aci-sim/docs/CONTRACT.md

autoACI ⇄ APIC/NDO REST CONTRACT (what the simulator must satisfy)

Distilled from a read-only audit of ~/autoACI/backend (services/aci_connector.py, ndo_connector.py, routers/topology.py, routers/ndo.py, routers/fabric_build.py, services/acipy_exec.py, plugins/*). This is the authoritative contract the sim emulates. Do NOT re-explore autoACI; trust this file. If something here is ambiguous, prefer the behavior that makes autoACI render.

autoACI connects to three host identities, each https://{host} with verify=False:

• Site-A APIC, Site-B APIC (each logged in separately; autoACI tracks sites[].{host,asn} and prefixes node IDs by site when >1 site), and
• ND / NDO (separate auth + endpoints).

---

1. APIC — authentication

• POST /api/aaaLogin.json body {"aaaUser":{"attributes":{"name":<user>,"pwd":<pwd>}}}. name may be a bare username (admin) or domain-qualified (apic:<domain>\<user> or <domain>\<user>, e.g. apic:local\admin) — PR-15: aci-py's APIC connector sends the domain-qualified form by default, matching real APIC's local-login-domain behavior. auth.py::_bare_username() strips an optional apic:<domain>\/<domain>\ prefix before the credential compare, so both forms authenticate identically; the domain segment itself is not validated (this sim has no concept of configured login domains — any domain string is accepted). Credentials (post-strip) are checked against SIM_USERNAME/SIM_PASSWORD (default admin/cisco; see README §Configuration) — a mismatch (either form) returns a 401 APIC error envelope, never a bare token. Admin-account wizard (topology auth: section): aci-sim init's Step 0 writes an auth: {username, password} section into topology.yaml (topology/schema.py's Auth model); aci-sim run resolves SIM_USERNAME/SIM_PASSWORD with this precedence (highest first): (1) the caller's shell already has SIM_USERNAME set — wins outright, auth: is ignored; (2) topology.yaml has an auth: section — its username/ password are injected; (3) neither — nothing injected, this sim falls back to the hardcoded admin/cisco default documented above. cli.py's resolve_admin_credentials() implements this precedence and is unit-tested directly (tests/test_admin_account.py). NDO is NOT affected — ndo/app.py's POST /api/v1/auth/login/POST /login (§7 below) accept any credential by design and never validate anything against auth.ndo_username/ndo_password; those two fields (set only when the wizard's ndo_same_account answer is "no") are stored for informational parity only. Response on success: {"imdata":[{"aaaLogin":{"attributes":{"token":"<t>","refreshTimeoutSeconds":"600"}}}]}. Token also returned as APIC-cookie cookie; subsequent requests send that cookie. Sessions expire after refreshTimeoutSeconds (600s); every query/write route requires a live, unexpired APIC-cookie or returns a 403 APIC error envelope (text="Token was invalid (Error: Token timeout)", code="403"). A malformed login body (wrong shape / non-JSON) returns a 400 APIC error envelope, never FastAPI's raw {"detail": [...]} validation-error shape.
• GET /api/aaaRefresh.json → requires a valid existing APIC-cookie; renews its expiry to a full refreshTimeoutSeconds and returns the same aaaLogin envelope (autoACI refreshes every ~240s). Without/with an invalid cookie → 403 envelope.
• POST /api/aaaLogout.json body {"aaaUser":{"attributes":{"name":<user>}}} — invalidates the server-side session in addition to clearing the cookie.
• During/after login autoACI probes: GET /api/class/topSystem.json?query-target-filter=eq(topSystem.role,"controller")&page-size=1 and GET /api/mo/uni/userprofile-<user>.json?query-target=subtree&target-subtree-class=aaaUserDomain.

