refactor(code-references): remove reliance on system prompt (#196)

* refactor(code-references): remove reliance on system prompt

- update the reference parser to be more generic instead of relying on a
  system prompt
- add edit/read files to the references

This should fix #194

* refactor: normalize file paths in formatter and test snapshots

- Update formatter to show relative paths when inside cwd, basename when outside
- Normalize file paths in replay test snapshots to be cwd-relative
- Update expected test data to use relative paths instead of absolute paths

* refactor(reference_picker): simplify and harden patterns

* Update lua/opencode/ui/reference_picker.lua

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update lua/opencode/types.lua

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update lua/opencode/ui/reference_picker.lua

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: sudo-tee

AGENTS.md

@@ -32,3 +32,32 @@
 - **Tests:** Place in `tests/minimal/`, `tests/unit/`, or `tests/replay/`. Manual/visual tests in `tests/manual/`.
 
 _Agentic coding agents must follow these conventions strictly for consistency and reliability._
+
+## File Reference Detection
+
+The plugin automatically detects file references in LLM responses and makes them navigable via the reference picker (`<leader>or` or `:Opencode references`).
+
+### Supported Formats
+
+The reference picker recognizes these file reference patterns:
+
+1. **Backtick-wrapped** (recommended by LLMs naturally):
+   - `` `path/to/file.lua` ``
+   - `` `path/to/file.lua:42` ``
+   - `` `path/to/file.lua:42:10` `` (with column)
+   - `` `path/to/file.lua:42-50` `` (line range)
+
+2. **file:// URIs** (backward compatibility):
+   - `file://path/to/file.lua`
+   - `file://path/to/file.lua:42`
+   - `file://path/to/file.lua:42-50`
+
+3. **Plain paths** (natural format):
+   - `path/to/file.lua`
+   - `path/to/file.lua:42`
+   - `./relative/path.lua:42`
+   - `/absolute/path.lua:42`
+
+All formats support both relative and absolute paths. Files must exist to be recognized (validation prevents false positives).
+
+**No system prompt configuration is required** - the parser works with all LLM providers, including those without system prompt support.

README.md

@@ -113,6 +113,7 @@ require('opencode').setup({
   preferred_completion = nil, -- 'blink', 'nvim-cmp','vim_complete' if nil, it will use the best available completion
   default_global_keymaps = true, -- If false, disables all default global keymaps
   default_mode = 'build', -- 'build' or 'plan' or any custom configured. @see [OpenCode Agents](https://opencode.ai/docs/modes/)
+  default_system_prompt = nil, -- Custom system prompt to use for all sessions. If nil, uses the default built-in system prompt
   keymap_prefix = '<leader>o', -- Default keymap prefix for global keymaps change to your preferred prefix and it will be applied to all keymaps starting with <leader>o
   opencode_executable = 'opencode', -- Name of your opencode binary
   keymap = {

lua/opencode/config.lua

@@ -10,6 +10,7 @@ M.defaults = {
   preferred_completion = nil,
   default_global_keymaps = true,
   default_mode = 'build',
+  default_system_prompt = nil,
   legacy_commands = true,
   keymap_prefix = '<leader>o',
   opencode_executable = 'opencode',

lua/opencode/core.lua

@@ -173,22 +173,9 @@ M.send_message = Promise.async(function(prompt, opts)
     state.current_mode = opts.agent
   end
 
-  params.system = [[
-# Code References
-
-**CRITICAL: Always use the file:// URI scheme when referencing files in responses AND wrap them in backticks.**
-
-Format: `file://path/to/file.lua`, `file://path/to/file.lua:42`, or `file://path/to/file.lua:42-50`
-
-Examples:
-- CORRECT: "The error is in `file://src/services/process.ts:712`"
-- INCORRECT: "The error is in file://src/services/process.ts:712"
-- INCORRECT: "The error is in src/services/process.ts:712"
-
-This matches the file:// URI format that the reference picker already parses from your responses, enabling automatic navigation.
-]]
-
   params.parts = context.format_message(prompt, opts.context):await()
+  params.system = opts.system or config.default_system_prompt or nil
+
   M.before_run(opts)
 
   local session_id = state.active_session.id

lua/opencode/types.lua

@@ -195,6 +195,7 @@
 ---@field preferred_completion 'blink' | 'nvim-cmp' | 'vim_complete' | nil -- Preferred completion strategy for mentons and commands
 ---@field default_global_keymaps boolean
 ---@field default_mode 'build' | 'plan' | string -- Default mode
+---@field default_system_prompt string | nil
 ---@field keymap_prefix string
 ---@field opencode_executable 'opencode' | string -- Command run for calling opencode
 ---@field keymap OpencodeKeymap
@@ -373,6 +374,7 @@
 ---@field model? string
 ---@field agent? string
 ---@field variant? string
+---@field system? string
 
 ---@class CompletionContext
 ---@field trigger_char string The character that triggered completion

lua/opencode/ui/formatter.lua

@@ -499,7 +499,18 @@ end
 ---@param input FileToolInput data for the tool
 ---@param metadata FileToolMetadata Metadata for the tool use
 function M._format_file_tool(output, tool_type, input, metadata)
-  local file_name = input and vim.fn.fnamemodify(input.filePath, ':t') or ''
+  local file_name = ''
+  if input and input.filePath then
+    local cwd = vim.fn.getcwd()
+    local absolute = vim.fn.fnamemodify(input.filePath, ':p')
+
+    if vim.startswith(absolute, cwd .. '/') then
+      file_name = absolute:sub(#cwd + 2)
+    else
+      file_name = absolute
+    end
+  end
+
   local file_type = input and util.get_markdown_filetype(input.filePath) or ''
   local tool_action_icons = { read = icons.get('read'), edit = icons.get('edit'), write = icons.get('write') }