initial: notify-email composite action

Fritzlab-themed CI mail action: HTML (inline styles, dark palette) +
plain-text alternative, relayed via mail.fritzlab.net:25 trusted-CIDR rule.
Auto-injects repo/branch/SHA/workflow/run from github context. Status drives
accent + subject prefix (failure/success/info).

.gitignore

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+__pycache__/
+*.pyc

README.md

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+# action/notify-email
+
+Composite Gitea Action that sends a fritzlab-themed email from a CI workflow.
+Renders an HTML body (with plain-text fallback) styled to match the
+`websites/fritzlab.net/theme.css` palette, and relays via `mail.fritzlab.net:25`
+under the trusted-CIDR rule (no SMTP auth — see `k8s-manager` skill `mail.md`).
+
+Gating is the caller's responsibility (typically `if: failure()`). The action
+always sends when invoked.
+
+## Usage
+
+Minimal failure notification:
+
+```yaml
+- name: notify on failure
+  if: failure()
+  uses: https://code.fritzlab.net/action/notify-email@v1
+  with:
+    status: failure
+    summary: "agent deploy failed"
+```
+
+With richer context:
+
+```yaml
+- name: notify on failure
+  if: failure()
+  uses: https://code.fritzlab.net/action/notify-email@v1
+  with:
+    status: failure
+    subject: "agent deploy failed: ${{ github.sha }}"
+    summary: "Deploy of ${{ github.sha }} to bob@${{ vars.DEPLOY_HOST }} failed"
+    details: |
+      Target host: ${{ vars.DEPLOY_HOST }}
+      Branch: ${{ github.ref_name }}
+    from: agent-ci@fritzlab.net
+```
+
+Success notification (e.g. confirm a base-image rebuild cascaded):
+
+```yaml
+- if: success()
+  uses: https://code.fritzlab.net/action/notify-email@v1
+  with:
+    status: success
+    summary: "base #${{ github.run_number }} cascaded to runner"
+```
+
+## Inputs
+
+| Name | Required | Default | Description |
+|---|---|---|---|
+| `summary` | yes | — | One-line headline rendered at the top of the email body. |
+| `status` | no | `info` | `failure` / `success` / `info` — drives accent colour + subject prefix. |
+| `subject` | no | `summary` | Mail subject after the status prefix. |
+| `details` | no | — | Multiline preformatted block, rendered in a monospace card. |
+| `to` | no | `noc@fritzlab.net` | Recipient address. |
+| `from` | no | `ci@fritzlab.net` | Sender address. Must be permitted by the relay. |
+| `smtp-host` | no | `mail.fritzlab.net` | SMTP relay host. |
+| `smtp-port` | no | `25` | SMTP port. |
+
+## Auto-injected fields
+
+The action reads the following from `${{ github.* }}` and includes them in
+both HTML and text bodies — callers do not need to pass these:
+
+- Repository (linked to Gitea repo page)
+- Branch (`ref_name`)
+- Commit (short SHA linked to commit page)
+- Workflow / job
+- Run number (+ attempt if `> 1`)
+- Trigger (`event_name` by `actor`)
+- "view run" button linking to the Actions run
+
+## Status styling
+
+| Status | Subject prefix | Accent |
+|---|---|---|
+| `failure` | `[FAILED]` | red (`#fca5a5`) |
+| `success` | `[OK]` | green (`#86efac`) |
+| `info` | `[INFO]` | violet (`#7c5cff`) — fritzlab default accent |
+
+## Headers added
+
+- `X-Fritzlab-Status: failure | success | info`
+- `X-Fritzlab-Source: action/notify-email`
+- `X-Fritzlab-Repo: <owner>/<repo>`
+
+These can be used as Sieve filters in Stalwart to route or tag CI mail.
+
+## Why HTML in a CI email
+
+Email clients strip `<style>` blocks and `@import` and cannot fetch web fonts,
+so the fritzlab palette is inlined per-element. Dark-only — fritzlab brand has
+no light variant. The plain-text alternative covers terminal mail readers and
+spam-filter previews.