2. APIC — the three query shapes + full param grammar

1. Class query — GET /api/class/{class}.json with any of:
   • page-size (always; default 500, clamped to [1, 5000]), page (always; 0-indexed, must be >= 0). A non-numeric or out-of-range page/page-size yields a 400 APIC error envelope (code="107"), never a bare 500 or silent truncation.
   • query-target-filter={expr} (filter grammar §4)
   • rsp-subtree=children|full + rsp-subtree-class={c1,c2,...} (modern subtree)
   • query-target=subtree + target-subtree-class={c1,c2,...} (legacy subtree)
2. MO/DN query — GET /api/mo/{dn}.json with optional query-target=subtree + target-subtree-class={...}. DNs contain slashes inside brackets: subnet-[10.0.0.1/24], pathep-[eth1/9], rsdomAtt-[uni/phys-X] — bracket-aware DN parsing required. GET/POST/DELETE /api/node/mo/{dn}.json is a full alias of /api/mo/{dn}.json (PR-10) — real APIC serves both; the sim's API Inspector / aci_rest-module callers may use either interchangeably with identical behavior.
3. Node-scoped class query — GET /api/node/class/{dn}/{class}.json with optional query-target-filter. Used for node-local faultInst (e.g. .../topology/pod-1/node-101/faultInst.json). Fabric-wide form: GET /api/node/class/{class}.json (no topology/pod-X/node-Y DN prefix at all — just the bare class name) is also supported and is equivalent to GET /api/class/{class}.json (same result set, real APIC behavior). The sim distinguishes the two by whether the path segment after /api/node/class/ contains a /: a node-scoped DN always does, the fabric-wide form never does.

Response envelope (always):

{"imdata":[ {"<class>":{"attributes":{...}, "children":[ {"<child>":{"attributes":{...}}} ]}} ], "totalCount":"<N>"}

• children present only when a subtree mode was requested (children/full nest children; rsp-subtree-class/target-subtree-class filter which descendant classes appear).
• totalCount is a STRING; used for pagination (client loops page until a short page).
• Subtree responses may return children before parents → consumers do two-pass parsing; the sim may emit any order but MUST include all requested descendants.

2a. APIC — query subscriptions + websocket push

All three query shapes in §2 accept ?subscription=yes. The response is the normal §2 envelope PLUS a top-level subscriptionId string sitting alongside imdata/totalCount (NOT nested inside them):

{"imdata":[...], "totalCount":"<N>", "subscriptionId":"<id>"}

Without ?subscription=yes, the response has no subscriptionId key — byte-identical to a pre-subscription-feature query. This is a strict backward-compat requirement, not a default choice.

Scope: a class-query subscription (/api/class/{cls}.json) watches every MO of that class fabric-wide. A DN-scoped subscription (/api/mo/{dn}.json, /api/node/class/{dn}/{cls}.json) watches that DN and its entire subtree.

Websocket: GET /socket<token> — <token> is the same APIC-cookie token from aaaLogin (no separator, literal path concatenation, matching real APIC). Unknown/expired token → connection rejected before accept. One live connection per token.

Push event (sent on the matching token's websocket after a write commits):

{"subscriptionId":["<id>",...], "imdata":[{"<class>":{"attributes":{...,"status":"created|modified|deleted","dn":"<dn>"}}}]}

• subscriptionId is a list — every subscription on that token's session that matched the change (a client can hold multiple overlapping subs).
• status is created (DN didn't previously exist), modified (DN already existed), or deleted (DELETE, or POST body status="deleted").
• A DELETE on a DN with children emits one event per removed MO in the subtree (root + all descendants), each carrying its own class/dn/status, so both class-scoped and DN-scoped subscribers see everything actually removed.

Refresh: GET /api/subscriptionRefresh.json?id=<id> — always 200 ({"imdata":[],"totalCount":"0","subscriptionId":"<id>"}), including for an unknown/expired id (real APIC does not error a stale refresh). Default subscription TTL is 90s, matching real APIC, renewed by this call.

Lifecycle: disconnecting the websocket immediately drops every subscription owned by that connection's token — a subsequent matching change is silently skipped (no error), same as a DN/class nobody subscribed to.

Implementation: aci_sim/rest_aci/subscriptions.py (in-memory registry + notify) and aci_sim/rest_aci/app.py (route wiring). See README §10a for the user-facing walkthrough.

