Initial commit: after-hours shift manager Slack bot

Slack Bolt app on Lambda for managing on-call shifts. Employees can pick up, drop, and swap shifts via /oncall commands. Changes update 3CX ring group 800 routing in real time for same-day shifts. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-09-30 07:53:11 +00:00 · 2026-04-03 18:32:32 -04:00 · 2026-04-03 18:32:32 -04:00 · 4d0cdb5cfb
commit 4d0cdb5cfb
12 changed files with 1020 additions and 0 deletions
--- a/.gitignore
+++ b/.gitignore
@ -0,0 +1,7 @@
+__pycache__/
+*.pyc
+.aws-sam/
+venv/
+.env
+samconfig.toml
+output.json
--- a/README.md
+++ b/README.md
@ -0,0 +1,72 @@
+# After-Hours Shift Manager
+
+Slack bot for managing after-hours on-call shifts at Sea Haven Industries. Employees can pick up, drop, and swap shifts directly from Slack. Changes automatically update 3CX ring group 800 routing.
+
+## How It Works
+
+A recurring weekly schedule assigns employees to after-hours phone duty (5pm-8am). Any unassigned day shows as **Available** in Slack with a pickup button. When someone picks up or drops a shift for today, the 3CX phone system is updated immediately. Future changes take effect when the 3CX scheduler runs at 8am.
+
+## Slack Commands
+
+| Command | Description |
+|---|---|
+| `/oncall` | Show this week's schedule |
+| `/oncall next` | Show next week's schedule |
+| `/oncall pick <date>` | Pick up an available shift |
+| `/oncall drop <date>` | Drop your shift (marks it available) |
+| `/oncall swap <date> @person` | Hand your shift to someone else |
+| `/oncall register <ext>` | Link your Slack account to your phone extension |
+| `/oncall roster` | Show all employees and their link status |
+| `/oncall help` | Show help |
+
+Dates accept: `today`, `tomorrow`, `monday`-`sunday`, `4/5`, `2026-04-05`
+
+## Architecture
+
+- **Runtime**: Python 3.12 on AWS Lambda (via API Gateway)
+- **Data**: DynamoDB single-table (`afterhours-shifts`)
+- **IaC**: AWS SAM (`template.yaml`)
+- **Slack**: Slack Bolt framework with `/oncall` slash command
+- **3CX Integration**: Invokes the `3cx-ring-group-scheduler` Lambda for same-day changes; the scheduler reads DynamoDB for future dates
+
+### DynamoDB Schema
+
+Single table with `PK` / `SK` keys:
+
+| PK | SK | Description |
+|---|---|---|
+| `ROSTER` | `<extension>` | Employee: name, extension, slack_user_id |
+| `WEEKLY` | `<DayName>` | Default weekly schedule: extension, name |
+| `OVERRIDE` | `<YYYY-MM-DD>` | Date override from pickup/drop (or `OPEN`) |
+| `CONFIG` | `CONFIG` | Settings: ring_group, fallback_extension |
+
+## Deployment
+
+See [SETUP.md](SETUP.md) for full deployment and Slack app creation instructions.
+
+Quick reference:
+
+```bash
+# Build and deploy
+sam build
+sam deploy --guided --stack-name afterhours-shift-manager --region us-east-1
+
+# Seed initial schedule data
+python scripts/seed_schedule.py
+```
+
+### SSM Parameters
+
+| Parameter | Description |
+|---|---|
+| `/afterhours-shift-manager/slack-bot-token` | Slack bot OAuth token (`xoxb-...`) |
+| `/afterhours-shift-manager/slack-signing-secret` | Slack app signing secret |
+| `/afterhours-shift-manager/channel-id` | Slack channel ID for notifications |
+
+## Weekly Auto-Post
+
+Every Monday at 7am ET, the bot posts the week's schedule to the configured channel with pickup buttons for any available shifts.
