feat: activate 106 visual-validated canaries via swap

Imports 105 MD files (plus quick-start already present) from
origin/myst/current and adds them to docs/_swap.txt. The selection
is the BackstopJS visual-passers cohort: pages with <5% rendered
diff vs the live RST docs at docs.vyos.io/en/latest/, filtered to
those with an RST counterpart on current and no cmdincludemd usage
(template-format reconciliation pending).

Local sphinx-build with all 106 swapped: succeeded with 100
warnings (vs 95 baseline). The 5 new warnings are all undefined
cross-reference labels, not build failures:
- contributing/development.md (missing 'coding-guidelines')
- operation/upgrade-recovery.md (3 missing 'how_it_works' /
  'cancelling_recovery')
- vpp/configuration/dataplane/{buffers,memory,unix}.md (missing
  'vpp_config_dataplane_*' labels)

Source list: ~/.claude/projects/-Users-vybot-GitHub-vyos-documentation/docs/2026-04-29-myst-conversion-audit/visual-passers-under-5pct.txt
BackstopJS report: claude/gifted-hertz-74b9f9 worktree
(visual-compare/), 2026-04-23 vs vyos--1838.org.readthedocs.build.

🤖 Generated by [robots](https://vyos.io)

1 files changed, 541 insertions, 0 deletions

diff --git a/docs/contributing/md-development.md b/docs/contributing/md-development.md
new file mode 100644
index 00000000..8581a28e
--- /dev/null
+++ b/docs/contributing/md-development.md
@@ -0,0 +1,541 @@
+---
+lastproofread: '2025-12-12'
+---
+
+(development)=
+
+# Development
+
+Learn how to contribute to VyOS.
+
+(architecture-overview)=
+
+## Architecture overview
+
+VyOS source code is hosted on GitHub in the VyOS organization:
+<https://github.com/vyos>
+
+VyOS is composed of multiple modules spread across different
+repositories. Some modules contain forks of upstream
+packages and are periodically synced.
+VyOS consolidates most packages into the
+[vyos-1x](https://github.com/vyos/vyos-1x)
+repository while maintaining a consistent structure.
+The base code is being rewritten
+from Perl and Bash to Python using an XML-based CLI interface definition.
+
+VyOS ISO build scripts are hosted in the
+[vyos-build](https://github.com/vyos/vyos-build) repository. See the
+`vyos-build` repository
+[README.md file](https://github.com/vyos/vyos-build/blob/current/README.md)
+for more information on building VyOS ISO images.
+
+## Contributing code
+
+:::{warning}
+You must sign the {doc}`Contributor License Agreement<cla>`
+for your contributions to be accepted.
+:::
+
+VyOS is open-source and welcomes patches.
+All submissions must adhere to these guidelines:
+
+- Each commit addresses a single issue or feature.
+- Each commit message references a [Phabricator](https://vyos.dev/) task ID
+  (for example, `T1234`).
+- Each commit is associated with a username and email address
+  to identify the author (see [Configure your Git identity](configure-your-git-identity)).
+- Only submit bugfixes in packages other than <https://github.com/vyos/vyos-1x>.
+- Commits follow the [coding guidelines](coding-guidelines) outlined below.
+
+### Determining package ownership
+
+To determine which VyOS package contains a file you want to modify, use Debian's
+`dpkg -S` command on your running VyOS installation.
+
+### Submitting your code
+
+Fork the repository and submit a GitHub pull request. This is the preferred way
+to contribute changes to VyOS.