action.yaml

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+name: Notify by Email
+description: |
+  Send a fritzlab-themed email from a CI workflow via mail.fritzlab.net.
+  Gating is the caller's responsibility (typically `if: failure()`); the
+  action always sends when invoked. Auto-injects repo, branch, SHA, workflow,
+  and run URL — caller supplies subject, summary, and optional details.
+inputs:
+  to:
+    description: Recipient address.
+    required: false
+    default: noc@fritzlab.net
+  from:
+    description: Sender address. Must be permitted by mail.fritzlab.net relay rules.
+    required: false
+    default: ci@fritzlab.net
+  status:
+    description: failure | success | info — drives accent color and subject prefix.
+    required: false
+    default: info
+  subject:
+    description: Mail subject (status prefix is added automatically). Defaults to summary when empty.
+    required: false
+    default: ''
+  summary:
+    description: One-line headline rendered at the top of the email body.
+    required: true
+  details:
+    description: Optional multiline preformatted block (rendered in a monospace card). Leave empty to omit.
+    required: false
+    default: ''
+  smtp-host:
+    description: SMTP relay host.
+    required: false
+    default: mail.fritzlab.net
+  smtp-port:
+    description: SMTP port (relay is on 25, trusted-CIDR, no auth).
+    required: false
+    default: '25'
+runs:
+  using: composite
+  steps:
+    - name: Send notification
+      shell: bash
+      env:
+        NOTIFY_TO: ${{ inputs.to }}
+        NOTIFY_FROM: ${{ inputs.from }}
+        NOTIFY_STATUS: ${{ inputs.status }}
+        NOTIFY_SUBJECT: ${{ inputs.subject }}
+        NOTIFY_SUMMARY: ${{ inputs.summary }}
+        NOTIFY_DETAILS: ${{ inputs.details }}
+        NOTIFY_SMTP_HOST: ${{ inputs.smtp-host }}
+        NOTIFY_SMTP_PORT: ${{ inputs.smtp-port }}
+        GH_SERVER_URL: ${{ github.server_url }}
+        GH_REPOSITORY: ${{ github.repository }}
+        GH_REF_NAME: ${{ github.ref_name }}
+        GH_SHA: ${{ github.sha }}
+        GH_WORKFLOW: ${{ github.workflow }}
+        GH_JOB: ${{ github.job }}
+        GH_RUN_ID: ${{ github.run_id }}
+        GH_RUN_NUMBER: ${{ github.run_number }}
+        GH_RUN_ATTEMPT: ${{ github.run_attempt }}
+        GH_ACTOR: ${{ github.actor }}
+        GH_EVENT_NAME: ${{ github.event_name }}
+      run: python3 ${{ github.action_path }}/scripts/send.py