+
+## Related
+
+- [3cx-ring-scheduler](https://github.com/Sea-Haven-Industries/3cx-ring-scheduler) — the Lambda that updates 3CX ring group routing daily
--- a/SETUP.md
+++ b/SETUP.md
@ -0,0 +1,95 @@
+# After-Hours Shift Manager — Setup Guide
+
+## 1. Create a Slack App
+
+1. Go to [api.slack.com/apps](https://api.slack.com/apps) → **Create New App** → **From scratch**
+2. Name: `After-Hours Shift Manager`, pick your workspace
+3. Under **OAuth & Permissions**, add these **Bot Token Scopes**:
+   - `chat:write` — post messages to channels
+   - `commands` — register slash commands
+   - `chat:write.public` — post to channels the bot isn't in
+4. Under **Slash Commands**, create a new command:
+   - Command: `/oncall`
+   - Request URL: `(fill in after deploy — see step 4)`
+   - Short Description: `Manage after-hours on-call shifts`
+   - Usage Hint: `[schedule | pick <date> | drop <date> | swap <date> @person | register <ext> | roster | help]`
+5. Under **Interactivity & Shortcuts**, toggle **ON**:
+   - Request URL: same URL as the slash command (the `/slack/events` endpoint)
+6. **Install to Workspace** — approve the permissions
+7. Copy the **Bot User OAuth Token** (`xoxb-...`) and **Signing Secret** (under Basic Information)
+
+## 2. Store Secrets in SSM Parameter Store
+
+```bash
+aws ssm put-parameter \
+  --name "/afterhours-shift-manager/slack-bot-token" \
+  --type SecureString \
+  --value "xoxb-YOUR-BOT-TOKEN"
+
+aws ssm put-parameter \
+  --name "/afterhours-shift-manager/slack-signing-secret" \
+  --type SecureString \
+  --value "YOUR-SIGNING-SECRET"
+
+# Channel ID where the bot will post weekly schedules
+# (right-click channel in Slack → Copy link → the ID is the last segment)
+aws ssm put-parameter \
+  --name "/afterhours-shift-manager/channel-id" \
+  --type SecureString \
+  --value "C0XXXXXXX"
+```
+
+## 3. Deploy the Stack
+
+```bash
+# Build and deploy
+sam build
+sam deploy --guided --stack-name afterhours-shift-manager --region us-east-1
+
+# Note the SlackBotApiUrl output — you'll need it for step 4
+```
+
+## 4. Set the Slack Request URL
+
+After deploy, copy the `SlackBotApiUrl` from the SAM output. Go back to your Slack app settings:
+
+- **Slash Commands** → edit `/oncall` → set **Request URL** to the output URL
+- **Interactivity & Shortcuts** → set **Request URL** to the same URL
+
+## 5. Seed the Schedule
+
+```bash
+python scripts/seed_schedule.py
+```
+
+This populates the DynamoDB table with the employee roster and default weekly schedule.
+
+## 6. Invite the Bot & Register Users
+
+1. Create a channel (e.g. `#after-hours-shifts`) and invite the bot: `/invite @After-Hours Shift Manager`
+2. Each employee links their Slack account by running:
+   ```
+   /oncall register 114
+   ```
+   (using their own extension number)
+
+## 7. Update the 3CX Scheduler (optional)
+
+To have the 3CX scheduler read overrides from DynamoDB (so Slack-driven changes apply to future dates automatically), deploy the updated 3CX scheduler from the `feature/dynamodb-shift-integration` branch. See that branch's changes for details.
+
+Without this step, the Slack bot still works — it invokes the 3CX scheduler Lambda directly for same-day changes. Future-date overrides would only take effect if the scheduler reads DynamoDB.
+
+## Commands Reference
+
+| Command | Description |
+|---|---|
+| `/oncall` | Show this week's schedule |
+| `/oncall next` | Show next week's schedule |
+| `/oncall pick <date>` | Pick up a shift |
+| `/oncall drop <date>` | Drop your shift (marks it open) |
+| `/oncall swap <date> @person` | Hand your shift to someone else |
+| `/oncall register <ext>` | Link your Slack to your extension |
+| `/oncall roster` | Show all employees and their link status |
+| `/oncall help` | Show help |
+
+Dates can be: `today`, `tomorrow`, `monday`–`sunday`, `4/5`, `2026-04-05`
--- a/requirements.txt
+++ b/requirements.txt
@ -0,0 +1,2 @@
+slack_bolt>=1.18.0,<2.0
+boto3>=1.28.0
--- a/scripts/seed_schedule.py
+++ b/scripts/seed_schedule.py
@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+"""Seed the afterhours-shifts DynamoDB table with initial roster and schedule.
+
+Usage:
+    python scripts/seed_schedule.py                    # uses default table name
+    python scripts/seed_schedule.py --table my-table   # custom table name
+"""
+
+import argparse
+
+import boto3
+
+
+TABLE_NAME = "afterhours-shifts"
+
+ROSTER = [
+    {"extension": "100", "name": "Adam Moussa"},
+    {"extension": "111", "name": "Alyssa Ficarra"},
+    {"extension": "113", "name": "Sarah May"},
+    {"extension": "114", "name": "Ashley Fedner"},
+    {"extension": "115", "name": "Derrick Smith"},
+    {"extension": "116", "name": "Cindy Vallecillo"},
+]
+
+WEEKLY_SCHEDULE = {
+    "Monday": {"extension": "114", "name": "Ashley Fedner"},
+    "Tuesday": {"extension": "115", "name": "Derrick Smith"},
+    "Wednesday": {"extension": "114", "name": "Ashley Fedner"},
+    "Thursday": {"extension": "115", "name": "Derrick Smith"},
+    "Friday": {"extension": "116", "name": "Cindy Vallecillo"},
+    "Saturday": {"extension": "100", "name": "Fallback"},
+    "Sunday": {"extension": "100", "name": "Fallback"},
+}
+
+CONFIG = {
+    "ring_group": "800",
+    "fallback_extension": "100",
+}
+
+
+def seed(table_name: str):
+    dynamodb = boto3.resource("dynamodb")
+    table = dynamodb.Table(table_name)
+
+    print(f"Seeding table: {table_name}")
+
+    # Roster
+    for emp in ROSTER:
+        table.put_item(
+            Item={
+                "PK": "ROSTER",
+                "SK": emp["extension"],
+                "name": emp["name"],
+                "extension": emp["extension"],
+                "slack_user_id": "",
+            }
+        )
+        print(f"  Roster: Ext {emp['extension']} — {emp['name']}")
+
+    # Weekly schedule
+    for day, info in WEEKLY_SCHEDULE.items():
+        table.put_item(
+            Item={
+                "PK": "WEEKLY",
+                "SK": day,
+                "extension": info["extension"],
+                "name": info["name"],
+            }
+        )
+        print(f"  Weekly: {day} — {info['name']} (Ext {info['extension']})")
+
+    # Config
+    table.put_item(
+        Item={
+            "PK": "CONFIG",
+            "SK": "CONFIG",
+            **CONFIG,
+        }
+    )
+    print(f"  Config: ring_group={CONFIG['ring_group']}, fallback={CONFIG['fallback_extension']}")
+
+    print("\nDone! Employees should run `/oncall register <extension>` in Slack to link their accounts.")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--table", default=TABLE_NAME)
+    args = parser.parse_args()
+    seed(args.table)
--- a/src/init.py
+++ b/src/init.py
--- a/src/app.py
+++ b/src/app.py
@ -0,0 +1,295 @@
+"""Slack Bolt app — /oncall command handlers and interactive actions."""
