fix(tmux): use pane PID to find correct opencode server port

lua/opencode/cli/server.lua

@@ -297,6 +297,19 @@ function M.get_port(launch)
   local Promise = require("opencode.promise")
 
   return Promise.new(function(resolve, reject)
+    -- Check if provider can supply port directly
+    local provider = require("opencode.config").provider
+    if provider and provider.get_port then
+      local provider_port = provider:get_port()
+      if provider_port then
+        local ok, _ = pcall(test_port, provider_port)
+        if ok then
+          resolve(provider_port)
+          return
+        end
+      end
+    end
+
     local configured_port = require("opencode.config").opts.port
     local find_port_fn = configured_port and function()
       return test_port(configured_port)

lua/opencode/provider/init.lua

@@ -31,6 +31,10 @@
 ---Should return `true` if the provider is available,
 ---else an error string and optional advice (for `vim.health.warn`).
 ---@field health? fun(): boolean|string, ...string|string[]
+---
+---Get the port of the `opencode` server started by this provider.
+---Returns `nil` if the provider cannot determine the port (falls back to CWD-based discovery).
+---@field get_port? fun(self: opencode.Provider): number|nil
 
 ---Configure and enable built-in providers.
 ---@class opencode.provider.Opts

lua/opencode/provider/kitty.lua

@@ -152,4 +152,9 @@ function Kitty:stop()
   end
 end
 
+---@return number|nil
+function Kitty:get_port()
+  return nil
+end
+
 return Kitty

lua/opencode/provider/snacks.lua

@@ -59,4 +59,9 @@ function Snacks:stop()
   end
 end
 
+---@return number|nil
+function Snacks:get_port()
+  return nil
+end
+
 return Snacks

lua/opencode/provider/terminal.lua

@@ -72,4 +72,9 @@ function Terminal:stop()
   end
 end
 
+---@return number|nil
+function Terminal:get_port()
+  return nil
+end
+
 return Terminal

lua/opencode/provider/tmux.lua

@@ -5,6 +5,9 @@
 ---
 ---The `tmux` pane ID where `opencode` is running (internal use only).
 ---@field pane_id? string
+---
+---Cached port of the `opencode` server (internal use only).
+---@field port? number
 local Tmux = {}
 Tmux.__index = Tmux
 Tmux.name = "tmux"
@@ -20,6 +23,7 @@ function Tmux.new(opts)
   local self = setmetatable({}, Tmux)
   self.opts = opts or {}
   self.pane_id = nil
+  self.port = nil
   return self
 end
 
@@ -85,7 +89,41 @@ function Tmux:stop()
   if pane_id then
     vim.fn.system("tmux kill-pane -t " .. pane_id)
     self.pane_id = nil
+    self.port = nil
   end
 end
 
+---Get the PID of the shell process running in the opencode pane.
+---@return number|nil pid
+function Tmux:get_pane_process_pid()
+  local pane_id = self:get_pane_id()
+  if not pane_id then
+    return nil
+  end
+
+  local output = vim.fn.system("tmux list-panes -t " .. pane_id .. " -F '#{pane_pid}'")
+  local pid = tonumber(vim.trim(output))
+  return pid
+end
+
+---Get the port of the opencode server started in this pane.
+---Traces from pane PID through descendants to find the listening port.
+---Caches the result for subsequent calls.
+---@return number|nil port
+function Tmux:get_port()
+  -- Return cached port if pane still exists
+  if self.port and self:get_pane_id() then
+    return self.port
+  end
+
+  local pane_pid = self:get_pane_process_pid()
+  if not pane_pid then
+    return nil
+  end
+
+  local process = require("opencode.util.process")
+  self.port = process.get_descendant_listening_port(pane_pid, 3)
+  return self.port
+end
+
 return Tmux

lua/opencode/provider/wezterm.lua

@@ -140,4 +140,9 @@ function Wezterm:stop()
   end
 end
 
+---@return number|nil
+function Wezterm:get_port()
+  return nil
+end
+
 return Wezterm

lua/opencode/util/process.lua

@@ -0,0 +1,60 @@
+---Process utilities for provider implementations.
+local M = {}
+
+---Get all descendant PIDs of a process (children, grandchildren, etc.)
+---@param pid number The parent process ID
+---@param max_depth? number Maximum recursion depth (default 3)
+---@return number[] pids List of descendant PIDs
+function M.get_descendants(pid, max_depth)
+  max_depth = max_depth or 3
+
+  local function recurse(current_pid, depth)
+    if depth > max_depth then
+      return {}
+    end
+
+    local children = {}
+    local output = vim.fn.system("pgrep -P " .. current_pid .. " 2>/dev/null")
+    for child_pid in output:gmatch("%d+") do
+      local child = tonumber(child_pid)
+      table.insert(children, child)
+      for _, descendant in ipairs(recurse(child, depth + 1)) do
+        table.insert(children, descendant)
+      end
+    end
+    return children
+  end
+
+  return recurse(pid, 1)
+end
+
+---Find the TCP port a process is listening on.
+---@param pid number The process ID
+---@return number|nil port The listening port, or nil if not found
+function M.get_listening_port(pid)
+  local lsof_output = vim.fn.system("lsof -w -iTCP -sTCP:LISTEN -P -n -a -p " .. pid .. " 2>/dev/null")
+  for line in lsof_output:gmatch("[^\r\n]+") do
+    local port = line:match(":(%d+)%s+%(LISTEN%)")
+    if port then
+      return tonumber(port)
+    end
+  end
+  return nil
+end
+
+---Find the listening port of any descendant of a process.
+---@param pid number The ancestor process ID
+---@param max_depth? number Maximum recursion depth (default 3)
+---@return number|nil port The listening port, or nil if not found
+function M.get_descendant_listening_port(pid, max_depth)
+  local descendants = M.get_descendants(pid, max_depth)
+  for _, desc_pid in ipairs(descendants) do
+    local port = M.get_listening_port(desc_pid)
+    if port then
+      return port
+    end
+  end
+  return nil
+end
+
+return M