Add incremental RST-to-MyST swap mechanism (#1857)

* feat: add swap_sources.py for incremental RST-to-MyST migration

Pre-build swap/restore script that renames md-{name}.md → {name}.md
before Sphinx builds and restores after. Includes state tracking,
exclude file generation, collision detection, and partial-failure
rollback. 10 tests cover all specified behaviors plus rollback path.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat: add import_myst.py for importing MyST files from myst/* branches

Adds scripts/import_myst.py with import_page, git_show, list_myst_files,
list_rst_files, and do_import. Imported files are written as md-{name}.md
alongside existing RST files; importing is decoupled from swap activation.

Adds tests/test_import_myst.py covering single-page write, identical-skip,
warn-on-different-without-force, force-overwrite, and nested-path creation.
All 5 tests pass on Python 3.9.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat: add MyST swap exclude patterns and directive config to conf.py

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* feat: add swap-wrapped rendering targets to Makefile

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* feat: add swap pre/post build hooks for ReadTheDocs

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* feat: add empty _swap.txt, remove atexit from swap script

The atexit handler in --swap mode caused immediate restore on process
exit, breaking standalone usage. Makefile trap and RTD post_build
handle restore reliably.

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* feat: activate quick-start as MyST canary via swap mechanism

Imports docs/md-quick-start.md from origin/myst/current and adds
quick-start to docs/_swap.txt. Validates the swap pipeline end-to-end
on one page: import_myst pulls the MD via git show, swap_sources
renames md-quick-start.md to quick-start.md, sphinx-build renders
quick-start.html with zero MD-specific warnings, and restore reverses
the rename cleanly.

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* 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.

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* fix: re-import 4 canary md-*.md files with xref label fixes

Re-imports the dash-form-corrected versions of:
- contributing/md-development.md (added (coding-guidelines)= anchor)
- operation/md-upgrade-recovery.md (3 ref renames: how_it_works /
  cancelling_recovery -> dash form)
- vpp/configuration/dataplane/md-buffers.md (vpp_config_dataplane_physmem
  -> vpp-config-dataplane-physmem)
- vpp/configuration/dataplane/md-unix.md
  (vpp_config_dataplane_interface_rx_mode
  -> vpp-config-dataplane-interface-rx-mode)

Source: origin/myst/current commit 59fbe3ea. Verified locally: clean
swap-build no longer reports any of the 5 target labels (1 of 6 —
vpp-config-hugepages — remains because system.md isn't in the canary
swap list; that anchor lives there).

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* fix: re-add 4 canary md-*.md files deleted by 242b334a

Commit 242b334a accidentally staged deletions instead of modifications
because the working tree had unprefixed *.md files left over from an
incomplete swap-restore cycle. Re-imports the same 4 files from
origin/myst/current with the xref label fixes applied:

- contributing/md-development.md       — (coding-guidelines)= anchor
- operation/md-upgrade-recovery.md     — how_it_works → how-it-works,
                                         cancelling_recovery → cancelling-recovery
- vpp/configuration/dataplane/md-buffers.md — vpp_config_dataplane_physmem
                                              → vpp-config-dataplane-physmem
- vpp/configuration/dataplane/md-unix.md   — vpp_config_dataplane_interface_rx_mode
                                              → vpp-config-dataplane-interface-rx-mode

Source: origin/myst/current commit 59fbe3ea.

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* fix: resolve remaining xref label gaps in swap-active build

Three small additions clear the cross-reference warnings tied to
underscore-vs-dash label form mismatches and the vpp-config-hugepages
reference that previously needed system.md in the canary set.

- system.rst: add .. _vpp-config-hugepages: alongside the existing
  underscore label so memory.md references resolve regardless of
  whether system.md is swap-active.
- md-lcp.md: add (vpp_config_dataplane_lcp_ignore-kernel-routes)=
  alongside dash form (carries upstream from myst/current 079fa786).
- md-memory.md: add (vpp_config_dataplane_memory)= alongside dash
  form (also from myst/current 079fa786).