+
+import json
+import logging
+import os
+import re
+from datetime import datetime, timedelta
+from zoneinfo import ZoneInfo
+
+import boto3
+from slack_bolt import App
+
+from src.blocks import (
+    build_help_blocks,
+    build_roster_blocks,
+    build_shift_change_message,
+    build_week_schedule,
+)
+from src.schedule import FALLBACK_EXTENSION, ShiftSchedule
+
+logger = logging.getLogger(__name__)
+EASTERN = ZoneInfo("America/New_York")
+
+DAY_NAMES = ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"]
+
+
+def parse_date(text: str) -> datetime | None:
+    """Parse flexible date input: today, tomorrow, day names, m/d, YYYY-MM-DD."""
+    now = datetime.now(EASTERN)
+    text = text.strip().lower()
+
+    if text == "today":
+        return now
+    if text == "tomorrow":
+        return now + timedelta(days=1)
+
+    if text in DAY_NAMES:
+        target = DAY_NAMES.index(text)
+        current = now.weekday()
+        delta = (target - current) % 7
+        if delta == 0:
+            delta = 7
+        return now + timedelta(days=delta)
+
+    for fmt in ("%Y-%m-%d", "%m/%d/%Y", "%m/%d", "%m-%d"):
+        try:
+            parsed = datetime.strptime(text, fmt)
+            if "%Y" not in fmt:
+                parsed = parsed.replace(year=now.year)
+                if parsed.replace(tzinfo=EASTERN) < now - timedelta(days=1):
+                    parsed = parsed.replace(year=now.year + 1)
+            return parsed.replace(tzinfo=EASTERN)
+        except ValueError:
+            continue
+
+    return None
+
+
+def invoke_3cx_scheduler(extension: str) -> None:
+    """Invoke the 3CX scheduler Lambda to update the ring group immediately."""
+    fn_name = os.environ.get("SCHEDULER_FUNCTION_NAME")
+    if not fn_name:
+        logger.warning("SCHEDULER_FUNCTION_NAME not set — skipping 3CX update")
+        return
+
+    client = boto3.client("lambda")
+    payload = {"force": True, "override_extension": extension}
+    logger.info("Invoking %s with %s", fn_name, payload)
+    client.invoke(
+        FunctionName=fn_name,
+        InvocationType="Event",  # async — don't wait
+        Payload=json.dumps(payload),
+    )
+
+
+def is_today(date_str: str) -> bool:
+    return date_str == datetime.now(EASTERN).strftime("%Y-%m-%d")
+
+
+def create_app(bot_token: str, signing_secret: str) -> App:
+    app = App(
+        token=bot_token,
+        signing_secret=signing_secret,
+        process_before_response=True,
+    )
+    schedule = ShiftSchedule()
+
+    # ── /oncall command ─────────────────────────────────────────────────
+
+    @app.command("/oncall")
+    def handle_oncall(ack, command, respond, client):
+        ack()
+        text = (command.get("text") or "").strip()
+        user_id = command["user_id"]
+        channel_id = command["channel_id"]
+
+        if not text or text == "schedule":
+            _show_schedule(respond, schedule)
+        elif text == "next":
+            _show_next_week(respond, schedule)
+        elif text == "help":
+            respond(blocks=build_help_blocks())
+        elif text == "roster":
+            respond(blocks=build_roster_blocks(schedule.get_roster()))
+        elif text.startswith("register"):
+            _handle_register(respond, schedule, user_id, text)
+        elif text.startswith("pick"):
+            _handle_pick(respond, schedule, user_id, text, channel_id, client)
+        elif text.startswith("drop"):
+            _handle_drop(respond, schedule, user_id, text, channel_id, client)
+        elif text.startswith("swap"):
+            _handle_swap(respond, schedule, user_id, text, channel_id, client)
+        else:
+            respond(text="Unknown command. Try `/oncall help`")
+
+    # ── Interactive button: pick up open shift ──────────────────────────
+
+    @app.action(re.compile(r"^pickup_"))
+    def handle_pickup_button(ack, body, client):
+        ack()
+        action_id = body["actions"][0]["action_id"]
+        date_str = action_id.replace("pickup_", "")
+        user_id = body["user"]["id"]
+        channel_id = body["channel"]["id"]
+
+        employee = schedule.get_employee_by_slack_id(user_id)
+        if not employee:
+            client.chat_postEphemeral(
+                channel=channel_id,
+                user=user_id,
+                text="You're not registered. Use `/oncall register <extension>` first.",
+            )
+            return
+
