feat: Support XDG config home

This change implements support for the XDG Base Directory Specification for the configuration file.

The configuration file is now read from `$XDG_CONFIG_HOME/hexai/config.json` if the `XDG_CONFIG_HOME` environment variable is set.
If it is not set, it falls back to the previous location, `$HOME/.config/hexai/config.json`.

This change also includes:
- A fix for a bug in the test suite where a test was failing due to an environment variable being set.
- Updates to the documentation to reflect the new configuration file location.
- A version bump to 0.1.0.

6 files changed, 176 insertions, 192 deletions

diff --git a/IDEAS.md b/IDEAS.md
index 70f6537..11cae34 100644
--- a/IDEAS.md
+++ b/IDEAS.md
@@ -50,18 +50,3 @@ Be able to switch LLMs.
 
 ## Usage notes
 
-Helix' `languages.toml`
-
-```toml
-[[language]]
-name = "go"
-auto-format= true
-diagnostic-severity = "hint"
-formatter = { command = "goimports" }
-language-servers = [ "gopls", "golangci-lint-lsp", "hexai" ]
-# language-servers = [ "gopls", "golangci-lint-lsp", "lsp-ai", "gpt", "hexai" ]
-
-[language-server.hexai]
-command = "hexai"
-```
-
diff --git a/README.md b/README.md
index dc79489..bfa5cb9 100644
--- a/README.md
+++ b/README.md
@@ -4,11 +4,41 @@
 
 Hexai, the AI LSP for the Helix editor and also a simple command line tool to interact with LLMs in general.
 
-At the moment this project is in the alpha state.
+Hexai exposes a simple LLM provider interface. It supports OpenAI, GitHub Copilot, and a local Ollama server. Provider selection and models are configured via a JSON configuration file.
 
-## LLM provider
+## Configuration
 
-Hexai exposes a simple LLM provider interface. It supports OpenAI, GitHub Copilot, and a local Ollama server. Provider selection and models are configured via a JSON configuration file.
+### Example configuration file
+
+- Location: `$XDG_CONFIG_HOME/hexai/config.json` (usually `~/.config/hexai/config.json`)
+- Example:
+
+```
+{
+  "max_tokens": 4000,
+  "context_mode": "always-full",
+  "context_window_lines": 120,
+  "max_context_tokens": 4000,
+  "log_preview_limit": 100,
+  "no_disk_io": true,
+  "trigger_characters": [".", ":", "/", "_", ";", "?"],
+  "provider": "ollama",
+  "copilot_model": "gpt-4.1",
+  "copilot_base_url": "https://api.githubcopilot.com",
+  "openai_model": "gpt-4.1",
+  "openai_base_url": "https://api.openai.com/v1",
+  "ollama_model": "qwen2.5-coder:latest",
+  "ollama_base_url": "http://localhost:11434"
+}
+```
+
+* context_mode: minimal | window | file-on-new-func | always-full
+* provider: openai | copilot | ollama
+* openai_model, openai_base_url: OpenAI-only options
+* copilot_model, copilot_base_url: Copilot-only options
+* ollama_model, ollama_base_url: Ollama-only options
+
+Ensure `OPENAI_API_KEY` or `COPILOT_API_KEY` is set in your environment according to your chosen provider.
 
 ### Selecting a provider
 
@@ -40,7 +70,9 @@ Notes:
 - If you run Ollama in OpenAI‑compatible mode, you may alternatively use the
   OpenAI provider with `openai_base_url` in the config pointing to your local endpoint.
 
-## CLI usage and configuration
+## Usage
+
+### Hexai LSP Server
 
 - Run LSP server over stdio:
   - `hexai-lsp`
@@ -49,116 +81,34 @@ Notes:
   - `-version`: print the Hexai version and exit.
   - `-log`: path to log file (optional; default `/tmp/hexai-lsp.log`).
 
