Add Slack bot print endpoint

.agents/skills/printing/SKILL.md

@@ -0,0 +1,315 @@
+# Papercut Print API
+
+Print anything on a physical receipt printer by posting markdown content to a single endpoint.
+
+## Endpoint
+
+```
+POST https://papercut.krabby.dev/webhooks/slack
+Content-Type: application/json
+```
+
+No authentication required.
+
+## Request Body
+
+```json
+{
+  "content": "# Your markdown content here",
+  "include_header": true,
+  "include_footer": true,
+  "footer_url": "https://example.com",
+  "cut": true
+}
+```
+
+| Field | Type | Required | Default | Description |
+|---|---|---|---|---|
+| `content` | string | **Yes** | | Markdown-formatted content to print |
+| `include_header` | boolean | No | `true` | Print the receipt header (logo, company name, address) |
+| `include_footer` | boolean | No | `true` | Print the receipt footer (footer text, optional QR code) |
+| `footer_url` | string | No | `null` | URL to encode as a QR code in the footer. If omitted, no QR code is printed. |
+| `cut` | boolean | No | `true` | Cut the paper after printing |
+
+The only required field is `content`. The simplest possible request:
+
+```json
+{"content": "Hello, world!"}
+```
+
+## Response
+
+```json
+{
+  "status": "printed",
+  "message": "Content sent to printer",
+  "content_length": 123
+}
+```
+
+## Receipt Dimensions
+
+The printer is an 80mm thermal receipt printer. The printable area is:
+
+- **Text width:** 48 characters per line
+- **Image width:** 576 pixels max
+
+All text is automatically word-wrapped to fit within 48 characters. Images must be sized to 576px wide or smaller by the caller.
+
+## Two-Column Layout
+
+To print key-value detail lines (like ticket metadata), use space padding to right-align values. The receipt is exactly **48 characters wide**. Pad each line so the total length is exactly 48 characters:
+
+```
+spaces = 48 - len(label) - len(value)
+line = label + (" " * spaces) + value
+```
+
+Every line must be **exactly 48 characters total**. No more, no less. If a line is shorter, the value won't be right-aligned. If longer, it will wrap and break the layout.
+
+### Example calculation
+
+```
+"ID:"      (3 chars) + "ENG-42"       (6 chars)  = 39 spaces → 48 total
+"Team:"    (5 chars) + "Engineering" (11 chars)  = 32 spaces → 48 total
+"Priority:"(9 chars) + "High"         (4 chars)  = 35 spaces → 48 total
+"Status:"  (7 chars) + "In Progress" (11 chars)  = 30 spaces → 48 total
+```
+
+### Example output on the receipt
+
+```
+ID:                                       ENG-42
+Team:                                Engineering
+Priority:                                   High
+Status:                              In Progress
+```
+
+### Implementation (pseudocode)
+
+```python
+WIDTH = 48
+
+def format_detail(label: str, value: str) -> str:
+    spaces = WIDTH - len(label) - len(value)
+    return label + (" " * spaces) + value
+
+details = [
+    format_detail("ID:", "ENG-42"),
+    format_detail("Team:", "Engineering"),
+    format_detail("Priority:", "High"),
+]
+
+# Join with newlines — each line is exactly 48 chars
+detail_block = "\n".join(details)
+```
+
+## Section Spacing
+
+Use blank lines (`\n\n`) to separate visual sections. Without them, the receipt looks like one dense blob of text.
+
+Required spacing for a well-formatted receipt:
+
+```
+[detail lines — no blank lines between them]
+                                            ← blank line
+# Title
+                                            ← blank line
+Description text, bullets, images, etc.
+```
+
+In the content string, this means:
+
+```
+...last detail line\n\n# Title\n\nDescription starts here...
+```
+
+## Supported Markdown
+
+The `content` field accepts markdown. The following elements are rendered with receipt-appropriate formatting:
+
+### Headers
+
+```markdown
+# H1 - Bold, double width, double height (use for titles)
+## H2 - Bold, double height (use for section identifiers)
+### H3 through H6 - Bold
+```
+
+### Inline Formatting
+
+```markdown
+**bold text** - Prints bold
+*italic text* - Prints underlined (thermal printers have no italic)
+```
+
+### Bullet Lists
+
+```markdown
+- Item one
+- Item two
+* Also works with asterisks
+```
+
+### Inline Images
+
+```markdown
+![alt text](https://example.com/image.png)
+```
+
+Images are downloaded and printed inline within the content flow. They must be:
+- **Max 576px wide** (the printer's printable area)
+- A supported format: PNG, JPG, GIF, or BMP
+- Accessible via a public URL
+
+If an image fails to download or exceeds the max width, a text placeholder is printed instead.