+        schedule.set_override(date_str, employee["extension"], employee["name"])
+
+        if is_today(date_str):
+            invoke_3cx_scheduler(employee["extension"])
+
+        blocks = build_shift_change_message(
+            user_id, date_str, "picked_up", employee["extension"], employee["name"]
+        )
+        client.chat_postMessage(channel=channel_id, blocks=blocks, text=f"Shift picked up for {date_str}")
+
+    # ── Subcommand handlers ─────────────────────────────────────────────
+
+    def _show_schedule(respond, schedule):
+        blocks = build_week_schedule(schedule)
+        respond(blocks=blocks)
+
+    def _show_next_week(respond, schedule):
+        now = datetime.now(EASTERN)
+        next_monday = now + timedelta(days=(7 - now.weekday()))
+        blocks = build_week_schedule(schedule, start_date=next_monday)
+        respond(blocks=blocks)
+
+    def _handle_register(respond, schedule, user_id, text):
+        parts = text.split()
+        if len(parts) < 2:
+            respond(text="Usage: `/oncall register <extension>`  (e.g. `/oncall register 114`)")
+            return
+
+        ext = parts[1].strip()
+        employee = schedule.register_user(user_id, ext)
+        if not employee:
+            respond(text=f"Extension {ext} not found in the roster. Check `/oncall roster`.")
+            return
+
+        respond(text=f"Linked your account to *{employee['name']}* (Ext {ext}).")
+
+    def _handle_pick(respond, schedule, user_id, text, channel_id, client):
+        parts = text.split(maxsplit=1)
+        if len(parts) < 2:
+            respond(text="Usage: `/oncall pick <date>`  (e.g. `/oncall pick friday`)")
+            return
+
+        employee = schedule.get_employee_by_slack_id(user_id)
+        if not employee:
+            respond(text="You're not registered. Use `/oncall register <extension>` first.")
+            return
+
+        date = parse_date(parts[1])
+        if not date:
+            respond(text=f"Couldn't parse date: `{parts[1]}`. Try: today, tomorrow, friday, 4/5, 2026-04-05")
+            return
+
+        date_str = date.strftime("%Y-%m-%d")
+        day_name = date.strftime("%A")
+        ext, name, source = schedule.resolve_shift(date_str, day_name)
+
+        # Already assigned to someone else (not open)
+        if source in ("weekly", "override") and ext != FALLBACK_EXTENSION:
+            respond(text=f"That shift is already covered by {name} (Ext {ext}). They'd need to drop it first.")
+            return
+
+        schedule.set_override(date_str, employee["extension"], employee["name"])
+
+        if is_today(date_str):
+            invoke_3cx_scheduler(employee["extension"])
+
+        blocks = build_shift_change_message(
+            user_id, date_str, "picked_up", employee["extension"], employee["name"]
+        )
+        client.chat_postMessage(channel=channel_id, blocks=blocks, text=f"Shift picked up for {date_str}")
+        respond(text=f"You picked up the shift for *{date.strftime('%A, %b %-d')}*.")
+
+    def _handle_drop(respond, schedule, user_id, text, channel_id, client):
+        parts = text.split(maxsplit=1)
+        if len(parts) < 2:
+            respond(text="Usage: `/oncall drop <date>`  (e.g. `/oncall drop friday`)")
+            return
+
+        employee = schedule.get_employee_by_slack_id(user_id)
+        if not employee:
+            respond(text="You're not registered. Use `/oncall register <extension>` first.")
+            return
+
+        date = parse_date(parts[1])
+        if not date:
+            respond(text=f"Couldn't parse date: `{parts[1]}`. Try: today, tomorrow, friday, 4/5, 2026-04-05")
+            return
+
+        date_str = date.strftime("%Y-%m-%d")
+        day_name = date.strftime("%A")
+        ext, name, source = schedule.resolve_shift(date_str, day_name)
+
+        if ext != employee["extension"]:
+            respond(text=f"That's not your shift — it belongs to {name} (Ext {ext}).")
+            return
+
+        schedule.mark_open(date_str)
+
+        if is_today(date_str):
+            invoke_3cx_scheduler(FALLBACK_EXTENSION)
+
+        blocks = build_shift_change_message(user_id, date_str, "dropped", ext, name)
+        client.chat_postMessage(channel=channel_id, blocks=blocks, text=f"Shift dropped for {date_str}")
+        respond(text=f"You dropped the shift for *{date.strftime('%A, %b %-d')}*. It's now open for pickup.")