scripts/send.py

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+#!/usr/bin/env python3
+"""Build and send a fritzlab-themed CI notification email.
+
+Reads inputs from environment variables (set by action.yaml). Delivers a
+multipart/alternative message (plain text + inline-styled HTML) over plain SMTP
+to mail.fritzlab.net, which relays via trusted-CIDR rules (see mail.md).
+"""
+from __future__ import annotations
+
+import os
+import smtplib
+import sys
+from email.message import EmailMessage
+from html import escape
+from typing import Iterable
+
+# fritzlab tokens (mirror websites/fritzlab.net/theme.css). Inlined here because
+# email clients strip <style>, drop @import, and cannot fetch web fonts.
+CANVAS = "#0a0a0a"
+SURFACE = "#111113"
+BORDER = "#1f1f23"
+BORDER_STRONG = "#2a2a2e"
+TEXT = "#ededed"
+MUTED = "#888888"
+MUTED_STRONG = "#a8a8a8"
+
+ACCENT_VIOLET = "#7c5cff"
+ERROR_FG = "#fca5a5"
+ERROR_BG = "#2a0f0f"
+ERROR_BORDER = "#4a1818"
+OK_FG = "#86efac"  # not in theme.css; added for HTML email status pills
+OK_BORDER = "#1f3a2a"
+OK_BG = "#0f1f15"
+
+FONT_SANS = (
+    "'Geist', -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', "
+    "Helvetica, Arial, sans-serif"
+)
+FONT_MONO = "'Geist Mono', ui-monospace, 'JetBrains Mono', Menlo, monospace"
+
+
+def status_palette(status: str) -> dict[str, str]:
+    """Return colour + label tokens for a given status string."""
+    s = (status or "info").strip().lower()
+    if s == "failure":
+        return {
+            "key": "failure",
+            "label": "FAILED",
+            "fg": ERROR_FG,
+            "bg": ERROR_BG,
+            "border": ERROR_BORDER,
+            "subject_prefix": "[FAILED]",
+        }
+    if s == "success":
+        return {
+            "key": "success",
+            "label": "OK",
+            "fg": OK_FG,
+            "bg": OK_BG,
+            "border": OK_BORDER,
+            "subject_prefix": "[OK]",
+        }
+    return {
+        "key": "info",
+        "label": "INFO",
+        "fg": ACCENT_VIOLET,
+        "bg": "rgba(124, 92, 255, 0.08)",
+        "border": "#2a2050",
+        "subject_prefix": "[INFO]",
+    }
+
+
+def required(name: str) -> str:
+    v = os.environ.get(name, "").strip()
+    if not v:
+        print(f"FATAL: required env var {name} is empty", file=sys.stderr)
+        sys.exit(1)
+    return v
+
+
+def fact_rows(items: Iterable[tuple[str, str, str]]) -> tuple[str, str]:
+    """Build the HTML <table> rows and plain-text lines for the fact list.
+
+    Each item is (label, text_value, html_value). Items whose text_value is
+    empty are skipped — the HTML/text outputs stay in lockstep.
+    """
+    html_rows: list[str] = []
+    text_lines: list[str] = []
+    for label, text_value, html_value in items:
+        if not text_value:
+            continue
+        html_rows.append(
+            f'<tr>'
+            f'<td style="color:{MUTED};font-family:{FONT_MONO};font-size:12px;'
+            f'padding:4px 24px 4px 0;vertical-align:top;white-space:nowrap;'
+            f'text-transform:uppercase;letter-spacing:0.12em;">{escape(label)}</td>'
+            f'<td style="color:{TEXT};font-family:{FONT_SANS};font-size:14px;'
+            f'padding:4px 0;line-height:1.5;">{html_value}</td>'
+            f'</tr>'
+        )
+        text_lines.append(f"{label:<11} {text_value}")
+    return "\n".join(html_rows), "\n".join(text_lines)
+
+
+def render(
+    *,
+    palette: dict[str, str],
+    summary: str,
+    details: str,
+    facts: list[tuple[str, str]],
+    run_url: str,
+) -> tuple[str, str]:
+    """Return (html, text) bodies."""
+    rows_html, rows_text = fact_rows(facts)
+
+    pill = (
+        f'<span style="display:inline-block;font-family:{FONT_MONO};'
+        f'font-size:11px;font-weight:600;letter-spacing:0.14em;'
+        f'padding:4px 10px;border-radius:6px;'
+        f'color:{palette["fg"]};background:{palette["bg"]};'