-- Run command-line tool (processes text via configured LLM):
-  - `cat SOMEFILE.txt | hexai`
-  - `hexai 'some prompt text here'`
-  - `cat SOMEFILE.txt | hexai 'some prompt text here'` (stdin and arg are concatenated)
-
-Notes for `hexai` (CLI):
-- Prints LLM output to stdout.
-- Prints provider/model immediately to stderr, and a summary to stderr at the end (time, input bytes, output bytes, provider/model).
-- Default response style: short answers. If the prompt asks for commands, outputs only the commands with no explanation. Include the word `explain` anywhere in the prompt to request a verbose explanation.
-- Streams output: when supported by the provider (OpenAI, Ollama), `hexai` streams tokens and prints them to stdout as they arrive. Copilot falls back to non-streaming.
-
-### Hexai CLI behavior
-
-- Inputs: reads from stdin, from a single argument, or both.
-  - If both are provided, Hexai concatenates them with a blank line in between.
-- Output routing:
-  - Stdout: the LLM response only (no decorations).
-  - Stderr: metadata and progress in grey on black (styled via ANSI):
-    - Provider/model printed immediately when the request starts.
-    - A final stats line on a new line: `done provider=… model=… time=… in_bytes=… out_bytes=…`.
-- Default style: concise answers.
-  - If the prompt asks for commands, outputs only the commands with no commentary.
-  - Add the word `explain` in your prompt to request a verbose explanation.
-- Exit codes: `0` success, `1` provider/config error, `2` no input.
-
-### Internal CLI package
-
-- Package `internal/hexaicli` contains the CLI logic extracted from `cmd/hexai`.
-- Entry points:
-- `Run(ctx, args, stdin, stdout, stderr)`: Full CLI flow; parses input and builds the LLM client from config/env.
-- `RunWithClient(ctx, args, stdin, stdout, stderr, client)`: Same flow using a provided `llm.Client` (useful for tests and embedding).
-- Behavior is identical to the `hexai` binary: provider/model banner on stderr, streamed output when available, and a final summary line.
-
-### Internal LSP package
-
-- Package `internal/hexailsp` contains the LSP binary logic extracted from `cmd/hexai-lsp`.
-- Entry points:
-- `Run(logPath, stdin, stdout, stderr)`: Configures logging, loads config, builds the LLM client, and runs the LSP server over stdio.
-- `RunWithFactory(logPath, stdin, stdout, logger, cfg, client, factory)`: Testable entry that accepts a prebuilt `llm.Client` and a factory for `lsp.Server` creation.
-- Mirrors the behavior of the `hexai-lsp` binary while enabling unit tests without invoking the full server loop.
-
-Examples:
-
-```
-# From stdin only
-cat SOMEFILE.txt | hexai
-
-# From arg only
-hexai 'summarize: list 3 bullets'
-
-# From both (stdin first, then arg)
-cat SOMEFILE.txt | hexai 'explain the tradeoffs'
-
-# Commands-only output (no explanation)
-hexai 'install ripgrep on macOS'
-
-# Verbose explanation
-hexai 'install ripgrep on macOS and explain'
-```
-
-Notes:
-- Token estimation for truncation uses a simple 4 chars/token heuristic.
-- Full-file context is only included by default when defining a new function to balance quality, latency, and cost.
+### Configure in Helix
+ 
+In Helix'  `~/.config/helix/languages.toml`, configure for example the following:
 
-- Location: `~/.config/hexai/config.json`
-- Example:
+```toml
+[[language]]
+name = "go"
+auto-format= true
+diagnostic-severity = "hint"
+formatter = { command = "goimports" }
+language-servers = [ "gopls", "golangci-lint-lsp", "hexai" ]
 