3. APIC — write path (Fabric Build apply)

• POST /api/mo/{dn}.json body {"<class>":{"attributes":{"name":...,"dn":...,"status":"created|modified|deleted"?}, "children":[...]}}. Response {"imdata":[{"<class>":{"attributes":{"dn":...,"status":"created"}}}],"totalCount":"1"} (HTTP 200). Nested children in the body must be upserted too (recursively). status:"deleted" removes.
• Writes must upsert into the live MIT so a later GET reflects them (read-back verification).
• Atomic (all-or-nothing): the entire body (root + every nested child, recursively) is shape-validated before any store mutation happens. A malformed node anywhere in the tree (e.g. a children entry that isn't a single-key {className: {...}} object) rejects the whole POST with a 400 APIC error envelope and leaves the store completely untouched — including MOs earlier in traversal order that would otherwise have been written first. Mirrors real APIC POST semantics.
• Canonical RN synthesis: a child posted without an explicit dn gets its RN derived from the class's real RN prefix (e.g. fvBD → BD-{name}, fvAEPg → epg-{name}, fvSubnet → subnet-[{ip}]), not a generic {class}-{name} guess — so it lands on the same DN a canonical GET or a later explicit-dn POST would use (no orphan duplicates). Classes without a known template fall back to {class}-{name}.
• Node registration reaction: initial_fabric_discovery/add_leaf_switch_pair/add_spine_switch POST fabricNodeIdentP at uni/controller/nodeidentpol/nodep-{id}. The sim reacts by materializing a full node-registration MO set, not just a bare fabricNode: fabricNode, topSystem (loopback + OOB addresses via the same scheme every boot-seeded node gets), healthInst, fabricLink (+enriched lldpAdjEp/cdpAdjEp and their lldpInst/lldpIf/ cdpInst/cdpIf containers, v0.12.0 — same build/neighbors.py helper the boot-time builders use, so a dynamically-registered node's neighbors are queryable the identical way) cabling the new node to every spine in its site, and l1PhysIf/ethpmPhysIf port inventory (fabric uplinks + host-access ports) — so a dynamically-registered node renders identically to one seeded from topology.yaml. The reaction fires for a fabricNodeIdentP found anywhere in the POST body's validated write plan, not only when it is the top-level class (a fabricNodeIdentP nested under a parent, e.g. uni/controller, also triggers it). Pod is derived from the target site (site.pod), never hardcoded — fabricNodeIdentP/nodeidentpol DNs carry no pod of their own. POST /_sim/add-leaf shares this same enrichment.
• Multi-site playbooks push NDO schemas/templates/deploy (see §7) then per-site APIC MOs.

4. APIC — filter grammar (query-target-filter values)

• eq(<class>.<attr>,"<val>") exact match (numbers unquoted).
• ne(<class>.<attr>,"<val>") not-equal (a missing attr is treated as ≠, i.e. matches).
• wcard(<class>.<attr>,"<substr>") substring/wildcard (commonly on .dn).
• gt|lt|ge|le(<class>.<attr>,"<val>") compare — numeric when both sides parse as numbers (e.g. gt(fabricNode.id,"200")), else lexical.
• bw(<class>.<attr>,"<lo>","<hi>") inclusive range.
• and(<c1>,<c2>,...), or(<c1>,<c2>,...) compose. Nesting allowed. Zero-argument and()/or() are rejected (not "match everything" / "match nothing").
• query-target=subtree scopes the match set to root+descendants FIRST, then applies query-target-filter to every scoped MO (root and descendants alike) — a filter on an attribute only descendants carry (e.g. faultInst.severity under a fabricNode root) still reaches matching descendants; it does not pre-filter the root out of the scope before expansion.
• A malformed expression (unknown operator, truncated call, trailing tokens after a complete expression, e.g. two comma-joined filters or an unbalanced trailing )) yields a 400 APIC error envelope (code="107"), never a 500.
• Examples seen verbatim: eq(fabricNode.role,"spine"), wcard(fvCtx.dn,"tn-Tenant1/"), and(eq(fvBD.name,"X"),wcard(fvBD.dn,"tn-T/")), or(eq(faultInst.severity,"critical"),eq(faultInst.severity,"major")), ne(fvTenant.name,"common"), gt(fabricNode.id,"200"), bw(fabricNode.id,"100","200").