+        f'border:1px solid {palette["border"]};text-transform:uppercase;">'
+        f'{palette["label"]}</span>'
+    )
+
+    details_block_html = ""
+    if details.strip():
+        details_block_html = f"""
+        <tr><td style="padding:8px 32px 0 32px;">
+          <div style="font-family:{FONT_MONO};font-size:11px;color:{MUTED};
+                      text-transform:uppercase;letter-spacing:0.14em;
+                      margin:18px 0 8px 0;">details</div>
+          <pre style="margin:0;padding:14px 16px;background:{CANVAS};
+                      border:1px solid {BORDER};border-radius:8px;
+                      color:{MUTED_STRONG};font-family:{FONT_MONO};
+                      font-size:12px;line-height:1.55;white-space:pre-wrap;
+                      word-break:break-word;overflow-x:auto;">{escape(details)}</pre>
+        </td></tr>
+        """
+
+    html = f"""<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="color-scheme" content="dark">
+  <meta name="supported-color-schemes" content="dark">
+  <title>{escape(summary)}</title>
+</head>
+<body style="margin:0;padding:0;background:{CANVAS};color:{TEXT};
+             font-family:{FONT_SANS};-webkit-font-smoothing:antialiased;">
+  <table role="presentation" width="100%" cellpadding="0" cellspacing="0"
+         border="0" style="background:{CANVAS};padding:32px 16px;">
+    <tr><td align="center">
+      <table role="presentation" width="600" cellpadding="0" cellspacing="0"
+             border="0" style="max-width:600px;width:100%;background:{SURFACE};
+                               border:1px solid {BORDER};border-radius:12px;
+                               overflow:hidden;">
+        <tr><td style="padding:28px 32px 8px 32px;">
+          {pill}
+          <h1 style="margin:14px 0 0 0;font-family:{FONT_SANS};font-size:20px;
+                     font-weight:600;letter-spacing:-0.015em;color:{TEXT};
+                     line-height:1.35;">{escape(summary)}</h1>
+        </td></tr>
+        <tr><td style="padding:20px 32px 8px 32px;">
+          <hr style="border:0;border-top:1px solid {BORDER};margin:0 0 16px 0;">
+          <table role="presentation" cellpadding="0" cellspacing="0" border="0"
+                 style="width:100%;">
+            {rows_html}
+          </table>
+        </td></tr>
+        {details_block_html}
+        <tr><td style="padding:24px 32px 28px 32px;">
+          <a href="{escape(run_url)}"
+             style="display:inline-block;font-family:{FONT_SANS};font-size:14px;
+                    font-weight:500;color:{TEXT};text-decoration:none;
+                    padding:11px 22px;border:1px solid {BORDER_STRONG};
+                    border-radius:8px;background:transparent;">
+            view run <span style="color:{palette['fg']};">&rarr;</span>
+          </a>
+        </td></tr>
+        <tr><td style="padding:0 32px 24px 32px;">
+          <div style="font-family:{FONT_MONO};font-size:11px;color:{MUTED};
+                      border-top:1px solid {BORDER};padding-top:14px;
+                      letter-spacing:0.02em;">
+            sent by <span style="color:{MUTED_STRONG};">action/notify-email</span>
+            &middot; mail.fritzlab.net
+          </div>
+        </td></tr>
+      </table>
+    </td></tr>
+  </table>
+</body>
+</html>
+"""
+
+    text = (
+        f"[{palette['label']}] {summary}\n"
+        f"{'-' * 64}\n"
+        f"{rows_text}\n"
+    )
+    if details.strip():
+        text += f"\nDetails:\n{details.rstrip()}\n"
+    text += f"\nRun: {run_url}\n"
+    return html, text
+
+
+def main() -> int:
+    summary = required("NOTIFY_SUMMARY")
+    to_addr = required("NOTIFY_TO")
+    from_addr = required("NOTIFY_FROM")
+    smtp_host = required("NOTIFY_SMTP_HOST")
+    smtp_port = int(required("NOTIFY_SMTP_PORT"))
+    subject_in = os.environ.get("NOTIFY_SUBJECT", "").strip()
+    details = os.environ.get("NOTIFY_DETAILS", "")