+
+    def _handle_swap(respond, schedule, user_id, text, channel_id, client):
+        # Expected format: swap <date> @user  OR  swap <date> <extension>
+        parts = text.split(maxsplit=2)
+        if len(parts) < 3:
+            respond(text="Usage: `/oncall swap <date> @person`  (e.g. `/oncall swap friday @sarah`)")
+            return
+
+        employee = schedule.get_employee_by_slack_id(user_id)
+        if not employee:
+            respond(text="You're not registered. Use `/oncall register <extension>` first.")
+            return
+
+        date = parse_date(parts[1])
+        if not date:
+            respond(text=f"Couldn't parse date: `{parts[1]}`.")
+            return
+
+        date_str = date.strftime("%Y-%m-%d")
+        day_name = date.strftime("%A")
+        ext, name, source = schedule.resolve_shift(date_str, day_name)
+
+        if ext != employee["extension"]:
+            respond(text=f"That's not your shift — it belongs to {name} (Ext {ext}). You can only swap your own shifts.")
+            return
+
+        # Resolve target user — could be <@U12345> or an extension number
+        target_text = parts[2].strip()
+        slack_id_match = re.match(r"<@(\w+)(?:\|[^>]*)?>", target_text)
+        if slack_id_match:
+            target_slack_id = slack_id_match.group(1)
+            target = schedule.get_employee_by_slack_id(target_slack_id)
+            if not target:
+                respond(text=f"<@{target_slack_id}> isn't registered. They need to run `/oncall register <extension>`.")
+                return
+        else:
+            target = schedule.get_employee_by_extension(target_text)
+            if not target:
+                respond(text=f"Extension `{target_text}` not found in the roster.")
+                return
+
+        schedule.set_override(date_str, target["extension"], target["name"])
+
+        if is_today(date_str):
+            invoke_3cx_scheduler(target["extension"])
+
+        blocks = build_shift_change_message(
+            target.get("slack_user_id", user_id),
+            date_str,
+            "swapped",
+            target["extension"],
+            target["name"],
+        )
+        client.chat_postMessage(channel=channel_id, blocks=blocks, text=f"Shift swapped for {date_str}")
+        respond(text=f"Swapped *{date.strftime('%A, %b %-d')}* to {target['name']} (Ext {target['extension']}).")
+
+    return app
--- a/src/blocks.py
+++ b/src/blocks.py
@ -0,0 +1,126 @@
+"""Slack Block Kit message builders for shift schedule display."""
+
+from datetime import datetime, timedelta
+from zoneinfo import ZoneInfo
+
+EASTERN = ZoneInfo("America/New_York")
+
+DAY_ORDER = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]
+
+
+def _format_shift_line(date: datetime, ext: str, name: str, source: str, is_today: bool) -> str:
+    day_label = date.strftime("%a %b %-d")
+    if is_today:
+        day_label = f"*{day_label} (today)*"
+
+    if source == "available":
+        return f":large_yellow_circle:  {day_label} — *Available*"
+    if source == "override":
+        return f":large_blue_circle:  {day_label} — {name} (Ext {ext}) _[picked up]_"
+    return f":white_circle:  {day_label} — {name} (Ext {ext})"
+
+
+def build_week_schedule(schedule, start_date: datetime | None = None) -> list[dict]:
+    """Build Block Kit blocks showing the week's schedule.
+
+    Args:
+        schedule: ShiftSchedule instance
+        start_date: Monday of the week to show. Defaults to current week's Monday.
+    """
+    now = datetime.now(EASTERN)
+    if start_date is None:
+        start_date = now - timedelta(days=now.weekday())  # Monday of this week
+    start_date = start_date.replace(hour=0, minute=0, second=0, microsecond=0)
+
+    today_str = now.strftime("%Y-%m-%d")
+    week_label = start_date.strftime("%b %-d")
+    end_label = (start_date + timedelta(days=6)).strftime("%b %-d")
+
+    lines = []
+    open_dates = []
+    for i, day_name in enumerate(DAY_ORDER):
+        date = start_date + timedelta(days=i)
+        date_str = date.strftime("%Y-%m-%d")
+        ext, name, source = schedule.resolve_shift(date_str, day_name)
+        is_today = date_str == today_str
+        lines.append(_format_shift_line(date, ext, name, source, is_today))
+        if source == "available":
+            open_dates.append(date_str)
+
+    blocks = [
+        {
+            "type": "header",
+            "text": {"type": "plain_text", "text": f"After-Hours Schedule — {week_label} to {end_label}"},
+        },
+        {
+            "type": "section",
+            "text": {"type": "mrkdwn", "text": "\n".join(lines)},
+        },
+    ]
+
+    # Add pickup buttons for open shifts
+    if open_dates:
+        blocks.append({"type": "divider"})
+        elements = []
+        for date_str in open_dates:
+            dt = datetime.strptime(date_str, "%Y-%m-%d")
+            elements.append(
+                {
+                    "type": "button",
+                    "text": {"type": "plain_text", "text": f"Pick up {dt.strftime('%a %b %-d')}"},
+                    "action_id": f"pickup_{date_str}",
+                    "style": "primary",
+                }
+            )
+        blocks.append({"type": "actions", "elements": elements[:5]})  # Slack max 5 buttons
+
+    return blocks
+
+
+def build_shift_change_message(
+    user_id: str, date_str: str, action: str, ext: str, name: str
+) -> list[dict]:
+    """Build a channel notification for a shift change."""