Local clean swap-build with 106 canaries:
  before: 305 warnings, 8 undefined-label entries in our scope
  after:  300 warnings, 0 undefined-label entries in our scope

Remaining undefined-label warnings (release-notes, prepare_commit)
are in documentation.rst and unrelated to the canary swap mechanism.

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* fix: re-add md-lcp.md and md-memory.md (deleted by 870c9e7e)

Same disaster pattern as 242b334a: a swap-restore cycle left
unprefixed *.md files in the working tree, and the subsequent
git add staged deletions instead of modifications. Restoring the
two affected md-*.md files from origin/myst/current 079fa786
(which has the dual underscore+dash anchors needed for the
swap-active build).

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* feat: expand canaries to 114; refresh 3 with cfgcmd body fix

Adds 8 new visual-validated canaries from the post-cfgcmd-fix
BackstopJS run (2026-04-29):

- configuration/policy/as-path-list
- configuration/policy/community-list
- configuration/policy/extcommunity-list
- configuration/policy/large-community-list
- configuration/policy/local-route
- configuration/policy/prefix-list
- configuration/service/salt-minion
- configuration/system/updates

Refreshes 3 existing canaries whose MD content changed via the
cfgcmd/opcmd single-line body fix on myst/current fc19ab5c:

- configuration/firewall/global-options
- configuration/firewall/groups
- configuration/policy/route

All 11 sourced from origin/myst/current. Net: 106 -> 114 canaries.

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* fix: re-import md-cloud-init.md (block 3 fix from myst/current)

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* feat(swap): import .md files and webp transition from myst/current

Selective import from origin/myst/current (cf9c9b34):
- Add/update 255 .md files (full MyST conversion plus webp ref updates)
- Delete 175 PNG/JPG from docs/_static/images (webp twins already present)
- Delete 5 autotest topology.png (webp twins already present)

Preserved on swap (untouched):
- All .rst files (incremental swap pattern)
- conf.py, _ext/, _include/*.txt, .gitignore
- 115 canary md-*.md files
- 7 superpowers/specs/*.md design docs
- Logos vyos-logo.png / vyos-logo-icon.png (referenced by conf.py)

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* chore(swap): remove canary md-*.md files and docs/superpowers

- Remove 115 canary md-*.md files (incremental swap helpers no longer needed)
- Remove 8 files under docs/superpowers (project planning/design docs that
  shouldn't ship in the documentation tree)

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* docs: address Copilot review feedback on imported MyST pages

Fix issues flagged by Copilot review on PR #1857 (the same content lives
in myst/current as the canonical source):

Real bugs:
- site-2-site-cisco.md: replace curly quote (U+2019) with ASCII apostrophe
- rsa-keys.md: fix typo "key-pair nam>>" → "key-pair name>"
- vmware.md: lowercase admonition directive (:::{NOTE} → :::{note})
- vpp/configuration/nat/index.md: remove blank line inside {include} fence

Grammar:
- vpp/configuration/interfaces/loopback.md: "bounded" → "bound"
- vpp/configuration/sflow.md: "VyOS support" → "VyOS supports"
- vpp/requirements.md: "bypass" → "bypasses"
- vpp/configuration/dataplane/interface.md: "configures" → "configure"

CI linter (IP addresses):
- nmp.md: wrap 8.8.8.8 example with stop/start_vyoslinter
- lac-lns.md: wrap LNS config block (contains 8.8.8.8)
- wan-load-balancing.md: wrap whole file (illustrative non-RFC IPs)
- policy/examples.md: replace 192.0.1.1 with RFC 5737 192.0.2.1

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* fix(swap): address Copilot review feedback on swap infrastructure

Category D — drop obsolete canary mechanism settings:
- conf.py: remove '**/md-*.md' from exclude_patterns (no canaries left)
- Makefile: replace malformed '*/_build/*' with '$(BUILDDIR)/**' and drop
  the '*/md-*' ignore (canary files no longer exist)

Category C — script robustness:
- import_myst.py:
  * list_myst_files() now raises SystemExit on git ls-tree failure instead
    of silently returning [] (would have masked typo'd --source refs)
  * list_rst_files() skips _build/ when scanning for .rst stems
  * import_page() rejects stems containing '..' or absolute paths and
    re-checks that the resolved destination stays under docs_dir
  * --dry-run uses a separate "would_import" counter; summary line now
    distinguishes dry-run from actual imports
- swap_sources.py:
  * parse_swap_list() reads with explicit encoding='utf-8'
  * do_restore() validates state file version + entry shape before
    renaming files; raises with actionable message on corruption
  * State file reads/writes use explicit encoding='utf-8' throughout

