feat: Add Codex CLI compatibility

- Add agents/openai.yaml for Codex skill discovery
- Make SKILL.md script path portable (repo, Claude, Codex, agents dirs)
- Platform-neutral output text ("assistant" instead of "Claude")
- Sandbox-friendly cache/output dirs with env var overrides and tempdir fallback
- Add Codex installation docs to README

Inspired by PR #24 (el-analista) and PR #5 (jblwilliams).
Zero impact on existing Claude Code behavior.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/lib/cache.py

@@ -3,6 +3,7 @@
 import hashlib
 import json
 import os
+import tempfile
 from datetime import datetime, timezone
 from pathlib import Path
 from typing import Any, Optional
@@ -10,11 +11,23 @@ from typing import Any, Optional
 CACHE_DIR = Path.home() / ".cache" / "last30days"
 DEFAULT_TTL_HOURS = 24
 MODEL_CACHE_TTL_DAYS = 7
+MODEL_CACHE_FILE = CACHE_DIR / "model_selection.json"
 
 
 def ensure_cache_dir():
-    """Ensure cache directory exists."""
-    CACHE_DIR.mkdir(parents=True, exist_ok=True)
+    """Ensure cache directory exists. Supports env override and sandbox fallback."""
+    global CACHE_DIR, MODEL_CACHE_FILE
+    env_dir = os.environ.get("LAST30DAYS_CACHE_DIR")
+    if env_dir:
+        CACHE_DIR = Path(env_dir)
+        MODEL_CACHE_FILE = CACHE_DIR / "model_selection.json"
+
+    try:
+        CACHE_DIR.mkdir(parents=True, exist_ok=True)
+    except PermissionError:
+        CACHE_DIR = Path(tempfile.gettempdir()) / "last30days" / "cache"
+        MODEL_CACHE_FILE = CACHE_DIR / "model_selection.json"
+        CACHE_DIR.mkdir(parents=True, exist_ok=True)
 
 
 def get_cache_key(topic: str, from_date: str, to_date: str, sources: str) -> str:
@@ -112,8 +125,8 @@ def clear_cache():
                 pass
 
 
-# Model selection cache (longer TTL)
-MODEL_CACHE_FILE = CACHE_DIR / "model_selection.json"
+# Model selection cache (longer TTL) — MODEL_CACHE_FILE is set at module level
+# and updated by ensure_cache_dir() if env override or fallback is needed.
 
 
 def load_model_cache() -> dict:

scripts/lib/http.py

@@ -20,7 +20,7 @@ def log(msg: str):
         sys.stderr.flush()
 MAX_RETRIES = 3
 RETRY_DELAY = 1.0
-USER_AGENT = "last30days-skill/2.0 (Claude Code Skill)"
+USER_AGENT = "last30days-skill/2.1 (Assistant Skill)"
 
 
 class HTTPError(Exception):

scripts/lib/render.py

@@ -1,6 +1,8 @@
 """Output rendering for last30days skill."""
 
 import json
+import os
+import tempfile
 from pathlib import Path
 from typing import List, Optional
 
@@ -10,8 +12,17 @@ OUTPUT_DIR = Path.home() / ".local" / "share" / "last30days" / "out"
 
 
 def ensure_output_dir():
-    """Ensure output directory exists."""
-    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    """Ensure output directory exists. Supports env override and sandbox fallback."""
+    global OUTPUT_DIR
+    env_dir = os.environ.get("LAST30DAYS_OUTPUT_DIR")
+    if env_dir:
+        OUTPUT_DIR = Path(env_dir)
+
+    try:
+        OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    except PermissionError:
+        OUTPUT_DIR = Path(tempfile.gettempdir()) / "last30days" / "out"
+        OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
 
 
 def _assess_data_freshness(report: schema.Report) -> dict:
@@ -35,7 +46,7 @@ def _assess_data_freshness(report: schema.Report) -> dict:
 
 
 def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "none") -> str:
-    """Render compact output for Claude to synthesize.
+    """Render compact output for the assistant to synthesize.
 
     Args:
         report: Report data
@@ -61,7 +72,7 @@ def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "
 
     # Web-only mode banner (when no API keys)
     if report.mode == "web-only":
-        lines.append("**🌐 WEB SEARCH MODE** - Claude will search blogs, docs & news")
+        lines.append("**🌐 WEB SEARCH MODE** - assistant will search blogs, docs & news")
         lines.append("")
         lines.append("---")
         lines.append("**⚡ Want better results?** Add API keys to unlock Reddit & X data:")
@@ -204,7 +215,7 @@ def render_compact(report: schema.Report, limit: int = 15, missing_keys: str = "
             lines.append(f"  *{item.why_relevant}*")
             lines.append("")
 
-    # Web items (if any - populated by Claude)
+    # Web items (if any - populated by the assistant)
     if report.web_error:
         lines.append("### Web Results")
         lines.append("")
@@ -356,15 +367,15 @@ def render_full_report(report: schema.Report) -> str:
             lines.append(f"> {item.snippet}")
             lines.append("")
 
-    # Placeholders for Claude synthesis
+    # Placeholders for assistant synthesis
     lines.append("## Best Practices")
     lines.append("")
-    lines.append("*To be synthesized by Claude*")
+    lines.append("*To be synthesized by assistant*")
     lines.append("")
 
     lines.append("## Prompt Pack")
     lines.append("")
-    lines.append("*To be synthesized by Claude*")
+    lines.append("*To be synthesized by assistant*")
     lines.append("")
 
     return "\n".join(lines)

scripts/lib/ui.py

@@ -344,7 +344,7 @@ class ProgressDisplay:
     def end_web_only(self):
         """End web-only spinner."""
         if self.spinner:
-            self.spinner.stop(f"{Colors.GREEN}Web{Colors.RESET} Claude will search the web")
+            self.spinner.stop(f"{Colors.GREEN}Web{Colors.RESET} assistant will search the web")
 
     def show_web_only_complete(self):
         """Show completion for web-only mode."""
@@ -352,7 +352,7 @@ class ProgressDisplay:
         if IS_TTY:
             sys.stderr.write(f"\n{Colors.GREEN}{Colors.BOLD}✓ Ready for web search{Colors.RESET} ")
             sys.stderr.write(f"{Colors.DIM}({elapsed:.1f}s){Colors.RESET}\n")
-            sys.stderr.write(f"  {Colors.GREEN}Web:{Colors.RESET} Claude will search blogs, docs & news\n\n")
+            sys.stderr.write(f"  {Colors.GREEN}Web:{Colors.RESET} assistant will search blogs, docs & news\n\n")
         else:
             sys.stderr.write(f"✓ Ready for web search ({elapsed:.1f}s)\n")
         sys.stderr.flush()

scripts/lib/websearch.py

@@ -1,12 +1,12 @@
 """WebSearch module for last30days skill.
 
-NOTE: WebSearch uses Claude's built-in WebSearch tool, which runs INSIDE Claude Code.
-Unlike Reddit/X which use external APIs, WebSearch results are obtained by Claude
+NOTE: WebSearch uses the assistant's built-in web search tool, which runs inside the host environment.
+Unlike Reddit/X which use external APIs, web search results are obtained by the assistant
 directly and passed to this module for normalization and scoring.
 
 The typical flow is:
-1. Claude invokes WebSearch tool with the topic
-2. Claude passes results to parse_websearch_results()
+1. The assistant invokes its web search tool with the topic
+2. The assistant passes results to parse_websearch_results()
 3. Results are normalized into WebSearchItem objects
 """