feat: add Canvas LMS skill for fetching courses and assignments (#3799)

Adds a Canvas LMS integration skill under optional-skills/productivity/canvas/
with a Python CLI wrapper (canvas_api.py) for listing courses and assignments
via personal access token auth.

Cherry-picked from PR #1250 by Alicorn-Max-S with:
- Moved from skills/ to optional-skills/ (niche educational integration)
- Fixed hardcoded ~/.hermes/ path to use $HERMES_HOME
- Removed Canvas env vars from .env.example (optional skill)
- Cleaned stale 'mini-swe-agent backend' reference from .env.example header

Co-authored-by: Alicorn-Max-S <Alicorn-Max-S@users.noreply.github.com>

.env.example

@@ -98,7 +98,7 @@ FAL_KEY=
 HONCHO_API_KEY=
 
 # =============================================================================
-# TERMINAL TOOL CONFIGURATION (mini-swe-agent backend)
+# TERMINAL TOOL CONFIGURATION
 # =============================================================================
 # Backend type: "local", "singularity", "docker", "modal", or "ssh"
 # Terminal backend is configured in ~/.hermes/config.yaml (terminal.backend).

optional-skills/productivity/canvas/SKILL.md

@@ -0,0 +1,97 @@
+---
+name: canvas
+description: Canvas LMS integration — fetch enrolled courses and assignments using API token authentication.
+version: 1.0.0
+author: community
+license: MIT
+prerequisites:
+  env_vars: [CANVAS_API_TOKEN, CANVAS_BASE_URL]
+metadata:
+  hermes:
+    tags: [Canvas, LMS, Education, Courses, Assignments]
+---
+
+# Canvas LMS — Course & Assignment Access
+
+Read-only access to Canvas LMS for listing courses and assignments.
+
+## Scripts
+
+- `scripts/canvas_api.py` — Python CLI for Canvas API calls
+
+## Setup
+
+1. Log in to your Canvas instance in a browser
+2. Go to **Account → Settings** (click your profile icon, then Settings)
+3. Scroll to **Approved Integrations** and click **+ New Access Token**
+4. Name the token (e.g., "Hermes Agent"), set an optional expiry, and click **Generate Token**
+5. Copy the token and add to `~/.hermes/.env`:
+
+```
+CANVAS_API_TOKEN=your_token_here
+CANVAS_BASE_URL=https://yourschool.instructure.com
+```
+
+The base URL is whatever appears in your browser when you're logged into Canvas (no trailing slash).
+
+## Usage
+
+```bash
+CANVAS="python $HERMES_HOME/skills/productivity/canvas/scripts/canvas_api.py"
+
+# List all active courses
+$CANVAS list_courses --enrollment-state active
+
+# List all courses (any state)
+$CANVAS list_courses
+
+# List assignments for a specific course
+$CANVAS list_assignments 12345
+
+# List assignments ordered by due date
+$CANVAS list_assignments 12345 --order-by due_at
+```
+
+## Output Format
+
+**list_courses** returns:
+```json
+[{"id": 12345, "name": "Intro to CS", "course_code": "CS101", "workflow_state": "available", "start_at": "...", "end_at": "..."}]
+```
+
+**list_assignments** returns:
+```json
+[{"id": 67890, "name": "Homework 1", "due_at": "2025-02-15T23:59:00Z", "points_possible": 100, "submission_types": ["online_upload"], "html_url": "...", "description": "...", "course_id": 12345}]
+```
+
+Note: Assignment descriptions are truncated to 500 characters. The `html_url` field links to the full assignment page in Canvas.
+
+## API Reference (curl)
+
+```bash
+# List courses
+curl -s -H "Authorization: Bearer $CANVAS_API_TOKEN" \
+  "$CANVAS_BASE_URL/api/v1/courses?enrollment_state=active&per_page=10"
+
+# List assignments for a course
+curl -s -H "Authorization: Bearer $CANVAS_API_TOKEN" \
+  "$CANVAS_BASE_URL/api/v1/courses/COURSE_ID/assignments?per_page=10&order_by=due_at"
+```
+
+Canvas uses `Link` headers for pagination. The Python script handles pagination automatically.
+
+## Rules
+
+- This skill is **read-only** — it only fetches data, never modifies courses or assignments
+- On first use, verify auth by running `$CANVAS list_courses` — if it fails with 401, guide the user through setup
+- Canvas rate-limits to ~700 requests per 10 minutes; check `X-Rate-Limit-Remaining` header if hitting limits
+
+## Troubleshooting
+
+| Problem | Fix |
+|---------|-----|
+| 401 Unauthorized | Token invalid or expired — regenerate in Canvas Settings |
+| 403 Forbidden | Token lacks permission for this course |
+| Empty course list | Try `--enrollment-state active` or omit the flag to see all states |
+| Wrong institution | Verify `CANVAS_BASE_URL` matches the URL in your browser |
+| Timeout errors | Check network connectivity to your Canvas instance |