5. APIC — error shapes / HTTP codes

• 200 success. 400 → ACIQueryError (also: malformed aaaLogin body, bad page params, strict-filter-parse errors). 401 → bad aaaLogin credentials ("Authentication failed: invalid username or password"). 403 → ACIAuthError — missing/unknown/expired APIC-cookie on any query/write route or on aaaRefresh ("Token was invalid (Error: Token timeout)"). Error body: {"imdata":[{"error":{"attributes":{"text":"<msg>","code":"<c>"}}}]}. The /_sim/* control-plane router and /api/aaaLogin.json/aaaLogout.json are intentionally exempt from the 403 auth gate (test tooling + the login flow itself depend on them being reachable pre-auth).
• GET /api/mo/{dn}.json on a nonexistent DN → 200 + empty envelope ({"imdata":[],"totalCount":"0"}), NOT 404 (PR-9 FEATURE 6, corrects a pre-PR-9 design choice that returned 404/ACINotFoundError here). Verified against upstream cisco.aci plugins/module_utils/aci.py's api_call(): any GET response with status != 200 is unconditionally fatal (fail_json) — there is no "404 means not-found, that's fine" special case. Every state=present module does a get_existing() GET before building its diff, so on a brand-new object that GET's DN does not exist yet; a 404 there fails the very first task of any create playbook (fatal: APIC Error 103: Unable to find the object specified). 404 is reserved for genuinely malformed requests, not absent-but-well-formed objects — matching real APIC. /api/class/* and /api/node/class/* already returned 200-empty for a query matching nothing; this brings /api/mo/* in line for the "DN itself absent" case too.
• Any unmatched /api/* path → 400 APIC error envelope, never FastAPI's {"detail":...} shape (PR-10). Real APIC never emits FastAPI's default 404 body; cisco.aci cannot parse it and surfaces it as "APIC Error None: None", status=-1. Body: {"imdata":[{"error":{"attributes":{"text":"Invalid request path: <path>","code":"400"}}}],"totalCount":"1"}. Implemented as a 404 exception-handler fallback scoped to /api/* — it only fires once every real route (including the /api/node/mo alias) has already failed to match, so it can never shadow one.

6. APIC — class catalog (102) + attributes actually read

Group by concern; every listed attribute is read by some plugin/router — include them. (Header count corrected from a stale "63" to the actual number of distinct classes catalogued below, verified by direct count — see PR-3b-batch1. ✅ marks classes seeded by PR-3b-batch1 (previously catalogued here but never built, so their class queries returned empty and the depending autoACI plugins rendered nothing); 🆕 marks classes seeded by PR-3b-batch2/3 (same gap, closed in this batch); everything else was already built pre-batch-1.

Batch-2/3 changelog note (this revision):

• vpcRsMbrIfs → corrected to pcRsMbrIfs. The catalogued name was wrong: autoACI's vpc_status.py actually queries pcRsMbrIfs (the real ACI class for a port-channel member-port relation, child of pcAggrIf, RN rsmbrIfs-[{ifDn}]), never vpcRsMbrIfs — verified read-only against the plugin source before building. Built as pcRsMbrIfs in build/fabric.py; see docs/DESIGN.md "Batch-2" section.
• infraNodeIdentP → removed from this catalog, NOT built. No autoACI plugin/router references it at all (verified: a fabric-wide grep across ~/autoACI/backend/plugins/*.py for infraNodeIdentP returns zero matches — unlike fabricNodeIdentP, which the Fabric Build write-path reaction genuinely needs). Real ACI's infraNodeIdentP is a node provisioning-policy object (uni/infra/nodep-{id}, part of interface selector/AEP scoping for a specific node), a materially different concept from fabricNodeIdentP's Fabric Membership node registration (uni/controller/nodeidentpol/nodep-{id}) — the two are easy to confuse by name alone. Building an infraNodeIdentP that mirrors fabricNodeIdentP's semantics (as an earlier draft of this catalog implied) would be a faithfulness regression: a wrong object with a plausible-looking name, satisfying no real consumer. Decision: leave it out of scope entirely rather than build a wrong object.

Fabric/topology: fabricNode(id,name,role∈{spine,leaf,controller},model,serial,version,adSt,fabricSt,dn) · fabricLink(dn contains /lnk-{n1port}-to-{n2port}/, n1,n2,operSt,operSpeed,linkType) · topSystem(dn,fabricDomain,version,role,state,address/oobMgmtAddr) · fabricHealthTotal(cur) · healthInst(cur,min,max,prev) · vpcDom(id,dn,peerSt) · vpcIf(dn,name,operSt) · pcAggrIf🆕(dn,name,id,operSt) · pcRsMbrIfs🆕(tDn,parentSKey) · infraWiNode🆕(health,state) · firmwareCtrlrRunning🆕(version,node) — PR-9, one per controller at {ctrl_dn}/ctrlrfwstatuscont/ctrlrrunning.