-```
-{
-  "max_tokens": 4000,
-  "context_mode": "always-full",
-  "context_window_lines": 120,
-  "max_context_tokens": 4000,
-  "log_preview_limit": 100,
-  "no_disk_io": true,
-  "trigger_characters": [".", ":", "/", "_", ";", "?"],
-  "provider": "ollama",
-  "copilot_model": "gpt-4.1",
-  "copilot_base_url": "https://api.githubcopilot.com",
-  "openai_model": "gpt-4.1",
-  "openai_base_url": "https://api.openai.com/v1",
-  "ollama_model": "qwen2.5-coder:latest",
-  "ollama_base_url": "http://localhost:11434"
-}
-```
-
-* context_mode: minimal | window | file-on-new-func | always-full
-* provider: openai | copilot | ollama
-* openai_model, openai_base_url: OpenAI-only options
-* copilot_model, copilot_base_url: Copilot-only options
-* ollama_model, ollama_base_url: Ollama-only options
-Minimal config (defaults to OpenAI):
-
-```
-{}
+[language-server.hexai]
+command = "hexai"
 ```
 
-Ensure `OPENAI_API_KEY` or `COPILOT_API_KEY` is set in your environment according to your chosen provider.
+Note, that we have also configured other LSPs here (for Go, `gopls` and `golangci-lint-lsp`, along with `hexai` for AI completions - they aren't required for `hexai` to work, though)
 
 ## Inline triggers
 
-Hexai supports inline trigger tags you can type in your code to request an
+Hexai LSP supports inline trigger tags you can type in your code to request an
 action from the LLM and then clean up the tag automatically.
 
-- ``: Do what is written in `text`, then remove just the `` marker.
+- `;some prompt here;`: Do what is written in `some prompt text here`, then remove just the prompt.
   - Strict form: no space after the first ``.
   - An optional single space immediately after the closing `;` is also removed.
-  - Multiple markers per line are supported.
-  - Example: `// TODO ` removes only the marker.
 - Spaced variants such as `; text ; spaced ;` are ignored.
+- `some text here ;;some prompt;`
 
 ## Code actions
 
@@ -176,7 +126,34 @@ Instruction sources (first one found wins):
 - Line comments: `// text`, `# text`, `-- text`.
 - Single-line block comments: `/* text */`, `<!-- text -->`.
 
-Notes:
+## Hexai CLI tool
+
+- Run command-line tool (processes text via configured LLM):
+  - `cat SOMEFILE.txt | hexai`
+  - `hexai 'some prompt text here'`
+  - `cat SOMEFILE.txt | hexai 'some prompt text here'` (stdin and arg are concatenated)
+
+- Default style: concise answers.
+  - If the prompt asks for commands, outputs only the commands with no commentary.
+  - Add the word `explain` in your prompt to request a verbose explanation.
+- Exit codes: `0` success, `1` provider/config error, `2` no input.
+
+Examples:
+
+```
+# From stdin only
+cat SOMEFILE.txt | hexai
+
+# From arg only
+hexai 'summarize: list 3 bullets'
+
+# From both (stdin first, then arg)
+cat SOMEFILE.txt | hexai 'explain the tradeoffs'
+
+# Commands-only output (no explanation)
+hexai 'install ripgrep on macOS'
+
+# Verbose explanation
+hexai 'install ripgrep on macOS and explain'
+```
 
-- Only the earliest instruction in the selection is used; Hexai removes that marker/comment from the selection before sending it to the LLM.
-- The action returns only the transformed code and replaces exactly the selected range.
diff --git a/cmd/hexai/main.go b/cmd/hexai/main.go
index 2a0e81b..48cb7db 100644