+
+To fork a VyOS repository:
+
+1. Append `/fork` to the repository URL on GitHub. For example, to fork
+   `vyos-1x`, use: <https://github.com/vyos/vyos-1x/fork>
+
+2. Clone your fork or add it as a remote to your local repository:
+
+   - Clone: `git clone https://github.com/<user>/vyos-1x.git`
+   - Add remote: `git remote add myfork https://github.com/<user>/vyos-1x.git`
+
+(configure-your-git-identity)=
+
+3. Configure your Git identity:
+
+   ```none
+   git config --global user.name "J. Random Hacker"
+   git config --global user.email "jrhacker@example.net"
+   ```
+
+4. Make your changes and add files to the Git index:
+
+   - Single file: `git add myfile`
+   - Directory: `git add somedir/*`
+
+5. Commit your changes with a meaningful headline and [Phabricator](https://vyos.dev/) reference:
+
+   `git commit`
+
+6. Push to your fork and create a GitHub pull request:
+
+   `git push`
+
+Alternatively, you can export commits as patches and send them to
+<mailto:maintainers@vyos.net> or attach them directly to the [Phabricator](https://vyos.dev/) task:
+
+- Export last commit: `git format-patch`
+- Export last two commits: `git format-patch -2`
+
+## Commit messages
+
+For guidance on writing commit messages, review the file history
+with `git log path/to/file.txt`.
+
+Every change must be associated with a task number (prefixed with **T**) and
+a component. If no bug report or feature request exists for your changes,
+create a [Phabricator](https://vyos.dev/) task first. Reference the task ID in your commit message:
+
+- `ddclient: T1030: auto create runtime directories`
+- `Jenkins: add current Git commit ID to build description`
+
+If your pull request lacks a [Phabricator](https://vyos.dev/) reference, maintainers will request
+that you amend the commit message.
+
+### Writing good commit messages
+
+Follow the format described in
+the [Git documentation](https://git-scm.com/book/ch5-2.html)
+and [Chris Beams' guide](https://chris.beams.io/posts/git-commit/).
+
+Commit message format:
+
+1. **Summary line** (50 characters recommended, 80 maximum): Include the
+   component
+   prefix and [Phabricator](https://vyos.dev/) reference (for example, `snmp: T1111:` or
+   `ethernet: T2222:`). Concatenate multiple components with colons
+   (for example, `snmp: ethernet: T3333`).
+2. **Blank line**: Separate the summary from the body.
+   This blank line is critical.
+
+4) **Message body** with details:
+
+   - Describe what changed, why, and how. This helps with `git bisect`.
+   - Wrap text at 72 characters for readability with `git log` on an 80x25
+     terminal.
+   - Reference previous commits when applicable:
+     `After commit abcd12ef ("snmp: this is a headline")
+     a Python import statement is missing, throwing the following exception:
+     ABCDEF`
+
+5) **Cherry-pick option**: Always use the `-x` option when back-porting or
+   forward-porting commits:
+
+   `git cherry-pick -x <commit>`
+
+   This appends `(cherry picked from commit <ID>)` to the commit message,
+   making bisecting easier.
+
+6) **Single responsibility**: Each commit must be self-contained. Do not fix
+   multiple bugs in a single commit. Use `git add --patch` to stage only
+   the parts related to one issue.
+
+Constraints:
+
+- Bugfixes are only accepted for packages other than
+  <https://github.com/vyos/vyos-1x>.
+  New functionality must use the new XML/Python interface, not old-style
+  templates (`node.def` files and Perl/Bash code).
+
+## Coding guidelines
+
+VyOS maintains consistent coding standards to help contributors navigate the
+codebase and understand its logic.
+
+### Formatting
+
+- **Python**: Use 4 spaces per indentation level. Tabs **must not** be used.
+- **XML**: Use 2 spaces per indentation level. Tabs **must not** be used.
+
+Use tools like VIM extensions (xmllint) to enforce correct indentation. Add this
+to your `.vimrc` file:
+```none
+au FileType xml setlocal equalprg=xmllint\ --format\ --recover\ -\ 2>/dev/null
+```
+Then use `gg=G` in command mode to run the linter.
+
+### Text generation
+
+Use a template processor for generating config files:
+
+- **Jinja2** is the default template processor for VyOS code.
+- Built-in string formatting **may** be used for simple line-oriented formats
+  (for example, iptables rules) where every line is self-contained.
+- Template processors **must** be used for structured, multi-line formats
+  (for example, ISC DHCPd configuration).