Mgmt tenant — OOB management (OOB-gateway PR): real APIC models each node's OOB management address + default gateway in the special mgmt tenant, never on topSystem itself (topSystem.oobMgmtAddr carries only the address — see above). Prior to this PR, aci-sim init's wizard collected an OOB gateway per site but discarded it entirely (no schema field, no MO). build/mgmt.py now builds the minimal faithful scaffolding, one tree per site: fvTenant(name="mgmt", dn=uni/tn-mgmt) → mgmtMgmtP(name="default", dn=uni/tn-mgmt/mgmtp-default) → mgmtOoB(name="default", dn=uni/tn-mgmt/mgmtp-default/oob-default) → one mgmtRsOoBStNode(tDn,addr,gw) per node — switches AND controllers — at {oob-default dn}/rsooBStNode-[topology/pod-{p}/node-{id}], where tDn=topology/pod-{p}/node-{id}, addr=<node's OOB IP>/<mask> (same oob_ip(pod,node_id) address topSystem.oobMgmtAddr uses; mask from fabric.oob_subnet if set, else /24 — see build/mgmt.py docstring for why not fabric.oob_pool's /16), and gw=site.oob_gateway (empty string if unset — never invented/derived). No other mgmt-tenant children (mgmtInB, mgmtRsOoBCtx, mgmtInstP, ...) are built — no autoACI/aci-py chain audited for this sim reads them; same scope judgment as fabric.inb_subnet's store-only status (README §6c).

Faults: faultInst(dn,severity∈{critical,major,minor,warning},code,lc,type,subject,descr,created,lastTransition). Fault DNs live under node-local shards; node-scoped query via /api/node/class/{nodeDn}/faultInst.json.

Interfaces: l1PhysIf(id,adminSt,descr,mtu,mode) · ethpmPhysIf(dn has phys-[eth{s}/{p}],operSt,operSpeed,usage,lastLinkStChg,resetCtr) · ethpmFcot🆕(typeName,guiName,vendorName,vendorSn,actualType). PR-19: the ISN/IPN spine uplink l1PhysIf.mtu is now isn.mtu-driven (default 9150) instead of the general fabric 9216 hardcode every other port still uses.

Neighbors/underlay: lldpAdjEp(dn,sysName,mgmtIp,portIdV,portIdT,chassisIdT,chassisIdV,sysDesc,capability,id,ttl) · cdpAdjEp(dn,sysName,mgmtIp,devId,portId,platId,ver,cap) · lldpInst🆕(dn,adminSt,name,holdTime,initDelayTime,txFreq,ctrl,optTlvSel) · lldpIf🆕(dn has if-[eth{s}/{p}],id,adminRxSt,adminTxSt,operRxSt,operTxSt,mac,portDesc,portVlan,sysDesc,wiring) · cdpInst🆕(dn,adminSt,name,holdIntvl,txFreq,ver,ctrl) · cdpIf🆕(dn has if-[eth{s}/{p}],id,adminSt,operSt) · isisAdjEp(dn,operSt,sysId,lastTrans,numAdjTrans) · isisDom · ospfAdjEp(dn,operSt,id,peerIp/addr,nbrId,area) · ospfIf✅(name,area,state,helloIntvl,deadIntvl) · arpAdjEp✅(ip,mac,ifId,physIfId,operSt). LLDP/CDP fidelity (v0.12.0): lldpAdjEp/cdpAdjEp are now enriched with real-APIC-shaped fields (portIdV/portId carry the NEIGHBOR's own port; chassisIdV is a deterministic per-node MAC, see build/neighbors.py:node_mac; sysDesc/platId/ver describe the neighbor's model+version, or "Cisco APIC"/APIC-SERVER-M3 for a controller neighbor) — additive only, pre-existing sysName/ mgmtIp are unchanged. lldpInst/cdpInst/lldpIf/cdpIf are newly materialized containers (one inst per switch node with any adjacency, one *If per adjacency-bearing local port) — this also fixes a bug where a deep-root subtree query (GET .../sys/lldp/inst.json?query-target=subtree& target-subtree-class=lldpAdjEp) returned totalCount=0 because the root DN had no MO of its own. aci-sim lldp (CLI) prints a show lldp neighbors-style table from these fields (--cdp for CDP, --json for machine-readable output). PR-19: ospfIf.area/ospfAdjEp.area are now isn.ospf_area-driven (default "0.0.0.0") instead of a hardcoded literal. PR-20: ospfIf.helloIntvl/deadIntvl are new, driven by isn.ospf_hello/isn.ospf_dead (defaults 10/40, real ACI defaults) — previously not carried on this MO at all.