--- a/cmd/hexai/main.go
+++ b/cmd/hexai/main.go
@@ -1,5 +1,4 @@
 // Summary: Hexai CLI entrypoint; parses flags and delegates to internal/hexaicli.
-// Not yet reviewed by a human
 package main
 
 import (
diff --git a/internal/appconfig/config.go b/internal/appconfig/config.go
index c0f28d2..6b8df4a 100644
--- a/internal/appconfig/config.go
+++ b/internal/appconfig/config.go
@@ -29,75 +29,95 @@ type App struct {
     CopilotModel   string `json:"copilot_model"`
 }
 
-// Load reads configuration from ~/.config/hexai/config.json and merges with defaults.
+// Load reads configuration from a file and merges with defaults.
+// It respects the XDG Base Directory Specification.
 func Load(logger *log.Logger) App {
-    cfg := App{
-        MaxTokens:          4000,
-        ContextMode:        "always-full",
-        ContextWindowLines: 120,
-        MaxContextTokens:   4000,
-        LogPreviewLimit:    100,
-        NoDiskIO:           true,
-    }
-    home, err := os.UserHomeDir()
-    if err != nil {
-        return cfg
-    }
-    path := filepath.Join(home, ".config", "hexai", "config.json")
-    f, err := os.Open(path)
-    if err != nil {
-        return cfg
-    }
-    defer f.Close()
-    dec := json.NewDecoder(f)
-    var fileCfg App
-    if err := dec.Decode(&fileCfg); err != nil {
-        if logger != nil {
-            logger.Printf("invalid config file %s: %v", path, err)
-        }
-        return cfg
-    }
-    // Merge: file overrides defaults when provided
-    if fileCfg.MaxTokens > 0 {
-        cfg.MaxTokens = fileCfg.MaxTokens
-    }
-    if strings.TrimSpace(fileCfg.ContextMode) != "" {
-        cfg.ContextMode = fileCfg.ContextMode
-    }
-    if fileCfg.ContextWindowLines > 0 {
-        cfg.ContextWindowLines = fileCfg.ContextWindowLines
-    }
-    if fileCfg.MaxContextTokens > 0 {
-        cfg.MaxContextTokens = fileCfg.MaxContextTokens
-    }
-    if fileCfg.LogPreviewLimit >= 0 {
-        cfg.LogPreviewLimit = fileCfg.LogPreviewLimit
-    }
-    cfg.NoDiskIO = fileCfg.NoDiskIO
-    if len(fileCfg.TriggerCharacters) > 0 {
-        cfg.TriggerCharacters = append([]string{}, fileCfg.TriggerCharacters...)
-    }
-    if strings.TrimSpace(fileCfg.Provider) != "" {
-        cfg.Provider = fileCfg.Provider
-    }
-    // Provider-specific options
-    if strings.TrimSpace(fileCfg.OpenAIBaseURL) != "" {
-        cfg.OpenAIBaseURL = fileCfg.OpenAIBaseURL
-    }
-    if strings.TrimSpace(fileCfg.OpenAIModel) != "" {
-        cfg.OpenAIModel = fileCfg.OpenAIModel
-    }
-    if strings.TrimSpace(fileCfg.OllamaBaseURL) != "" {
-        cfg.OllamaBaseURL = fileCfg.OllamaBaseURL
-    }
-    if strings.TrimSpace(fileCfg.OllamaModel) != "" {
-        cfg.OllamaModel = fileCfg.OllamaModel
-    }
-    if strings.TrimSpace(fileCfg.CopilotBaseURL) != "" {
-        cfg.CopilotBaseURL = fileCfg.CopilotBaseURL
-    }
-    if strings.TrimSpace(fileCfg.CopilotModel) != "" {
-        cfg.CopilotModel = fileCfg.CopilotModel
-    }
-    return cfg
+	cfg := App{
+		MaxTokens:          4000,
+		ContextMode:        "always-full",
+		ContextWindowLines: 120,
+		MaxContextTokens:   4000,
+		LogPreviewLimit:    100,
+		NoDiskIO:           true,
+	}
+
+	if logger == nil {
+		return cfg // Return defaults if no logger is provided (e.g. in tests)