+
+    palette = status_palette(os.environ.get("NOTIFY_STATUS", "info"))
+
+    server_url = os.environ.get("GH_SERVER_URL", "").rstrip("/")
+    repo = os.environ.get("GH_REPOSITORY", "")
+    sha = os.environ.get("GH_SHA", "")
+    short_sha = sha[:8] if sha else ""
+    run_id = os.environ.get("GH_RUN_ID", "")
+    run_url = f"{server_url}/{repo}/actions/runs/{run_id}" if server_url and repo and run_id else ""
+
+    commit_html = ""
+    if sha:
+        if server_url and repo:
+            commit_html = (
+                f'<a href="{escape(server_url)}/{escape(repo)}/commit/{escape(sha)}" '
+                f'style="color:{TEXT};text-decoration:none;'
+                f'border-bottom:1px dotted {MUTED};font-family:{FONT_MONO};'
+                f'font-size:12px;">{escape(short_sha)}</a>'
+            )
+        else:
+            commit_html = f'<span style="font-family:{FONT_MONO};font-size:12px;">{escape(short_sha)}</span>'
+
+    repo_html = ""
+    if repo:
+        if server_url:
+            repo_html = (
+                f'<a href="{escape(server_url)}/{escape(repo)}" '
+                f'style="color:{TEXT};text-decoration:none;'
+                f'border-bottom:1px dotted {MUTED};">{escape(repo)}</a>'
+            )
+        else:
+            repo_html = escape(repo)
+
+    ref_name = os.environ.get("GH_REF_NAME", "")
+    workflow = os.environ.get("GH_WORKFLOW", "")
+    job = os.environ.get("GH_JOB", "")
+    run_number = os.environ.get("GH_RUN_NUMBER", "")
+    run_attempt = os.environ.get("GH_RUN_ATTEMPT", "")
+    actor = os.environ.get("GH_ACTOR", "")
+    event_name = os.environ.get("GH_EVENT_NAME", "")
+
+    # Workflow line: include job only if it differs from the workflow name
+    # (composite-action runs often have workflow == job, e.g. "deploy / deploy").
+    if workflow and job and job != workflow:
+        workflow_text = f"{workflow} / {job}"
+        workflow_html = f"{escape(workflow)} <span style=\"color:{MUTED};\">/</span> {escape(job)}"
+    elif workflow:
+        workflow_text = workflow
+        workflow_html = escape(workflow)
+    else:
+        workflow_text = workflow_html = ""
+
+    run_text = ""
+    run_html = ""
+    if run_number:
+        run_text = f"#{run_number}"
+        run_html = f"#{escape(run_number)}"
+        if run_attempt and run_attempt != "1":
+            run_text += f" (attempt {run_attempt})"
+            run_html += f" (attempt {escape(run_attempt)})"
+
+    trigger_text = ""
+    trigger_html = ""
+    if event_name:
+        trigger_text = event_name + (f" by {actor}" if actor else "")
+        trigger_html = escape(event_name) + (f" by {escape(actor)}" if actor else "")
+
+    facts: list[tuple[str, str, str]] = [
+        ("Repository", repo, repo_html),
+        ("Branch", ref_name, escape(ref_name) if ref_name else ""),
+        ("Commit", short_sha, commit_html),
+        ("Workflow", workflow_text, workflow_html),
+        ("Run", run_text, run_html),
+        ("Trigger", trigger_text, trigger_html),
+    ]
+
+    html, text = render(
+        palette=palette,
+        summary=summary,
+        details=details,
+        facts=facts,
+        run_url=run_url,
+    )
+
+    msg = EmailMessage()
+    subject_body = subject_in or summary
+    msg["Subject"] = f"{palette['subject_prefix']} {subject_body}"
+    msg["From"] = from_addr
+    msg["To"] = to_addr
+    msg["X-Fritzlab-Status"] = palette["key"]
+    msg["X-Fritzlab-Source"] = "action/notify-email"
+    if repo:
+        msg["X-Fritzlab-Repo"] = repo
+    msg.set_content(text)
+    msg.add_alternative(html, subtype="html")
+
+    print(f"notify-email: sending {palette['key']} to {to_addr} via {smtp_host}:{smtp_port}", file=sys.stderr)
+    with smtplib.SMTP(smtp_host, smtp_port, timeout=15) as s:
+        s.send_message(msg)
+    print("notify-email: sent", file=sys.stderr)
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())