Overlay/BGP: bgpInst(dn,asn) · bgpPeer(dn,asn,addr,type,peerRole) · bgpPeerEntry(dn,addr,operSt∈{established,...},rtrId,lastFlapTs,connEst,connDrop,type) · bgpPeerAfEntry(dn,type/afId,acceptedPaths,pfxSent,tblVer) · bgpVpnRoute🆕(pfx,rd) · bgpPath🆕(nh,asPath,localPref,metric,origin,type). For ISN: each spine /sys/bgp/inst subtree must contain bgpPeer entries whose addr is a /32 and whose ASN ≠ the local fabric ASN (autoACI infers the inter-site EVPN cloud from this).

COOP/EPM: coopPol,coopInst(operSt) · epmMacEp(addr,ifId,flags,createTs,encap) · epmIpEp(addr,ifId,flags,createTs).

Routing tables/control: uribv4Route✅,uribv4Nexthop✅ · rtctrlProfile✅,rtctrlCtxP✅,rtctrlSubjP✅,rtctrlMatchRtDest✅,rtctrlSetComm✅,rtctrlSetPref✅.

Tenant (control): fvTenant(name,descr,dn) · fvCtx(name,pcEnfPref,bdEnforcedEnable,ipDataPlaneLearning,pcEnfDir,pcTag,scope) · fvBD(name,arpFlood,unicastRoute,ipLearning,unkMacUcastAct,unkMcastAct,multiDstPktAct,epMoveDetectMode,limitIpLearnToSubnets,mtu,mac,intersiteBumTrafficAllow,type) · PR-20: fvBD.mac now reflects bd.mac (per-BD) falling back to fabric.default_bd_mac (fabric-wide, default "00:22:BD:F8:19:FF" — the exact literal already hardcoded here pre-PR-20, so unset topology.yaml fields produce byte-identical output). fvSubnet(ip,scope) · fvAp(name) · fvAEPg(name,prefGrMemb,floodOnEncap,pcEnfPref,isAttrBasedEPg,pcTag) · fvCEp(mac,ip,encap,fabricPathDn) · fvIp(addr) · fvIfConn(dn has tn-/ap-/epg-, encap) · fvEpP🆕(epgPKey,pcTag,scopeId). Rels: fvRsBd(tnFvBDName) · fvRsCtx(tnFvCtxName) · fvRsBDToOut(tnL3extOutName) · fvRsDomAtt(tDn,instrImedcy) · fvRsPathAtt✅(tDn,encap,mode,instrImedcy) · fvRsCons(tnVzBrCPName) · fvRsProv(tnVzBrCPName).

Contracts: vzBrCP(name,scope,prio,targetDscp) · vzSubj(name,revFltPorts) · vzFilter(name) · vzEntry(name,etherT,prot,dFromPort,dToPort,sFromPort,sToPort,stateful) · vzRsSubjFiltAtt(tnVzFilterName) · vzRsSubjGraphAtt✅ · actrlRule🆕(scopeId,sPcTag,dPcTag,fltId,action,direction,prio,ctrctName,operSt).

L3Out (control): l3extOut(name,enforceRtctrl) · l3extLNodeP(name) · l3extRsNodeL3OutAtt(tDn,rtrId) · l3extLIfP(name) · l3extRsPathL3OutAtt(tDn,encap,addr,ifInstT) · l3extInstP(name,prefGrMemb) · l3extSubnet(ip,scope) · l3extRsL3DomAtt(tDn) · l3extRsEctx(tnFvCtxName,tDn) · l3extMember✅(side,addr) · bgpPeerP(addr,peerCtrl,keepAliveIntvl,holdIntvl) · bgpAsP(asn) · bgpExtP · ospfExtP✅ · ipRouteP✅(ip,pref) · ipNexthopP✅(nhAddr). PR-20: bgpPeerP.keepAliveIntvl/holdIntvl are new, driven by l3out.csw_peer.keepalive/.hold (defaults 60/180, real ACI defaults) — previously not carried on this MO at all.