_swap.txt:
- Wrap long comment line to satisfy 80-character doc-linter limit

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* refactor(swap): rename imported .md files to md- prefix for swap mechanism

Restore the canary file naming convention that swap_sources.py expects:
the imported MyST pages now live as docs/<dir>/md-<name>.md alongside
the existing docs/<dir>/<name>.rst, so swap_sources.py --swap can rename
them into place at build time.

- 254 .md files renamed (every page with a matching .rst counterpart)
- 2 MyST-only pages left at their final names (no .rst exists, no swap
  needed): docs/copyright.md, docs/automation/terraform/terraformvyos.md

All 114 stems listed in docs/_swap.txt now have a corresponding
md-<name>.md source file ready to swap in.

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* docs: address CodeRabbit review feedback on imported MyST pages

Fix issues flagged by CodeRabbit on PR #1857. All issues are pre-existing
in the upstream RST docs and inherited by the MyST conversion.

Real bugs:
- inter-vrf-routing-vrf-lite.md: invalid IPv6 next-hop "2001:db8::*" →
  "2001:db8::1"
- ipsec-pa-route-based.md: vendor mislabel "Cisco" → "Palo Alto"
  (header on line 39 and "Monitoring on Cisco side" section heading)
- bgp-ipv6-unnumbered.md: AS number mismatch between configuration and
  verification output for both routers (Router A: 65020 → 64496;
  Router B: 65021 → 64499)
- qos.md: class 30 used "match ADDRESS20" instead of ADDRESS30 — broke
  the documented pattern (classes 10/20/30 → ADDRESS10/20/30)

Security:
- OpenVPN_with_LDAP.md: redact full PEM private key material from the
  three "set pki ... private key '...'" lines and from the embedded
  OpenVPN client <key> block; replace with <REDACTED> / ...REDACTED...
  placeholders. Public certificates retained.

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* feat(swap): default to serving MyST for all swapped pages

Replace the previously-curated 114-stem _swap.txt with the full set of
254 imported md-prefixed pages, so MD is served by default at build
time. To revert any specific page back to RST, remove its stem from
_swap.txt (or comment it out).

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* fix(ext): handle RST fallback in CmdInclude when _renderer absent

`cmdincludemd` is in `myst_fence_as_directive`, so MyST routes
fence blocks through `render_fence → render_restructuredtext →
MockRSTParser`. In that path `self.state` is a plain docutils Body
with no `_renderer`, crashing the build.

Fall back to `nested_parse` when `_renderer` is unavailable so the
directive works in both MyST and RST/MockRSTParser contexts.

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* feat(conf): copy .md sources into HTML output for plain-text serving

Adds a build-finished hook that mirrors every .md file from the Sphinx
source tree into the HTML output directory verbatim, making unrendered
MyST sources accessible alongside HTML renders at the same URL path.

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* docs: address review feedback from PR #1857

Fix conversion artifacts, typos, grammar errors, and technical
inaccuracies flagged by automated code review (Copilot + CodeRabbit).

Infrastructure: add root-level md-*.md exclusion to conf.py,
fix sphinx-autobuild ignore globs in Makefile.

Content: fix curly quotes, invalid Go panic() calls, shell quoting
in cURL examples, incorrect firewall command paths, typos across
22 documentation files, remove duplicate sections.

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

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

2 files changed, 192 insertions, 0 deletions

diff --git a/docs/introducing/md-about.md b/docs/introducing/md-about.md
new file mode 100644
index 00000000..ec4ff30d
--- /dev/null
+++ b/docs/introducing/md-about.md
@@ -0,0 +1,21 @@
+(about)=
+
+# About
+
+VyOS is an open-source network operating system that provides a single unified
+CLI and API to manage routing protocols, firewall and NAT, QoS, load balancing,
+DHCP and DNS servers, and many other features.
+
+VyOS runs on a wide variety of commodity hardware, virtual machines, and
+multiple cloud environments.
+
+We provide a dedicated user guide for each major
+VyOS release that receives long-term support (LTS). We maintain multiple user
+guide versions, all hosted at <https://docs.vyos.io>.
+To switch between versions, select the appropriate version in the bottom-right
+corner.
+
+VyOS CLI syntax may vary between major and sometimes minor releases. Always
+refer to the documentation matching your current running installation. If
+a change in the CLI is required, VyOS provides a migration script to handle
+the syntax adjustments. No user action is required.
diff --git a/docs/introducing/md-history.md b/docs/introducing/md-history.md
new file mode 100644
index 00000000..77b82986
--- /dev/null
+++ b/docs/introducing/md-history.md
@@ -0,0 +1,171 @@
+---
+description: |-
+  Overview of the VyOS project's history, from its 2013 fork of Vyatta Core
+  through each major LTS release. Covers release codenames, base Debian
+  versions, and the headline features introduced in each version.
+keywords: |-
+  vyos history, vyatta fork, lts release, scutum, circinus, sagitta,
+  equuleus, crux, debian
+---
+
+(history)=
+
+# History
+
+## In the beginning...
+
+There was a network operating system based on Debian GNU/Linux, called
+Vyatta. [^footnote-1] Introduced in 2006, it served as a great free-software alternative
+to proprietary products. Vyatta came in two editions: Vyatta Core
+(formerly known as Vyatta Community Edition), which was free software, and
+Vyatta Subscription Edition, which included proprietary features and was
+available only to paying customers.
+
+Brocade Communications Systems acquired Vyatta in 2012. Shortly after, Brocade
+renamed Vyatta Subscription Edition to Brocade vRouter, discontinued Vyatta
+Core, and shut down the community forum without notice. The bug tracker and Git
+repositories were closed the following year.
+
+By the time Brocade acquired Vyatta, the development of Vyatta Core had
+already stagnated. The focus had shifted to Vyatta Subscription Edition,
+where core components were replaced with proprietary software. As a result,
+Vyatta Core received fewer new features, and some of those added faced issues.
+
+In 2013, shortly after Vyatta Core was discontinued, the community forked its
+final version (6.6R1) to create the VyOS project. In 2014, the maintainers
+established a company to fund VyOS development through technical support,
+consulting services, and LTS release access subscriptions. The company was
+originally named Sentrium and was later reorganized under the VyOS brand.
+
+## Major releases
+
+VyOS originally named its major versions after elements by atomic number.
+Beginning with version 1.2, this naming scheme was changed. It now uses the
+Latin names of constellations recognized by the International Astronomical
+Union ([IAU](https://en.wikipedia.org/wiki/IAU_designated_constellations_by_area)),
+ordered by their solid angle area, beginning with the smallest.
+
+### Hydrogen (1.0)
+
+Released just in time for the holidays on 22 December 2013, Hydrogen was
+the first major VyOS release. It fixed features that were broken in
+Vyatta Core 6.6, such as IPv4 BGP peer groups and DHCPv6 relay, and
+introduced command scripting, a task scheduler, and web proxy LDAP
+authentication.
+
+### Helium (1.1)
+
+Helium, released on 9 October 2014, marked the first anniversary of the
+VyOS Project. The release introduced an event handler, L2TPv3 support,
+802.1ad (QinQ), and IGMP proxy, as well as experimental support for VXLAN
+and DMVPN. Notably, DMVPN remained non-functional in Vyatta Core due to its
+reliance on a proprietary NHRP implementation.
+
+### Crux (1.2)
+
+Crux (the Southern Cross) was released on 28 January 2019 and marked a
+departure from legacy Vyatta codebase and the start of the migration from
+Perl to Python as the primary language. The underlying base system was
+upgraded from Debian 6 (Squeeze) to Debian 8 (Jessie).
+
+Crux introduced many new features, some of the most noteworthy are:
+an mDNS repeater, a broadcast relay, a high-performance PPPoE server,
+an HFSC scheduler, and support for Wireguard, unicast VRRP, RPKI for BGP,
+and fully 802.1ad-compliant QinQ ethertype. The telnet server and support
+for P2P filtering were removed.
+
+Crux was the first VyOS release to feature a modular image build system.
+CLI definitions were written using an XML syntax automatically checked
+against a schema at build time. Python APIs were introduced for command
+scripting and configuration migration. New Perl code and old-style (non-XML)
+command definition were no longer accepted from that point.
+
+Crux reached the end of support in 2023.
+
+### Equuleus (1.3)
+
+Equuleus (the Little Horse) was a long-term support version released
+on 21 December 2021, just in time for the winter holidays.
+
+Equuleus brought many long-awaited features, most notably an SSTP VPN
+server, an IPoE server, an OpenConnect VPN server, and a serial console
+server. It also introduced reworked support for WWAN interfaces, support
+for GENEVE and MACSec interfaces, VRF, IS-IS routing, and preliminary support
+for MPLS and LDP.
+
+Equuleus reached the end of support in 2025.
+
+### Sagitta (1.4)
+
+Sagitta (the Arrow), the current LTS release, became generally available on
+4 June 2024. Its development began in late 2021 and focused on eliminating
+remaining legacy components and reworking core subsystems.
+
+The transition to XML-defined command definitions and script refactoring with
+separate verify, update, and apply stages were completed. The firewall
+subsystem was rebuilt on nftables, introducing interface-independent rulesets
+and the reimplemented zone-based firewall model. The PKI subsystem was
+redesigned to manage cryptographic material directly within the configuration
+file.
+
+Sagitta introduced rollback without reboot, support for Babel and PIM6 routing
+protocols, failover routes, segment routing, NAT64, an IKEv2 remote-access VPN
+server, Zabbix monitoring, HTTP load balancing, and configuration
+synchronization using the HTTP API.
+
+The underlying base system was upgraded to Debian 12 (Bookworm).
+
+### Circinus (1.5)
+
+Circinus (the Drawing Compass) became generally available as an LTS release on
+31 March 2026. Its development began in 2024 and focused on major performance
+upgrades and modernizing core subsystems.
+
+Circinus introduces several major architectural improvements, most notably an
+optional VPP-based accelerated dataplane. Using the DPDK driver, this dataplane
+can offer performance up to 15x faster than the Linux kernel dataplane and
+allows administrators to selectively enable hardware acceleration on a
+per-interface and per-feature basis.
+
+Other significant additions and updates include:
+
+- A high-performance kernel-mode NetFlow sensor based on ipt-netflow,
+  replacing the older pmacct implementation.
+- Unification of sFlow to exclusively use the much faster hsflowd
+  implementation.
+- Transition of the DHCP server to a Kea-based implementation, replacing the
+  legacy, end-of-life ISC DHCPD.
+- A completely rewritten WAN load balancing implementation to resolve
+  long-standing stability issues and introduce support for firewall groups in
+  load balancing rules.
+- A new `execute` operational mode command family to separate action commands
+  that do not depend on or modify system configuration.
+
+The release also cleans up several legacy and underutilized components.
+FastNetMon was removed, OpenVPN support for Blowfish and Twofish ciphers was
+dropped for security reasons, and the Salt minion integration was deprecated.
+
+Like Sagitta (1.4), the underlying base system for Circinus remains Debian 12
+(Bookworm).
+
+### Scutum (1.6)
+
+Scutum (the Shield) is the codename for the upcoming development
+branch. VyOS 1.6 Scutum has not been released yet.
+
+## A note on copyright
+
+Unlike Vyatta, VyOS has never had closed-source code and never will.
+The only proprietary material in VyOS is non-code assets, such as
+graphics and the trademark "VyOS". [^footnote-2]
+
+Note that we do not provide support for images distributed by a third party.
+See the
+[artwork license](https://github.com/vyos/vyos-build/blob/current/LICENSE.artwork)
+and the end-user license agreement at `/usr/share/vyos/EULA` in
+any pre-built image for more information.
+
+[^footnote-1]: From the Sanskrit adjective "Vyātta" (व्यात्त), meaning opened.
+
+[^footnote-2]: This is similar to how Linus Torvalds owns the Linux trademark.
+