+
+### Python code
+
+Configuration scripts and operation mode scripts written in Python3 should
+follow these guidelines:
+
+- Wrap lines at 80 characters. This improves readability when browsing
+  GitHub on mobile devices and reads well in side-by-side diffs.
+
+Structure your scripts with these functions:
+```python
+#!/usr/bin/env python3
+#
+# Copyright (C) 2020 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import sys
+
+from vyos.config import Config
+from vyos import ConfigError
+
+def get_config(config=None):
+    if config:
+        conf = config
+    else:
+        conf = Config()
+
+    # Base path to CLI nodes
+    base = ['...', '...']
+    # Convert the VyOS config to an abstract internal representation
+    config_data = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True)
+    return config_data
+
+def verify(config):
+    # Verify that configuration is valid
+    if invalid:
+        raise ConfigError("Descriptive message")
+
+def generate(config):
+    # Generate daemon configs
+    pass
+
+def apply(config):
+    # Apply the generated configs to the live system
+    pass
+
+try:
+    c = get_config()
+    verify(c)
+    generate(c)
+    apply(c)
+except ConfigError as e:
+    print(e)
+    sys.exit(1)
+```
+`get_config()`: This function converts a VyOS config object to an abstract
+internal representation. No other function may call the `vyos.config.Config`
+object directly. Limiting config reads to one function makes it easier to
+modify the config syntax in the future. Additionally, this design improves
+testability since you can construct an internal representation by hand rather
+than mocking the entire config subsystem.
+
+`verify()`: This function validates the internal representation. It must
+raise `ConfigError` with a descriptive message if the config is invalid. It
+**must not** make any changes to the system. This design enables future features
+like commit dry-run ("commit test" as in JunOS) where the system can abort a
+commit before making changes.
+
+`generate()`: This function generates config files for system components.
+
+`apply()`: This function applies the generated configuration to the live
+system. Prefer non-disruptive reload when possible. Disruptive operations like
+daemon restarts are acceptable only when:
+
+- The component does not support non-disruptive reload, or
+- The expected service degradation is minimal (for example, auxiliary services
+  like LLDPd)
+
+For high-impact services (VPN daemons, routing protocols), make effort to
+determine if changes can be applied non-disruptively before resorting to
+restarts.
+
+Never modify active configuration directly unless absolutely necessary. Instead,
+generate configuration files and apply them with a single command like service
+reload through systemd. For example, save iptables rules to a file and load them
+with `iptables-restore` rather than executing iptables commands one by one.
+
+The `apply()` and `generate()` functions may raise `ConfigError` if the
+daemon fails to start with the updated config. However, this is not a substitute
+for proper config validation in the `verify()` function. Make reasonable
+effort to verify that generated configuration is valid and will be accepted by
+the daemon, including cross-checks with other VyOS configuration subtrees when
+necessary.
+
+Exceptions like `VyOSError` (raised by `vyos.config.Config` on improper
+operations) should not be silenced or caught. While this may produce less
+polished error output for users, it generates better bug reports and helps
+maintainers debug issues.
+
+For reference implementations, see `ntp.py` or `interfaces-bonding.py` (for
+tag nodes) in the [vyos-1x](https://github.com/vyos/vyos-1x) repository.
+
+### Other considerations: `vyos-configd`
+
+All scripts now run under the config daemon and must conform to these
+requirements:
+
+1. The signature and first four lines of `get_config(...)` **must** be as
+   specified above.
+2. Each of `get_config`, `verify`, `apply`, and `generate` **must**
+   appear
+   with the correct signatures, even if they are a no-op.
+3. `Config` objects other than those in `get_config` **must not** appear.
+4. The legacy function `my_set` **must not** appear. Modifications to active
+   config **should not** appear in new code (alternative mechanisms may be used
+   if absolutely necessary).
+
+## XML for CLI definitions
+
+XML interface definitions define the VyOS CLI structure.
+Before VyOS `1.2` (crux), these
+files were created manually. After a redesign, new-style templates are
+automatically generated from XML input files.