Access policy: infraAttEntityP(AAEP,name) · infraAccPortGrp,infraAccBndlGrp✅(name,lagT) · infraAccPortP✅(name) · infraHPortS✅(name,type) · infraPortBlk✅(fromPort,toPort,fromCard) · infraRsAttEntP(tDn) · infraRsAccBaseGrp✅(tDn) · infraRsDomP(tDn) · infraRsVlanNs(tDn) · physDomP(name) · l3extDomP(name) · fvnsVlanInstP(name,allocMode) · fvnsEncapBlk(from,to) · vmmDomP🆕(name) · vmmCtrlrP🆕(name,hostOrIp,rootContName,dvsName,dvsVersion) · vmmUsrAccP🆕(name) — PR-19, Tier-2 access.vmm_domains[]; vmmCtrlrP/vmmUsrAccP only emitted when vcenter_ip is set. Pure addition — no existing plugin/production-chain reads these (see docs/DESIGN.md's PR-19 section for the verified bind_epg_to_vmm_domain DN-string-only finding).

Infra write targets (Fabric Build): fabricNodeIdentP🆕(nodep-{id},serial,nodeId,name,role) · infraInfra,infraAttEntityP, VLAN pools/AAEPs. (infraNodeIdentP intentionally removed from this catalog — see the batch-2/3 changelog note above.)

Capacity/backup: eqptcapacityPolUsage5min(polUsage,polUsageCap,polUsageCum,polUsageCapCum) · configExportP(name) · configJob(operSt,executeTime).

7. NDO / MSO contract

• POST /api/v1/auth/login {"userName","userPasswd","domain":"local"} → {"token":...} (Bearer header after). Deliberately lenient: accepts ANY credential and never validates the returned token on subsequent requests (client-compat for cisco.mso/aci-py, which expect a login to just work). This is unchanged by the admin-account wizard (§1) — NDO shares the APIC admin account by default but is never actually checked against it.
• GET /api/v1/platform/version → {"version":"4.2.2"}.
• GET /mso/api/v1/sites → {"sites":[{id,name,platform,urls[]}]}. name is the topology's fabric_name (e.g. "LAB1-IT-ACI"), NOT the short internal site name ("LAB1") — PR-10, verified against a real-gear cisco.mso.mso_tenant run that rejected the short form ("Site 'LAB1-IT-ACI' is not a valid site name" when only "LAB1" was exposed). Internal site-id joins (tenant/schema site associations) key off the topology's short name regardless of what name reports here.
• GET /mso/api/v1/tenants (also GET /api/v1/tenants — PR-10, backs cisco.mso.ndo_template's lookup_tenant() prereq lookup, same data) → {"tenants":[{id,name,displayName,siteAssociations:[{siteId}]}]}.
• GET /mso/api/v1/schemas → {"schemas":[{id,displayName,name,templates:[{name}]}]}.
• GET /mso/api/v1/schemas/list-identity (PR-10) → {"schemas":[{id,displayName}]} — lightweight enumeration every cisco.mso schema module calls first to resolve a schema displayName → id (verified against ansible-mso's plugins/module_utils/mso.py lookup_schema(), which calls query_objs("schemas/list-identity", key="schemas", displayName=schema)). Must be declared before the parameterized /schemas/{id} route below, or "list-identity" gets matched as a schema id instead.
• GET /mso/api/v1/schemas/{id} → full schema; template shape: templates[].{name,templateType,vrfs[],bds[],anps[].epgs[],contracts[],filters[],externalEpgs[]} and top-level sites[].{templateName,siteId}.
  • vrf: {name,displayName,vrfRef:"/vrfs/NAME",vzAnyEnabled,ipDataPlaneLearning}
  • bd: {name,vrfRef:"/vrfs/NAME",subnets:[{ip}],l2Stretch,intersiteBumTraffic,l2UnknownUnicast,arpFlood,unicastRouting,epMoveDetectMode,dhcpLabels:[{ref:UUID}]}
  • epg: {name,bdRef:"/bds/NAME",preferredGroup,proxyArp,uSegEpg,intraEpg,contractRelationships:[{relationshipType,contractRef:"/contracts/NAME"}]}
  • contract: {name,scope,filterRelationships:[{filterRef:"/filters/NAME"}]} filter: {name,entries:[{name,ipProtocol,dFromPort,dToPort,etherType}]}
  • externalEpg: {name,vrfRef,l3outRef:"/l3outs/NAME",type,subnets:[{ip}]}
• GET /mso/api/v1/sites/fabric-connectivity → {"sites":[{id/siteId,status,connectivityStatus}]} (or list).
• GET /mso/api/v1/schemas/{id}/policy-states → [{status,drift}] or {policyStates:[...]}.
• GET /mso/api/v1/templates/summaries → [{templateId,templateName,templateType}] (tenantPolicy carries DHCP; templateName required — PR-13 — since ansible-mso's MSOTemplate resolves templates by name+type).
• GET /mso/api/v1/templates/{id} → {tenantPolicyTemplate:{template:{dhcpRelayPolicies:[{uuid,name}],dhcpOptionPolicies:[{uuid,name}]}}}.
• Template writes (PR-13): POST /templates (create — payload {displayName,templateType,<typeContainer>:{template:{...},sites:[{siteId}]}}, e.g. tenantPolicyTemplate), PATCH /templates/{id} (JSON-Patch ops, e.g. add /tenantPolicyTemplate/template/dhcpRelayPolicies/-), DELETE /templates/{id}. Both bare (/api/v1/...) and /mso-prefixed (/mso/api/v1/...) forms are backed by the same store — see §7c.
• GET /templates/objects?type={dhcpRelay|dhcpOption|epg|externalEpg}&{uuid=...|name=...} (both prefixes) — cross-template object lookup; dhcpRelay/dhcpOption search every tenant-policy template's policy lists, epg/externalEpg search every schema template's anps[].epgs[]/externalEpgs[]. Returns a list when only type (or type+name) is given, a single object (or {}) when uuid is given.
• GET /mso/api/v1/schemas/service-node-types (also bare) → {"serviceNodeTypes":[{id,displayName}]} (Firewall/Load Balancer/Other).
• GET /api/v1/audit-records?count=N (fallback /mso/api/v1/audit-records) → {auditRecords:[{timestamp,user,action,description,details}]} (or records/imdata/list).
• Writes: POST /mso/api/v1/schemas, POST /mso/api/v1/deploy → accept + store; return an id/status. Cross-plane rule: NDO tenants/VRFs/BDs must match APIC MIT names.
• Errors: 401 → NDOAuthError; else propagate. Router returns {"detail":...}.