+    dt = datetime.strptime(date_str, "%Y-%m-%d")
+    day_label = dt.strftime("%A, %b %-d")
+
+    if action == "picked_up":
+        text = f":white_check_mark: <@{user_id}> picked up the shift for *{day_label}* (Ext {ext})"
+    elif action == "dropped":
+        text = f":warning: <@{user_id}> dropped the shift for *{day_label}* — it's now *Available*"
+    elif action == "swapped":
+        text = f":arrows_counterclockwise: <@{user_id}> swapped into the shift for *{day_label}* (Ext {ext})"
+    else:
+        text = f"Shift updated for *{day_label}*: {name} (Ext {ext})"
+
+    return [{"type": "section", "text": {"type": "mrkdwn", "text": text}}]
+
+
+def build_help_blocks() -> list[dict]:
+    """Build help message blocks."""
+    text = (
+        "*After-Hours Shift Manager*\n\n"
+        "`/oncall` — Show this week's schedule\n"
+        "`/oncall next` — Show next week's schedule\n"
+        "`/oncall pick <date>` — Pick up a shift\n"
+        "`/oncall drop <date>` — Drop your shift (marks it open)\n"
+        "`/oncall swap <date> @person` — Swap your shift with someone\n"
+        "`/oncall register <extension>` — Link your Slack account to your extension\n"
+        "`/oncall roster` — Show all registered employees\n"
+        "`/oncall help` — Show this help message\n\n"
+        "_Dates can be: today, tomorrow, monday, friday, 4/5, 2026-04-05_"
+    )
+    return [{"type": "section", "text": {"type": "mrkdwn", "text": text}}]
+
+
+def build_roster_blocks(roster: list[dict]) -> list[dict]:
+    """Build roster display blocks."""
+    if not roster:
+        return [{"type": "section", "text": {"type": "mrkdwn", "text": "No employees in the roster."}}]
+
+    lines = ["*On-Call Roster*\n"]
+    for emp in sorted(roster, key=lambda x: x["SK"]):
+        slack = f"<@{emp['slack_user_id']}>" if emp.get("slack_user_id") else "_not linked_"
+        lines.append(f"Ext {emp['SK']} — {emp.get('name', 'Unknown')} ({slack})")
+
+    return [{"type": "section", "text": {"type": "mrkdwn", "text": "\n".join(lines)}}]
--- a/src/handler.py
+++ b/src/handler.py
@ -0,0 +1,38 @@
+"""Lambda handler — Slack Bolt app entry point."""
+
+import logging
+import os
+
+import boto3
+from slack_bolt.adapter.aws_lambda import SlackRequestHandler
+
+from src.app import create_app
+
+logger = logging.getLogger()
+logger.setLevel(logging.INFO)
+
+SlackRequestHandler.clear_all_log_handlers()
+logging.basicConfig(format="%(asctime)s %(levelname)s %(name)s: %(message)s", level=logging.INFO)
+
+# Lazy-initialized app singleton
+_slack_handler = None
+
+
+def _get_handler() -> SlackRequestHandler:
+    global _slack_handler
+    if _slack_handler is None:
+        ssm = boto3.client("ssm")
+        bot_token = ssm.get_parameter(
+            Name=os.environ["SLACK_BOT_TOKEN_PARAM"], WithDecryption=True
+        )["Parameter"]["Value"]
+        signing_secret = ssm.get_parameter(
+            Name=os.environ["SLACK_SIGNING_SECRET_PARAM"], WithDecryption=True
+        )["Parameter"]["Value"]
+
+        app = create_app(bot_token, signing_secret)
+        _slack_handler = SlackRequestHandler(app=app)
+    return _slack_handler
+
+
+def handler(event, context):
+    return _get_handler().handle(event, context)
--- a/src/schedule.py
+++ b/src/schedule.py
@ -0,0 +1,115 @@
+"""DynamoDB-backed shift schedule management.