+
+VyOS interface definitions come with a RelaxNG schema located in the
+[vyos-1x](https://github.com/vyos/vyos-1x/tree/current/schema)
+repository. This schema is a modified version from `VyConf` (VyOS `2.0`).
+VyOS `1.2.x`
+interface definitions are reusable in future VyOS versions with minimal changes.
+
+Schemas provide two benefits:
+
+- Complete grammar verification
+- Automatic validation against the schema
+
+The [build-command-templates](https://github.com/vyos/vyos-1x/blob/current/scripts/build-command-templates)
+script converts XML definitions to
+old-style templates and verifies them against the schema. A bad definition
+causes the package build to fail. While the XML format is verbose, no other
+format provides this level of verification. Specialized XML editors can help
+manage verbosity.
+
+Example XML interface definition:
+```xml
+<?xml version="1.0"?>
+<!-- Cron configuration -->
+<interfaceDefinition>
+  <node name="system">
+    <children>
+      <node name="task-scheduler">
+        <properties>
+          <help>Task scheduler settings</help>
+        </properties>
+        <children>
+          <tagNode name="task" owner="${vyos_conf_scripts_dir}/task_scheduler.py">
+            <properties>
+              <help>Scheduled task</help>
+              <valueHelp>
+                <format>&lt;string&gt;</format>
+                <description>Task name</description>
+              </valueHelp>
+              <priority>999</priority>
+            </properties>
+            <children>
+              <leafNode name="crontab-spec">
+                <properties>
+                  <help>UNIX crontab time specification string</help>
+                </properties>
+              </leafNode>
+              <leafNode name="interval">
+                <properties>
+                  <help>Execution interval</help>
+                  <valueHelp>
+                    <format>&lt;minutes&gt;</format>
+                    <description>Execution interval in minutes</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>&lt;minutes&gt;m</format>
+                    <description>Execution interval in minutes</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>&lt;hours&gt;h</format>
+                    <description>Execution interval in hours</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>&lt;days&gt;d</format>
+                    <description>Execution interval in days</description>
+                  </valueHelp>
+                  <constraint>
+                    <regex>[1-9]([0-9]*)([mhd]{0,1})</regex>
+                  </constraint>
+                </properties>
+              </leafNode>
+              <node name="executable">
+                <properties>
+                  <help>Executable path and arguments</help>
+                </properties>
+                <children>
+                  <leafNode name="path">
+                    <properties>
+                      <help>Path to executable</help>
+                    </properties>
+                  </leafNode>
+                  <leafNode name="arguments">
+                    <properties>
+                      <help>Arguments passed to the executable</help>
+                    </properties>
+                  </leafNode>
+                </children>
+              </node>
+            </children>
+          </tagNode>
+        </children>
+      </node>
+    </children>
+  </node>
+</interfaceDefinition>
+```
+XML definitions are purely declarative and contain no logic. All logic for
+generating config files, restarting services, and related tasks is implemented
+in configuration scripts.
+
+### Template Processors
+
+XML interface definition files use the `.xml.in` file extension (implemented
+in {vytask}`T1843`). These files use the GCC preprocessor to reduce code
+duplication in common areas:
+
+- VIF (including VIF-S and VIF-C)
+- Address configuration
+- Description
+- Enabled/Disabled state
+
+Instead of repeating XML nodes, use include files with predefined features:
+
+- [IPv4, IPv6, and DHCP(v6)](https://github.com/vyos/vyos-1x/blob/current/interface-definitions/include/interface/address-ipv4-ipv6-dhcp.xml.i)
+  address assignment.
+- [IPv4 and IPv6](https://github.com/vyos/vyos-1x/blob/current/interface-definitions/include/interface/address-ipv4-ipv6.xml.i)
+  address assignment.
+- [VLAN (VIF)](https://github.com/vyos/vyos-1x/blob/current/interface-definitions/include/accel-ppp/vlan.xml.i)
+  definition.