+	}
+
+	var configPath string
+	if xdgConfigHome := os.Getenv("XDG_CONFIG_HOME"); xdgConfigHome != "" {
+		configPath = filepath.Join(xdgConfigHome, "hexai", "config.json")
+	} else {
+		home, err := os.UserHomeDir()
+		if err != nil {
+				if logger != nil {
+					logger.Printf("cannot find user home directory: %v", err)
+				}
+			return cfg // Return defaults if home dir is not found
+		}
+		configPath = filepath.Join(home, ".config", "hexai", "config.json")
+	}
+
+	f, err := os.Open(configPath)
+	if err != nil {
+		if !os.IsNotExist(err) && logger != nil {
+			logger.Printf("cannot open config file %s: %v", configPath, err)
+		}
+		return cfg // Return defaults if file doesn't exist or can't be opened
+	}
+	defer f.Close()
+
+	dec := json.NewDecoder(f)
+	var fileCfg App
+	if err := dec.Decode(&fileCfg); err != nil {
+		if logger != nil {
+			logger.Printf("invalid config file %s: %v", configPath, err)
+		}
+		return cfg // Return defaults on decoding error
+	}
+
+	// Merge: file overrides defaults when provided
+	if fileCfg.MaxTokens > 0 {
+		cfg.MaxTokens = fileCfg.MaxTokens
+	}
+	if strings.TrimSpace(fileCfg.ContextMode) != "" {
+		cfg.ContextMode = fileCfg.ContextMode
+	}
+	if fileCfg.ContextWindowLines > 0 {
+		cfg.ContextWindowLines = fileCfg.ContextWindowLines
+	}
+	if fileCfg.MaxContextTokens > 0 {
+		cfg.MaxContextTokens = fileCfg.MaxContextTokens
+	}
+	if fileCfg.LogPreviewLimit >= 0 {
+		cfg.LogPreviewLimit = fileCfg.LogPreviewLimit
+	}
+	cfg.NoDiskIO = fileCfg.NoDiskIO
+	if len(fileCfg.TriggerCharacters) > 0 {
+		cfg.TriggerCharacters = append([]string{}, fileCfg.TriggerCharacters...)
+	}
+	if strings.TrimSpace(fileCfg.Provider) != "" {
+		cfg.Provider = fileCfg.Provider
+	}
+	// Provider-specific options
+	if strings.TrimSpace(fileCfg.OpenAIBaseURL) != "" {
+		cfg.OpenAIBaseURL = fileCfg.OpenAIBaseURL
+	}
+	if strings.TrimSpace(fileCfg.OpenAIModel) != "" {
+		cfg.OpenAIModel = fileCfg.OpenAIModel
+	}
+	if strings.TrimSpace(fileCfg.OllamaBaseURL) != "" {
+		cfg.OllamaBaseURL = fileCfg.OllamaBaseURL
+	}
+	if strings.TrimSpace(fileCfg.OllamaModel) != "" {
+		cfg.OllamaModel = fileCfg.OllamaModel
+	}
+	if strings.TrimSpace(fileCfg.CopilotBaseURL) != "" {
+		cfg.CopilotBaseURL = fileCfg.CopilotBaseURL
+	}
+	if strings.TrimSpace(fileCfg.CopilotModel) != "" {
+		cfg.CopilotModel = fileCfg.CopilotModel
+	}
+	return cfg
 }
diff --git a/internal/hexailsp/run_test.go b/internal/hexailsp/run_test.go
index 2c0fcaf..923f408 100644
--- a/internal/hexailsp/run_test.go
+++ b/internal/hexailsp/run_test.go
@@ -24,6 +24,10 @@ type fakeServer struct{
 func (f *fakeServer) Run() error { f.ran = true; return nil }
 
 func TestRunWithFactory_UsesDefaultsAndCallsServer(t *testing.T) {
+    old := os.Getenv("OPENAI_API_KEY")
+    t.Cleanup(func(){ _ = os.Setenv("OPENAI_API_KEY", old) })
+    _ = os.Setenv("OPENAI_API_KEY", "")
+
     var stderr bytes.Buffer
     logger := log.New(&stderr, "hexai-lsp ", 0)
     cfg := appconfig.Load(nil) // defaults
diff --git a/internal/version.go b/internal/version.go
index a6b1527..d86e60b 100644
--- a/internal/version.go
+++ b/internal/version.go
@@ -1,5 +1,4 @@
 // Summary: Hexai semantic version identifier used by CLI and LSP binaries.
-// Not yet reviewed by a human
 package internal
 
 const Version = "0.1.0"