+
+Single-table design:
+  PK=ROSTER   SK=<extension>   — employee roster entry
+  PK=WEEKLY   SK=<DayName>     — default weekly schedule
+  PK=OVERRIDE SK=<YYYY-MM-DD>  — date-specific override (or OPEN)
+  PK=CONFIG   SK=CONFIG         — global settings
+"""
+
+import os
+
+import boto3
+from boto3.dynamodb.conditions import Key
+
+
+FALLBACK_EXTENSION = "100"
+
+
+class ShiftSchedule:
+    def __init__(self, table_name: str | None = None):
+        dynamodb = boto3.resource("dynamodb")
+        self.table = dynamodb.Table(table_name or os.environ["SHIFT_TABLE"])
+
+    # ── Roster ──────────────────────────────────────────────────────────
+
+    def get_roster(self) -> list[dict]:
+        resp = self.table.query(KeyConditionExpression=Key("PK").eq("ROSTER"))
+        return resp["Items"]
+
+    def get_employee_by_extension(self, extension: str) -> dict | None:
+        resp = self.table.get_item(Key={"PK": "ROSTER", "SK": extension})
+        return resp.get("Item")
+
+    def get_employee_by_slack_id(self, slack_user_id: str) -> dict | None:
+        for item in self.get_roster():
+            if item.get("slack_user_id") == slack_user_id:
+                return item
+        return None
+
+    def register_user(self, slack_user_id: str, extension: str) -> dict | None:
+        employee = self.get_employee_by_extension(extension)
+        if not employee:
+            return None
+        self.table.update_item(
+            Key={"PK": "ROSTER", "SK": extension},
+            UpdateExpression="SET slack_user_id = :sid",
+            ExpressionAttributeValues={":sid": slack_user_id},
+        )
+        employee["slack_user_id"] = slack_user_id
+        return employee
+
+    # ── Weekly schedule ─────────────────────────────────────────────────
+
+    def get_weekly_schedule(self) -> dict[str, dict]:
+        resp = self.table.query(KeyConditionExpression=Key("PK").eq("WEEKLY"))
+        return {item["SK"]: item for item in resp["Items"]}
+
+    # ── Overrides ───────────────────────────────────────────────────────
+
+    def get_override(self, date_str: str) -> dict | None:
+        resp = self.table.get_item(Key={"PK": "OVERRIDE", "SK": date_str})
+        return resp.get("Item")
+
+    def set_override(self, date_str: str, extension: str, name: str) -> None:
+        self.table.put_item(
+            Item={
+                "PK": "OVERRIDE",
+                "SK": date_str,
+                "extension": extension,
+                "name": name,
+            }
+        )
+
+    def mark_open(self, date_str: str) -> None:
+        self.table.put_item(
+            Item={
+                "PK": "OVERRIDE",
+                "SK": date_str,
+                "extension": "OPEN",
+                "name": "Open",
+            }
+        )
+
+    def remove_override(self, date_str: str) -> None:
+        self.table.delete_item(Key={"PK": "OVERRIDE", "SK": date_str})
+
+    # ── Resolution ──────────────────────────────────────────────────────
+
+    def resolve_shift(self, date_str: str, day_name: str) -> tuple[str, str, str]:
+        """Return (extension, name, source) for a given date.
+
+        source is one of: 'override', 'available', 'weekly'.
+        'available' means no one is assigned — the fallback extension handles
+        it silently on the 3CX side, but users just see it as open for pickup.
+        """
+        override = self.get_override(date_str)
+        if override:
+            if override["extension"] == "OPEN":
+                return (FALLBACK_EXTENSION, "Available", "available")
+            return (override["extension"], override["name"], "override")
+
+        weekly = self.get_weekly_schedule()
+        if day_name in weekly:
+            item = weekly[day_name]
+            if item["extension"] == FALLBACK_EXTENSION:
+                return (FALLBACK_EXTENSION, "Available", "available")
+            return (item["extension"], item.get("name", "Unknown"), "weekly")
+
+        return (FALLBACK_EXTENSION, "Available", "available")
+
+    # ── Config ──────────────────────────────────────────────────────────
+
+    def get_config(self) -> dict:
+        resp = self.table.get_item(Key={"PK": "CONFIG", "SK": "CONFIG"})
+        return resp.get("Item", {})
--- a/src/weekly_post.py
+++ b/src/weekly_post.py
@ -0,0 +1,49 @@
+"""Lambda handler — posts the weekly on-call schedule to Slack every Monday at 7am ET."""