+- [MAC address](https://github.com/vyos/vyos-1x/blob/current/interface-definitions/include/firewall/mac-address.xml.i)
+  assignment.
+
+The `.in` files are preprocessed and stored in the [interface-definitions](https://github.com/vyos/vyos-1x/tree/current/interface-definitions)
+folder. The [scripts/build-command-templates](https://github.com/vyos/vyos-1x/blob/current/scripts/build-command-templates)
+script then operates on this folder to generate all required CLI nodes.
+
+Example preprocessor output:
+```none
+$ make interface_definitions
+install -d -m 0755 build/interface-definitions
+install -d -m 0755 build/op-mode-definitions
+Generating build/interface-definitions/intel_qat.xml from interface-definitions/intel_qat.xml.in
+Generating build/interface-definitions/interfaces-bonding.xml from interface-definitions/interfaces-bonding.xml.in
+Generating build/interface-definitions/cron.xml from interface-definitions/cron.xml.in
+Generating build/interface-definitions/pppoe-server.xml from interface-definitions/pppoe-server.xml.in
+Generating build/interface-definitions/mdns-repeater.xml from interface-definitions/mdns-repeater.xml.in
+Generating build/interface-definitions/tftp-server.xml from interface-definitions/tftp-server.xml.in
+[...]
+```
+
+### Command Definition Guidelines
+
+#### Use of Numbers
+
+Avoid using numbers in command names unless the number is part of a protocol
+name or similar. For example, `protocols ospfv3` is appropriate,
+but `server-1` is questionable.
+
+#### Help Strings
+
+Follow these guidelines for consistent, readable help strings:
+
+##### Capitalization and Punctuation
+
+- Capitalize the first word of every help string.
+- Do not use a period at the end of help strings.
+
+This standard mirrors network device CLIs and improves aesthetics.
+
+Examples:
+
+- Good: "Frobnication algorithm"
+- Bad: "frobnication algorithm"
+- Bad: "Frobnication algorithm."
+- Incorrect: "frobnication algorithm."
+
+##### Abbreviations and Acronyms
+
+- Capitalize all abbreviations and acronyms.
+
+Examples:
+
+- Good: "TCP connection timeout"
+- Bad: "tcp connection timeout"
+- Bad: "Tcp connection timeout"
+- Capitalize acronyms to distinguish them from normal words.
+
+Examples:
+
+- Good: RADIUS (remote authentication for dial-in user services)
+- Bad: radius (unless referring to circular distance)
+- Follow accepted spelling conventions for mixed-case abbreviations. If it
+  contains "over" or "version", use lowercase. Follow RFC or standard spellings
+  when they exist.
+
+Examples:
+
+- Good: PPPoE, IPsec
+- Bad: PPPOE, IPSEC
+- Bad: pppoe, ipsec
+
+##### Verbs
+
+- Avoid verbs. If a verb can be omitted, omit it.
+
+Examples:
+
+- Good: "TCP connection timeout"
+- Bad: "Set TCP connection timeout"
+- When a verb is essential, use it. For example: "Disable IPv6 forwarding on
+  all interfaces" for `set system ipv6 disable-forwarding`.
+- Use infinitive form for necessary verbs.
+
+Examples:
+
+- Good: "Disable IPv6 forwarding"
+- Bad: "Disables IPv6 forwarding"
+
+## C++ Backend Code
+
+The VyOS CLI parser combines bash, bash-completion helpers, and the C++ backend
+library [vyatta-cfg](https://github.com/vyos/vyatta-cfg). This section
+references common CLI commands and their C/C++ entry points:
+
+`set`:
+
+- <https://github.com/vyos/vyatta-cfg/blob/0f42786a0b3/src/cstore/cstore.cpp#L352>
+- <https://github.com/vyos/vyatta-cfg/blob/0f42786a0b3/src/cstore/cstore.cpp#L2549>
+
+`commit`:
+
+- <https://github.com/vyos/vyatta-cfg/blob/0f42786a0b3/src/commit/commit-algorithm.cpp#L1252>
+
+