v3.8.1: codebuff integration + restore all provider presets

- Add codebuff backend: free DeepSeek V4 Pro, V4 Flash, Kimi K2.6, MiniMax M2.7
- codebuff backend auto-manages agent run lifecycle (start/finish)
- Credential detection from ~/.config/manicode/credentials.json
- Model-to-agent routing for codebuff free tier
- Restore all provider presets (Command Code, Crof, OpenAdapter, OpenRouter, etc.)
- Fix endpoints.json overwritten with only AG X entries
- Version bump to 3.8.1
- 54 self-tests passing

src/codex-launcher-gui

@@ -26,11 +26,14 @@ model_catalog_json = ""
 """
 
 CHANGELOG = [
-    ("3.8.0", "2026-05-22", [
+    ("3.8.1", "2026-05-24", [
+        "Codebuff integration — free DeepSeek V4 Pro, V4 Flash, Kimi K2.6, MiniMax M2.7",
+        "Codebuff backend: auto agent-run lifecycle, credential detection, model routing",
+        "Restored all provider presets (Command Code, Crof, OpenAdapter, OpenRouter, etc.)",
         "AI Monitoring — self-healing watchdog with 3-tier response system",
         "HealthWatcher: monitors proxy health every 5s, auto-restarts on crash",
         "LogAnalyzer: tails debug logs for 18 failure signal patterns",
-        "Tier 1: 14 rule-based auto-recovery rules (< 1s response)",
+        "Tier 1: 14 rule-based auto-recovery rules (< 1 s response)",
         "Tier 2: Incident pattern store with success rate tracking",
         "Tier 3: AI diagnostic agent — configurable provider/model for novel failures",
         "30 fault types catalogued across 5 categories (A-E)",
@@ -315,6 +318,14 @@ PROVIDER_PRESETS = {
             "GLM-4-Flash", "GLM-4-FlashX", "GLM-Z1-Flash",
         ],
     },
+    "Codebuff (Free DeepSeek/Kimi)": {
+        "backend_type": "codebuff",
+        "base_url": "https://codebuff.com",
+        "models": [
+            "deepseek/deepseek-v4-pro", "deepseek/deepseek-v4-flash",
+            "moonshotai/kimi-k2.6", "minimax/minimax-m2.7",
+        ],
+    },
 }
 
 def safe_name(name):
@@ -327,6 +338,7 @@ def label_for_backend(backend_type):
         "openai-compat": "OpenAI-compatible",
         "anthropic": "Anthropic",
         "command-code": "Command Code",
+        "codebuff": "Codebuff (Free AI)",
         "native": "Native",
     }.get(backend_type, backend_type)
 
@@ -1672,7 +1684,7 @@ class LauncherWin(Gtk.Window):
         # header row
         hdr = Gtk.Box(spacing=8)
         vbox.pack_start(hdr, False, False, 0)
-        lbl = Gtk.Label(label="<b>Codex Launcher v3.8.0</b>")
+        lbl = Gtk.Label(label="<b>Codex Launcher v3.8.1</b>")
         lbl.set_use_markup(True)
         hdr.pack_start(lbl, False, False, 0)
         changelog_btn = Gtk.Button(label="Changelog")
@@ -2923,6 +2935,7 @@ class EditEndpointDialog(Gtk.Dialog):
         for val, lab in [("openai-compat", "OpenAI-compatible (needs proxy)"),
                           ("anthropic", "Anthropic (needs proxy)"),
                           ("command-code", "Command Code (needs proxy)"),
+                          ("codebuff", "Codebuff - Free DeepSeek/Kimi (needs proxy)"),
                           ("gemini-oauth-cli", "Gemini CLI OAuth (needs proxy)"),
                           ("gemini-oauth-antigravity", "Antigravity OAuth (needs proxy)"),
                           ("native", "Native OpenAI (no proxy)")]: