feat: Collapsed Data Center Fabric JVD — docs, snips, BYOAI

data_center/adc/collapsed_dc_fabric/README.md

@@ -16,6 +16,17 @@ Validated configurations for the Juniper Validated Design *"Collapsed Data Cente
 
 <img width="678" alt="Collapsed Data Center Fabric architecture" src="https://github.com/user-attachments/assets/52e20a5a-127e-4947-97ea-0f7ded3f5431" />
 
+## Documentation
+
+In-repo design corpus — faithful markdown conversions of the published JVD PDFs:
+
+| Doc | Contents |
+|---|---|
+| [Datasheet](documentation/datasheet.md) | One-page quick reference |
+| [Solution overview](documentation/solution-overview.md) | Executive summary, use cases, platforms |
+| [Design guide](documentation/design-guide.md) | Architecture, direct leaf-to-leaf peering, config walkthrough |
+| [Test report brief](documentation/test-report-brief.md) | Platforms, features, convergence, scale |
+
 ## Hardware
 
 | Juniper Product | Role | Hostnames |

data_center/adc/collapsed_dc_fabric/configuration/snips/README.md

@@ -0,0 +1,59 @@
+# Collapsed Data Center Fabric — Configuration Snippets
+
+Reusable, templated config fragments extracted from the sanitized JVD
+configurations under [conf/](../conf/). Each snippet contains:
+
+- A structured header (Topic, Variant, Seen on, Highlights, Pair with, Variables).
+- `$VARIABLE` placeholders for tunable values; see [_variables.md](_variables.md)
+  for the master glossary.
+
+The collapsed fabric is a **two-switch** EVPN-VXLAN fabric — the two leaves *are*
+the fabric and peer directly (no spine tier). Both switches run **Junos OS**
+(baseline QFX5120-48Y), so every snip lives under `junos/`.
+
+## Layout
+
+```
+snips/
+├── _variables.md
+└── junos/
+    ├── transport/    # Direct leaf-to-leaf eBGP underlay + EVPN overlay
+    ├── services/     # VLAN-aware MAC-VRF EVPN-VXLAN
+    └── interfaces/   # ESI-LAG access, anycast IRB gateway, loopback
+```
+
+## Snippet headers — `Seen on:` and `Pair with:`
+
+- **`Seen on:`** — every device in [`../conf/`](../conf/) that contains this exact
+  pattern. Both devices are Junos, so the `EVO:` line is always `(none)`.
+- **`Pair with:`** — other snippets in this library that work together. All
+  `Pair with:` references are reciprocal.
+
+## Snip index
+
+### Transport (direct leaf-to-leaf)
+
+| Snip | Purpose |
+|---|---|
+| [junos/transport/collapsed-underlay-ebgp.conf](junos/transport/collapsed-underlay-ebgp.conf) | eBGP underlay directly between the two collapsed leaves (l3clos-l) |
+| [junos/transport/collapsed-evpn-overlay.conf](junos/transport/collapsed-evpn-overlay.conf) | eBGP EVPN overlay directly between the two leaves over loopbacks (l3clos-l-evpn) |
+
+### Services
+
+| Snip | Purpose |
+|---|---|
+| [junos/services/mac-vrf-evpn-vxlan.conf](junos/services/mac-vrf-evpn-vxlan.conf) | VLAN-aware MAC-VRF (evpn-1), 1 VNI per VLAN, per-VNI route targets |
+
+### Interfaces
+
+| Snip | Purpose |
+|---|---|
+| [junos/interfaces/esi-lag-access.conf](junos/interfaces/esi-lag-access.conf) | All-active ESI-LAG for multihomed server / access switch |
+| [junos/interfaces/irb-anycast-gateway.conf](junos/interfaces/irb-anycast-gateway.conf) | Distributed anycast IRB L3 gateway for a fabric VLAN |
+| [junos/interfaces/loopback.conf](junos/interfaces/loopback.conf) | lo0 router-id / VTEP / per-VRF loopbacks |
+
+## Related
+
+- Design corpus: [`../../documentation/`](../../documentation/) (design guide, solution overview, test report brief, datasheet).
+- BYOAI assistant: [byoai/README.md](byoai/README.md).
+- Scale up: [3-stage data center snips](../../../3stage_dc/configuration/snips/).

data_center/adc/collapsed_dc_fabric/configuration/snips/_variables.md

@@ -0,0 +1,46 @@
+# Snip Variable Reference — Collapsed Data Center Fabric
+
+Variables used across the `collapsed_dc_fabric` snip library. Replace `$VARIABLE`
+placeholders with site-specific values when adapting snips to a new deployment.
+JVD-wide constants (group names `l3clos-l` / `l3clos-l-evpn`, policy names
+`BGP-AOS-Policy` / `EVPN_EXPORT`, the `evpn-1` MAC-VRF instance) are left literal
+because they *are* the abstraction the JVD documents.
+
+Both collapsed switches run **Junos OS** (baseline QFX5120-48Y), so every snip
+lives under `junos/` — there is no `evo/` tree.
+
+## Transport (direct leaf-to-leaf)
+
+| Variable | Example | Used in |
+|----------|---------|---------|
+| `$UNDERLAY_BFD_MS` | `1000` | collapsed-underlay-ebgp |
+| `$OVERLAY_BFD_MS` | `3000` | collapsed-evpn-overlay |
+| `$BFD_MULTIPLIER` | `3` | both |
+| `$PEER_LINK_IP` | `10.0.3.0` | collapsed-underlay-ebgp |
+| `$LOCAL_LINK_IP` | `10.0.3.1` | collapsed-underlay-ebgp |
+| `$PEER_LOOPBACK` | `192.168.253.1` | collapsed-evpn-overlay |
+| `$LOCAL_LOOPBACK` | `192.168.253.0` | collapsed-evpn-overlay |
+| `$PEER_DESCRIPTION` | `facing_dc3-rack-001-leaf2` | both |
+| `$PEER_AS` | `64801` | both |
+
+## Services
+
+| Variable | Example | Used in |
+|----------|---------|---------|
+| `$VNI` | `10400` | mac-vrf-evpn-vxlan |
+| `$VNI_RT` | `target:10400:1` | mac-vrf-evpn-vxlan |
+
+## Interfaces
+
+| Variable | Example | Used in |
+|----------|---------|---------|
+| `$AE_IFD` | `ae1` | esi-lag-access |
+| `$AE_DESCRIPTION` | `to.dc3-rack-001-sys001` | esi-lag-access |
+| `$ESI_VALUE` | `00:02:00:00:00:00:01:00:00:01` | esi-lag-access |
+| `$LACP_SYSTEM_ID` | `02:00:00:00:00:01` | esi-lag-access |
+| `$VLAN_MEMBERS` | `vn400 vn401` | esi-lag-access |
+| `$IRB_UNIT` | `400` | irb-anycast-gateway |
+| `$IRB_ADDRESS` | `10.0.0.1/24` | irb-anycast-gateway |
+| `$ANYCAST_MAC` | `00:1c:73:00:00:01` | irb-anycast-gateway |
+| `$LO_UNIT` | `0` | loopback |
+| `$LO_IPV4` | `192.168.253.0/32` | loopback |

data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/DEFAULTS.md

@@ -0,0 +1,49 @@
+# Auto-Fill Defaults
+
+This file is part of the [BYOAI](README.md) corpus. It gives the deterministic JVD lab-default values the AI uses in `auto` mode (or when the user short-circuits with `all defaults` / `use defaults` / `skip`). It is bundled into [`jvd-collapsed-snips.md`](jvd-collapsed-snips.md) by `regenerate-bundle.sh`.
+
+Use these values EXACTLY. Do not invent alternative defaults. Every value the AI auto-fills MUST be listed in the output's `Inputs used:` block so the user can rerun with edits. Addresses below are the JVD lab's actual values (from each device `.conf`, generated by Juniper Apstra) — substitute site values when deploying.
+
+---
+
+## Device inventory (the collapsed topology)
+
+| Device | Platform | OS | Role | Loopback | AS |
+|--------|----------|----|------|----------|----|
+| `leaf1_qfx5120-48y` | QFX5120-48Y | Junos | Collapsed-spine leaf 1 | `192.168.253.0` | `64800` |
+| `leaf2_qfx5120-48y` | QFX5120-48Y | Junos | Collapsed-spine leaf 2 | `192.168.253.1` | `64801` |
+| `external router` | MX204 | Junos | External gateway | — | — |
+
+> The JVD validates five collapsed-spine platforms (QFX5120-48Y, QFX5130-32CD, QFX5700, ACX7100-48L, PTX10001-36MR); the configs use the QFX5120-48Y baseline. The two leaves are eBGP peers with each other — leaf1 peer-as toward leaf2 is `64801` and vice-versa.
+
+**Device-choice shortcut** (offered in the clarifying question):
+- `LEAF-PAIR` → `leaf1_qfx5120-48y` + `leaf2_qfx5120-48y`
+
+---
+
+## Feature defaults
+
+| Variable | Default | Notes |
+|----------|---------|-------|
+| `$UNDERLAY_BFD_MS` | `1000` | direct underlay BFD |
+| `$OVERLAY_BFD_MS` | `3000` | direct EVPN overlay BFD (multihop) |
+| `$BFD_MULTIPLIER` | `3` | both |
+| `$PEER_AS` | `64801` (from leaf1) / `64800` (from leaf2) | the *other* collapsed switch |
+| `$LOCAL_LOOPBACK` | `192.168.253.0` (leaf1) / `192.168.253.1` (leaf2) | overlay local-address |
+| `$PEER_LOOPBACK` | `192.168.253.1` (from leaf1) | overlay peer (other leaf) |
+| `$PEER_LINK_IP` / `$LOCAL_LINK_IP` | `10.0.3.x` /31 | direct underlay p2p link |
+| `$VNI` | `10400` | first fabric VNI |
+| `$VNI_RT` | `target:10400:1` | per-VNI route target |
+| `$IRB_UNIT` | `400` | first routed VLAN IRB unit |
+| `$IRB_ADDRESS` | `10.0.0.1/24` | anycast gateway address (identical on both switches) |
+| `$ANYCAST_MAC` | `00:1c:73:00:00:01` | anycast gateway MAC (identical on both switches) |
+| `$ESI_VALUE` | `00:02:00:00:00:00:01:00:00:01` | ESI-LAG ESI (identical on both switches) |
+| `$LACP_SYSTEM_ID` | `02:00:00:00:00:01` | ESI-LAG LACP system-id (identical on both switches) |
+
+---
+
+## Literal constants (never templated)
+
+- Fabric BGP groups: `l3clos-l` (direct underlay), `l3clos-l-evpn` (direct overlay).
+- Policies: `BGP-AOS-Policy`, `EVPN_EXPORT`.
+- MAC-VRF instance: `evpn-1` (VLAN-aware, `default-gateway do-not-advertise`).

data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/MANIFEST.json

@@ -0,0 +1,112 @@
+{
+  "schema_version": 1,
+  "description": "BYOAI snip manifest. Fetch the entries you need from raw_url; do NOT fetch every snip. See byoai/SYSTEM_PROMPT.md for the selection rules.",
+  "raw_url_base": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips",
+  "snip_count": 6,
+  "snips": [
+    {
+      "path": "junos/interfaces/esi-lag-access.conf",
+      "os": "junos",
+      "category": "interfaces",
+      "name": "esi-lag-access",
+      "topic": "ESI-LAG all-active access (multihomed server / access switch)",
+      "seen_on": [
+        "leaf1_qfx5120-48y",
+        "leaf2_qfx5120-48y"
+      ],
+      "size_bytes": 1466,
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/junos/interfaces/esi-lag-access.conf"
+    },
+    {
+      "path": "junos/interfaces/irb-anycast-gateway.conf",
+      "os": "junos",
+      "category": "interfaces",
+      "name": "irb-anycast-gateway",
+      "topic": "Anycast IRB gateway for a fabric VLAN",
+      "seen_on": [
+        "leaf1_qfx5120-48y",
+        "leaf2_qfx5120-48y"
+      ],
+      "size_bytes": 1002,
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/junos/interfaces/irb-anycast-gateway.conf"
+    },
+    {
+      "path": "junos/interfaces/loopback.conf",
+      "os": "junos",
+      "category": "interfaces",
+      "name": "loopback",
+      "topic": "Loopback lo0 addressing (router-id / VTEP / per-VRF)",
+      "seen_on": [
+        "leaf1_qfx5120-48y",
+        "leaf2_qfx5120-48y"
+      ],
+      "size_bytes": 895,
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/junos/interfaces/loopback.conf"
+    },
+    {
+      "path": "junos/services/mac-vrf-evpn-vxlan.conf",
+      "os": "junos",
+      "category": "services",
+      "name": "mac-vrf-evpn-vxlan",
+      "topic": "VLAN-aware MAC-VRF EVPN-VXLAN instance",
+      "seen_on": [
+        "leaf1_qfx5120-48y",
+        "leaf2_qfx5120-48y"
+      ],
+      "size_bytes": 1484,
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/junos/services/mac-vrf-evpn-vxlan.conf"
+    },
+    {
+      "path": "junos/transport/collapsed-evpn-overlay.conf",
+      "os": "junos",
+      "category": "transport",
+      "name": "collapsed-evpn-overlay",
+      "topic": "Direct leaf-to-leaf eBGP EVPN overlay (collapsed spine)",
+      "seen_on": [
+        "leaf1_qfx5120-48y",
+        "leaf2_qfx5120-48y"
+      ],
+      "size_bytes": 1991,
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/junos/transport/collapsed-evpn-overlay.conf"
+    },
+    {
+      "path": "junos/transport/collapsed-underlay-ebgp.conf",
+      "os": "junos",
+      "category": "transport",
+      "name": "collapsed-underlay-ebgp",
+      "topic": "Direct leaf-to-leaf eBGP underlay (collapsed spine)",
+      "seen_on": [
+        "leaf1_qfx5120-48y",
+        "leaf2_qfx5120-48y"
+      ],
+      "size_bytes": 1652,
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/junos/transport/collapsed-underlay-ebgp.conf"
+    }
+  ],
+  "reference_files": [
+    {
+      "path": "_variables.md",
+      "kind": "glossary",
+      "topic": "Glossary of $VAR placeholders used across all snips",
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/_variables.md"
+    },
+    {
+      "path": "byoai/TIERS.md",
+      "kind": "reference",
+      "topic": "Per-service snip lists for `minimum` vs `as-deployed` configuration form",
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/TIERS.md"
+    },
+    {
+      "path": "byoai/DEFAULTS.md",
+      "kind": "reference",
+      "topic": "Auto-fill rules: lab-default loopbacks, AS numbers, VNIs, RD/RT, ESI shape",
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/DEFAULTS.md"
+    },
+    {
+      "path": "byoai/OUTPUT_FORMAT.md",
+      "kind": "reference",
+      "topic": "Required output format: YAML Inputs block, per-device fenced blocks, Notes section",
+      "raw_url": "https://raw.githubusercontent.com/Juniper/jvd/main/data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/OUTPUT_FORMAT.md"
+    }
+  ]
+}

data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/MENU.md

@@ -0,0 +1,37 @@
+# Collapsed Data Center Fabric BYOAI — Full Query Menu
+
+The always-current catalog of generation asks for the **Collapsed Data Center Fabric** JVD — a two-switch EVPN-VXLAN collapsed-spine fabric (no separate spine tier) built with Juniper Apstra for small data centers. All items render on the chosen device(s) with the chosen form tier (`minimum` / `as-deployed`).
+
+## Fabric transport (direct leaf-to-leaf)
+
+- `Generate the direct leaf-to-leaf underlay for <leaf>` — eBGP underlay between the two collapsed switches (l3clos-l)
+- `Generate the direct EVPN overlay for <leaf>` — eBGP EVPN overlay over loopbacks (l3clos-l-evpn)
+
+## Services (L2 / L3)
+
+- `Generate a VLAN-aware MAC-VRF` — evpn-1, 1 VNI per VLAN, per-VNI route targets
+- `Add a VLAN with an anycast IRB gateway` — MAC-VRF VNI + anycast IRB (identical mac + address on both switches)
+
+## Access / multihoming
+
+- `Add an ESI-LAG to <leaf-pair>` — all-active multihomed access (AE + ESI + LACP, matched on both switches)
+
+## Interfaces
+
+- `Generate the loopback for <leaf>` — lo0 router-id / VTEP / per-VRF loopbacks
+
+## Greenfield / turn-up
+
+- `Build a full collapsed two-switch turn-up` — direct underlay + overlay + loopback + MAC-VRF + anycast IRB + ESI-LAG
+
+## Audit / explain
+
+- `Explain the collapsed-spine architecture (why no spine tier)`
+- `Explain direct leaf-to-leaf eBGP underlay + EVPN overlay`
+- `Explain the VLAN-aware MAC-VRF and anycast IRB gateway model`
+- `Explain ESI-LAG all-active multihoming across two collapsed switches`
+- `When should I use collapsed vs 3-stage?`
+
+---
+
+Don't see what you need? Describe it and the assistant will tell you whether the Collapsed Data Center Fabric JVD covers it (and point you to the Access-Switches JVDE or 3-stage DC JVD for scale-out).

data_center/adc/collapsed_dc_fabric/configuration/snips/byoai/OUTPUT_FORMAT.md

@@ -0,0 +1,70 @@
+# Output Format
+
+This file is part of the [BYOAI](README.md) corpus. It defines the exact shape every generation must take. Bundled into [`jvd-collapsed-snips.md`](jvd-collapsed-snips.md) by `regenerate-bundle.sh`.
+
+## 1. `Inputs used:` block (always first)
+
+Every generation begins with a YAML comment block listing **every** value picked or accepted:
+
+```yaml
+# Inputs used:
+# mode: auto                   # or "interview"
+# form: as-deployed            # or "minimum"
+# devices:
+#   leaf1: { name: <hostname>, os: junos, role: collapsed-leaf, loopback4: <addr>, as: <asn> }
+#   leaf2: { ... }
+# features:
+#   - { kind: <collapsed-fabric|mac-vrf|esi-access>,
+#       vni: <int>,                 # MAC-VRF VNI
+#       vni_rt: <target:...>,        # per-VNI route target
+#       irb_unit: <int>,             # anycast IRB unit
+#       irb_address: <addr/len>,     # anycast gateway (same on both switches)
+#       anycast_mac: <mac>,          # anycast gateway MAC (same on both switches)
+#       esi: <hex>,                  # ESI-LAG ESI (same on both switches)
+#       lacp_system_id: <mac> }      # ESI-LAG LACP system-id (same on both switches)
+# snips_used:
+#   - junos/services/mac-vrf-evpn-vxlan.conf
+#   - junos/interfaces/irb-anycast-gateway.conf
+#   - ...
+```
+
+This block makes every generation reproducible — the user can paste it back to regenerate the same output.
+
+## 2. One fenced `text` block per device
+
+Each device block starts with a `# device:` label and groups its snips with `/* snips/<path> */` section comments:
+
+```text
+# device: <hostname>
+/* snips/<path-to-snip>.conf */
+<rendered config block>
+
+/* snips/<path-to-next-snip>.conf */
+<rendered config block>
+```
+
+Drop the leading C-style `/* … */` documentation header from each snip when emitting. Keep one `/* snips/<path> */` line as the section comment.
+
+## 3. `Notes:` section (always last)
+
+Bullets covering:
+
+- Snips intentionally omitted (and why).
+- Inputs defaulted because the user did not provide them.
+- Cross-device consistency the user must verify:
+  - ESI-LAG **ESI value** and **LACP system-id** MUST be identical on both collapsed switches for the same AE bundle (that is what makes it all-active).
+  - The anycast IRB **`mac`** and gateway **address** MUST be identical on both switches for the same VLAN.
+  - MAC-VRF **per-VNI route-targets** MUST match across both switches.
+  - The two leaves are eBGP peers with each other; each has its own loopback and AS.
+- Anything by-pattern rather than validated on that exact device (e.g., a user-supplied hostname not in any snip's `Seen on:` list).
+- Collapsed reminders: the VLAN-aware MAC-VRF uses `default-gateway do-not-advertise` (each switch owns its anycast gateway locally); the direct EVPN overlay (`l3clos-l-evpn`) runs over loopbacks and the underlay (`l3clos-l`) over the point-to-point links between the two switches.
+
+## Refusal
+
+If the request cannot be fulfilled from the snip library, do not apologise. Say exactly:
+
+```
+I cannot generate this from the snip library because <one reason>.
+```
+
+…and stop.