gitdir path and --cached diff

opencode stores the snapshot gitdir at {project_id}/{sha1(worktree)},
not {project_id} directly. All git ops were hitting the wrong repo.

Also switch diff/patch commands to --cached (matching opencode's impl)
and use --git-dir/--work-tree instead of -C to avoid ambiguity.

This should fix #384

Author: sudo-tee

lua/opencode/config_file.lua

@@ -40,6 +40,16 @@ M.get_opencode_project = Promise.async(function()
   return result --[[@as OpencodeProject|nil]]
 end)
 
+---Compute SHA1 of a string (used to match opencode's Hash.fast for worktree path)
+---@param str string
+---@return string|nil
+local function sha1(str)
+  local result = vim.system({ 'sh', '-c', 'printf "%s" "$1" | sha1sum', '_', str }):wait()
+  if result and result.code == 0 then
+    return vim.trim(result.stdout):match('^(%x+)')
+  end
+end
+
 ---Get the snapshot storage path for the current workspace
 ---@type fun(): Promise<string>
 M.get_workspace_snapshot_path = Promise.async(function()
@@ -48,7 +58,12 @@ M.get_workspace_snapshot_path = Promise.async(function()
     return ''
   end
   local home = vim.uv.os_homedir()
-  return home .. '/.local/share/opencode/snapshot/' .. project.id
+  local cwd = vim.fn.getcwd()
+  local worktree_hash = sha1(cwd)
+  if not worktree_hash then
+    return ''
+  end
+  return home .. '/.local/share/opencode/snapshot/' .. project.id .. '/' .. worktree_hash
 end)
 
 local _providers_render_callback = false

lua/opencode/git_review.lua

@@ -17,9 +17,10 @@ local function snapshot_git(cmd_args, opts)
     vim.notify('No snapshot path for the active session.')
     return nil, nil
   end
-  local args = { 'git', '-C', M.__snapshot_path }
+  local cwd = vim.fn.getcwd()
+  local args = { 'git', '--git-dir', M.__snapshot_path, '--work-tree', cwd }
   vim.list_extend(args, cmd_args)
-  local result = vim.system(args, opts or {}):wait()
+  local result = vim.system(args, opts or { cwd = cwd }):wait()
   if result and result.code == 0 then
     return vim.trim(result.stdout), result.stderr
   else
@@ -286,7 +287,9 @@ M.revert_selected_file = require_git_project(function(ref)
 end)
 
 M.revert_all = require_git_project(function(ref)
+  vim.print('⭕ ❱ git_review.lua:288 ❱ ƒ(anonymous) ❱ ref =', ref)
   M.__current_ref = ref or M.get_first_snapshot()
+  vim.print('⭕ ❱ git_review.lua:289 ❱ ƒ(M.__current_ref) ❱ M.__current_ref =', M.__current_ref)
 
   local files = get_changed_files()
 

lua/opencode/snapshot.lua

@@ -12,13 +12,14 @@ local session = require('opencode.session')
 ---@return string|nil, string|nil
 local function snapshot_git(cmd_args, opts)
   local snapshot_dir = config_file.get_workspace_snapshot_path():wait()
-  if not snapshot_dir then
+  if not snapshot_dir or snapshot_dir == '' then
     vim.notify('No snapshot path for the active session.')
     return nil, nil
   end
-  local args = { 'git', '-C', snapshot_dir }
+  local cwd = vim.fn.getcwd()
+  local args = { 'git', '--git-dir', snapshot_dir, '--work-tree', cwd }
   vim.list_extend(args, cmd_args)
-  local result = vim.system(args, opts or {}):wait()
+  local result = vim.system(args, opts or { cwd = cwd }):wait()
   if result and result.code == 0 then
     return vim.trim(result.stdout), nil
   else
@@ -133,7 +134,7 @@ function M.patch(hash)
     vim.notify('Failed to add files: ' .. add_err .. _, vim.log.levels.WARN)
   end
 
-  local files_output, diff_err = snapshot_git({ 'diff', '--name-only', hash, '--', '.' })
+  local files_output, diff_err = snapshot_git({ 'diff', '--cached', '--no-ext-diff', '--name-only', hash, '--', '.' })
   if not files_output then
     vim.notify('Failed to get diff: ' .. (diff_err or 'unknown error'), vim.log.levels.ERROR)
     return nil
@@ -160,7 +161,7 @@ function M.diff(hash)
     return nil
   end
 
-  local result, err = snapshot_git({ 'diff', hash, '--', '.' })
+  local result, err = snapshot_git({ 'diff', '--cached', '--no-ext-diff', hash, '--', '.' })
   if not result then
     vim.notify('Failed to get diff: ' .. (err or 'unknown error'), vim.log.levels.ERROR)
     return nil