+
+### Plain Text
+
+Anything that isn't a recognized markdown element prints as-is, with automatic word wrapping to 48 characters.
+
+## Ticket Format Reference
+
+To replicate the standard ticket receipt layout (matching the Linear ticket format), structure the content as follows:
+
+### Structure
+
+```
+[two-column details — space-padded to 48 chars each]
+[blank line]
+[# Title as H1]
+[blank line]
+[description — markdown with bullets, bold, etc.]
+```
+
+### Full example payload
+
+```json
+{
+  "content": "ID:                                       ENG-42\nTeam:                                Engineering\nPriority:                                   High\nStatus:                              In Progress\nProject:                             Papercut v2\nAssignee:                               Jane Doe\nCreator:                              John Smith\nLabels:                            bug, frontend\n\n# Fix login page CSS regression\n\nThe login button has a CSS regression causing it to overlap with the password field on mobile viewports under 375px.\n\n- Regression introduced in PR #127\n- Affects Safari and Chrome on iOS\n- **Blocking** v2.1 release",
+  "footer_url": "https://google.com"
+}
+```
+
+### What prints on the receipt
+
+```
+[logo]
+[company header]
+[timestamp]
+
+ID:                                       ENG-42
+Team:                                Engineering
+Priority:                                   High
+Status:                              In Progress
+Project:                             Papercut v2
+Assignee:                               Jane Doe
+Creator:                              John Smith
+Labels:                            bug, frontend
+
+      FIX LOGIN PAGE CSS
+         REGRESSION
+
+The login button has a CSS regression
+causing it to overlap with the password
+field on mobile viewports under 375px.
+
+• Regression introduced in PR #127
+• Affects Safari and Chrome on iOS
+• Blocking v2.1 release
+
+          Scan for details:
+          [QR code → google.com]
+          [footer text]
+```
+
+### Building a ticket programmatically
+
+```python
+WIDTH = 48
+
+def format_detail(label: str, value: str) -> str:
+    spaces = WIDTH - len(label) - len(value)
+    return label + (" " * spaces) + value
+
+def build_ticket(
+    details: list[tuple[str, str]],
+    title: str,
+    description: str,
+) -> str:
+    lines = [format_detail(label, value) for label, value in details]
+    detail_block = "\n".join(lines)
+    return f"{detail_block}\n\n# {title}\n\n{description}"
+
+# Usage
+content = build_ticket(
+    details=[
+        ("ID:", "ENG-42"),
+        ("Team:", "Engineering"),
+        ("Priority:", "High"),
+        ("Status:", "In Progress"),
+        ("Assignee:", "Jane Doe"),
+        ("Labels:", "bug, frontend"),
+    ],
+    title="Fix login page CSS regression",
+    description=(
+        "The login button has a CSS regression.\n\n"
+        "- Regression in PR #127\n"
+        "- Affects Safari and Chrome\n"
+        "- **Blocking** v2.1 release"
+    ),
+)
+```
+
+## Other Examples
+
+### Minimal
+
+```json
+{"content": "Just a line of text"}
+```
+
+### With Inline Image
+
+```json
+{
+  "content": "# Daily Report\n\n![chart](https://example.com/chart.png)\n\n**Summary:** All systems operational.",
+  "include_footer": false
+}
+```
+
+### No Header, No Footer, No Cut
+
+```json
+{
+  "content": "Raw content only.\n\nNo header, no footer, no paper cut.\nUseful for chaining multiple prints.",
+  "include_header": false,
+  "include_footer": false,
+  "cut": false
+}
+```
+
+## Content Limits
+
+Content is truncated at **2000 characters** (configurable server-side). Plan your content within this limit.
+
+## curl Examples
+
+Simple print:
+
+```bash
+curl -X POST https://papercut.krabby.dev/webhooks/slack \
+  -H "Content-Type: application/json" \
+  -d '{"content": "# Hello\n\nThis is a **test** print."}'
+```
+
+Ticket-style print with two-column details and QR code:
+
+```bash
+curl -X POST https://papercut.krabby.dev/webhooks/slack \
+  -H "Content-Type: application/json" \
+  -d '{
+    "content": "ID:                                       ENG-42\nTeam:                                Engineering\nPriority:                                   High\nStatus:                              In Progress\n\n# Fix login page CSS regression\n\nThe login button overlaps the password field on mobile.\n\n- Regression in PR #127\n- **Blocking** v2.1 release",
+    "footer_url": "https://google.com"
+  }'
+```