+
+import logging
+import os
+from datetime import datetime, timedelta
+from zoneinfo import ZoneInfo
+
+import boto3
+from slack_sdk import WebClient
+
+from src.blocks import build_week_schedule
+from src.schedule import ShiftSchedule
+
+logger = logging.getLogger()
+logger.setLevel(logging.INFO)
+
+EASTERN = ZoneInfo("America/New_York")
+
+
+def handler(event, context):
+    now = datetime.now(EASTERN)
+
+    # DST guard — same pattern as the 3CX scheduler
+    if now.hour != 7:
+        logger.info("ET hour is %d, not 7am — skipping (wrong DST rule fired)", now.hour)
+        return {"skipped": True}
+
+    ssm = boto3.client("ssm")
+    bot_token = ssm.get_parameter(
+        Name=os.environ["SLACK_BOT_TOKEN_PARAM"], WithDecryption=True
+    )["Parameter"]["Value"]
+    channel_id = ssm.get_parameter(
+        Name=os.environ["SHIFT_CHANNEL_PARAM"], WithDecryption=True
+    )["Parameter"]["Value"]
+
+    schedule = ShiftSchedule()
+    slack = WebClient(token=bot_token)
+
+    # Show this week (Monday = today)
+    blocks = build_week_schedule(schedule, start_date=now)
+
+    slack.chat_postMessage(
+        channel=channel_id,
+        blocks=blocks,
+        text=f"After-Hours Schedule — Week of {now.strftime('%b %-d')}",
+    )
+
+    logger.info("Posted weekly schedule to channel %s", channel_id)
+    return {"posted": True, "channel": channel_id}
--- a/template.yaml
+++ b/template.yaml
@ -0,0 +1,132 @@
+AWSTemplateFormatVersion: "2010-09-09"
+Transform: AWS::Serverless-2016-10-31
+Description: After-Hours Shift Manager — Slack bot for managing on-call shifts with 3CX integration
+
+Parameters:
+  Timezone:
+    Type: String
+    Default: "America/New_York"
+  SchedulerFunctionName:
+    Type: String
+    Default: "3cx-ring-group-scheduler"
+    Description: Name of the existing 3CX ring group scheduler Lambda
+
+Globals:
+  Function:
+    Runtime: python3.12
+    Timeout: 30
+    MemorySize: 1024
+
+Resources:
+  # --- DynamoDB ---
+  ShiftTable:
+    Type: AWS::DynamoDB::Table
+    Properties:
+      TableName: afterhours-shifts
+      BillingMode: PAY_PER_REQUEST
+      AttributeDefinitions:
+        - AttributeName: PK
+          AttributeType: S
+        - AttributeName: SK
+          AttributeType: S
+      KeySchema:
+        - AttributeName: PK
+          KeyType: HASH
+        - AttributeName: SK
+          KeyType: RANGE
+
+  # --- Slack Bot Lambda ---
+  SlackBotFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      FunctionName: afterhours-shift-manager
+      Handler: src/handler.handler
+      CodeUri: .
+      Environment:
+        Variables:
+          SHIFT_TABLE: !Ref ShiftTable
+          SLACK_BOT_TOKEN_PARAM: /afterhours-shift-manager/slack-bot-token
+          SLACK_SIGNING_SECRET_PARAM: /afterhours-shift-manager/slack-signing-secret
+          SCHEDULER_FUNCTION_NAME: !Ref SchedulerFunctionName
+          TZ: !Ref Timezone
+      Policies:
+        - DynamoDBCrudPolicy:
+            TableName: !Ref ShiftTable
+        - Statement:
+            - Effect: Allow
+              Action:
+                - ssm:GetParameter
+              Resource:
+                - !Sub "arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/afterhours-shift-manager/*"
+            - Effect: Allow
+              Action:
+                - kms:Decrypt
+              Resource: "*"
+              Condition:
+                StringEquals:
+                  "kms:ViaService": !Sub "ssm.${AWS::Region}.amazonaws.com"
+            - Effect: Allow
+              Action:
+                - lambda:InvokeFunction
+              Resource:
+                - !Sub "arn:aws:lambda:${AWS::Region}:${AWS::AccountId}:function:${SchedulerFunctionName}"
+      Events:
+        SlackEvents:
+          Type: HttpApi
+          Properties:
+            Path: /slack/events
+            Method: POST
+
+  # --- Weekly Schedule Post (Monday 7am ET) ---
+  WeeklyPostFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      FunctionName: afterhours-weekly-post
+      Handler: src/weekly_post.handler
+      CodeUri: .
+      Environment:
+        Variables:
+          SHIFT_TABLE: !Ref ShiftTable
+          SLACK_BOT_TOKEN_PARAM: /afterhours-shift-manager/slack-bot-token
+          SHIFT_CHANNEL_PARAM: /afterhours-shift-manager/channel-id
+          TZ: !Ref Timezone
+      Policies:
+        - DynamoDBReadPolicy:
+            TableName: !Ref ShiftTable
+        - Statement:
+            - Effect: Allow
+              Action:
+                - ssm:GetParameter
+              Resource:
+                - !Sub "arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/afterhours-shift-manager/*"
+            - Effect: Allow
+              Action:
+                - kms:Decrypt
+              Resource: "*"
+              Condition:
+                StringEquals:
+                  "kms:ViaService": !Sub "ssm.${AWS::Region}.amazonaws.com"
+      Events:
+        # EST: 7am ET = 12:00 UTC (Nov-Mar)
+        WeeklyPostEST:
+          Type: Schedule
+          Properties:
+            Schedule: cron(0 12 ? * MON *)
+            Description: "Post weekly schedule Monday 7am EST"
+            Enabled: true
+        # EDT: 7am ET = 11:00 UTC (Mar-Nov)
+        WeeklyPostEDT:
+          Type: Schedule
+          Properties:
+            Schedule: cron(0 11 ? * MON *)
+            Description: "Post weekly schedule Monday 7am EDT"
+            Enabled: true
+
+Outputs:
+  SlackBotApiUrl:
+    Description: URL for Slack app Request URL configuration
+    Value: !Sub "https://${ServerlessHttpApi}.execute-api.${AWS::Region}.amazonaws.com/slack/events"
+  ShiftTableName:
+    Value: !Ref ShiftTable
+  SlackBotFunctionArn:
+    Value: !GetAtt SlackBotFunction.Arn