optional-skills/productivity/canvas/scripts/canvas_api.py

@@ -0,0 +1,157 @@
+#!/usr/bin/env python3
+"""Canvas LMS API CLI for Hermes Agent.
+
+A thin CLI wrapper around the Canvas REST API.
+Authenticates using a personal access token from environment variables.
+
+Usage:
+  python canvas_api.py list_courses [--per-page N] [--enrollment-state STATE]
+  python canvas_api.py list_assignments COURSE_ID [--per-page N] [--order-by FIELD]
+"""
+
+import argparse
+import json
+import os
+import sys
+
+import requests
+
+CANVAS_API_TOKEN = os.environ.get("CANVAS_API_TOKEN", "")
+CANVAS_BASE_URL = os.environ.get("CANVAS_BASE_URL", "").rstrip("/")
+
+
+def _check_config():
+    """Validate required environment variables are set."""
+    missing = []
+    if not CANVAS_API_TOKEN:
+        missing.append("CANVAS_API_TOKEN")
+    if not CANVAS_BASE_URL:
+        missing.append("CANVAS_BASE_URL")
+    if missing:
+        print(
+            f"Missing required environment variables: {', '.join(missing)}\n"
+            "Set them in ~/.hermes/.env or export them in your shell.\n"
+            "See the canvas skill SKILL.md for setup instructions.",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
+
+def _headers():
+    return {"Authorization": f"Bearer {CANVAS_API_TOKEN}"}
+
+
+def _paginated_get(url, params=None, max_items=200):
+    """Fetch all pages up to max_items, following Canvas Link headers."""
+    results = []
+    while url and len(results) < max_items:
+        resp = requests.get(url, headers=_headers(), params=params, timeout=30)
+        resp.raise_for_status()
+        results.extend(resp.json())
+        params = None  # params are included in the Link URL for subsequent pages
+        url = None
+        link = resp.headers.get("Link", "")
+        for part in link.split(","):
+            if 'rel="next"' in part:
+                url = part.split(";")[0].strip().strip("<>")
+    return results[:max_items]
+
+
+# =========================================================================
+# Commands
+# =========================================================================
+
+
+def list_courses(args):
+    """List enrolled courses."""
+    _check_config()
+    url = f"{CANVAS_BASE_URL}/api/v1/courses"
+    params = {"per_page": args.per_page}
+    if args.enrollment_state:
+        params["enrollment_state"] = args.enrollment_state
+    try:
+        courses = _paginated_get(url, params)
+    except requests.HTTPError as e:
+        print(f"API error: {e.response.status_code} {e.response.text}", file=sys.stderr)
+        sys.exit(1)
+    output = [
+        {
+            "id": c["id"],
+            "name": c.get("name", ""),
+            "course_code": c.get("course_code", ""),
+            "enrollment_term_id": c.get("enrollment_term_id"),
+            "start_at": c.get("start_at"),
+            "end_at": c.get("end_at"),
+            "workflow_state": c.get("workflow_state", ""),
+        }
+        for c in courses
+    ]
+    print(json.dumps(output, indent=2))
+
+
+def list_assignments(args):
+    """List assignments for a course."""
+    _check_config()
+    url = f"{CANVAS_BASE_URL}/api/v1/courses/{args.course_id}/assignments"
+    params = {"per_page": args.per_page}
+    if args.order_by:
+        params["order_by"] = args.order_by
+    try:
+        assignments = _paginated_get(url, params)
+    except requests.HTTPError as e:
+        print(f"API error: {e.response.status_code} {e.response.text}", file=sys.stderr)
+        sys.exit(1)
+    output = [
+        {
+            "id": a["id"],
+            "name": a.get("name", ""),
+            "description": (a.get("description") or "")[:500],
+            "due_at": a.get("due_at"),
+            "points_possible": a.get("points_possible"),
+            "submission_types": a.get("submission_types", []),
+            "html_url": a.get("html_url", ""),
+            "course_id": a.get("course_id"),
+        }
+        for a in assignments
+    ]
+    print(json.dumps(output, indent=2))
+
+
+# =========================================================================
+# CLI parser
+# =========================================================================
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Canvas LMS API CLI for Hermes Agent"
+    )
+    sub = parser.add_subparsers(dest="command", required=True)
+
+    # --- list_courses ---
+    p = sub.add_parser("list_courses", help="List enrolled courses")
+    p.add_argument("--per-page", type=int, default=50, help="Results per page (default 50)")
+    p.add_argument(
+        "--enrollment-state",
+        default="",
+        help="Filter by enrollment state (active, invited_or_pending, completed)",
+    )
+    p.set_defaults(func=list_courses)
+
+    # --- list_assignments ---
+    p = sub.add_parser("list_assignments", help="List assignments for a course")
+    p.add_argument("course_id", help="Canvas course ID")
+    p.add_argument("--per-page", type=int, default=50, help="Results per page (default 50)")
+    p.add_argument(
+        "--order-by",
+        default="",
+        help="Order by field (due_at, name, position)",
+    )
+    p.set_defaults(func=list_assignments)
+
+    args = parser.parse_args()
+    args.func(args)
+
+
+if __name__ == "__main__":
+    main()