config.py

@@ -55,6 +55,7 @@ class ProvidersConfig:
     """Providers configuration - dynamically populated by provider modules."""
 
     linear: Optional[object] = None  # Will be LinearProviderConfig from provider module
+    slack: Optional[object] = None  # Will be SlackProviderConfig from provider module
 
 
 @dataclass
@@ -220,6 +221,22 @@ def load_config() -> Config:
             f"Linear provider config error (from {config_file_path}):\n{e}"
         ) from e
 
+    # Slack provider (if available)
+    try:
+        from papercut.platforms.slack import (
+            load_config_from_toml as load_slack_config,
+        )
+
+        providers.slack = load_slack_config(toml_data)
+    except ImportError:
+        # Slack provider not installed/available
+        pass
+    except ValueError as e:
+        # Slack config validation failed
+        raise ValueError(
+            f"Slack provider config error (from {config_file_path}):\n{e}"
+        ) from e
+
     # Create config object
     config = Config(
         printer=printer,
@@ -263,6 +280,15 @@ def load_config() -> Config:
         logger.info(
             f"  max_description_length = {config.providers.linear.max_description_length}"
         )
+    if config.providers.slack:
+        logger.info("[providers.slack]")
+        logger.info(f"  disabled = {config.providers.slack.disabled}")
+        logger.info(
+            f"  auth_token = {'***' if config.providers.slack.auth_token else None}"
+        )
+        logger.info(
+            f"  max_content_length = {config.providers.slack.max_content_length}"
+        )
     logger.info("=" * 60)
 
     return config

papercut-schema.json

@@ -170,6 +170,34 @@
             }
           },
           "additionalProperties": false
+        },
+        "slack": {
+          "type": "object",
+          "description": "Slack bot print integration. Receives pre-formatted content and prints it directly.",
+          "default": {
+            "disabled": false,
+            "auth_token": "",
+            "max_content_length": 2000
+          },
+          "properties": {
+            "disabled": {
+              "type": "boolean",
+              "description": "Set to true to disable Slack print endpoint",
+              "default": false
+            },
+            "auth_token": {
+              "type": "string",
+              "description": "Optional bearer token for authentication. Leave empty to allow unauthenticated requests. When set, requests must include 'Authorization: Bearer <token>' header",
+              "default": ""
+            },
+            "max_content_length": {
+              "type": "integer",
+              "description": "Maximum characters for print content before truncation",
+              "minimum": 1,
+              "default": 2000
+            }
+          },
+          "additionalProperties": false
         }
       },
       "additionalProperties": false