7a. NDO schema write round-trip (PR-11)

The multi-site (MS) aci-ansible playbooks create a per-tenant-region schema (<tenant>-<region>, e.g. "MS-TN1-LAB0") during create_tenant's MSO play, then PATCH it from every subsequent playbook (create_bd, create_application, ...). Verified against ansible-mso's plugins/module_utils/{mso,schema}.py and a real multi-site E2E run against ACI hardware.

• Sequence: GET schemas/list-identity (displayName→id) → GET schemas/{id} (full doc) → PATCH schemas/{id} with a JSON-Patch-shaped op list [{"op":"add"/"replace"/"remove","path":...,"value":...}]. POST /mso/api/v1/schemas creates a schema (optionally already carrying its first template — mso_schema_template.py's "schema doesn't exist yet" branch); PATCH applies ops against the stored doc and returns the updated doc. Implemented in aci_sim/ndo/patch.py (apply_json_patch), wired into aci_sim/ndo/app.py's create_schema/patch_schema routes.

• Path addressing — three conventions cisco.mso modules use, all supported:

  1. Standard RFC 6902: numeric index, or "-" to append.
  2. Named-segment lookup against a name/displayName field — most template-level objects (bds/anps/epgs/contracts/filters/externalEpgs/vrfs), e.g. /templates/LAB1/bds/bd-App1_LAB1.
  3. A synthetic composite key "{siteId}-{templateName}" unique to the top-level sites[] array — every mso_schema_site_* module builds this literally (site_template = "{0}-{1}".format(site_id, template)), e.g. /sites/1-LAB1/bds/-.
  4. A *Ref-name lookup for site-local child objects, which carry no name field of their own — only a bdRef/vrfRef/etc string pointing back at the template object — yet are still addressed by that object's bare name: /sites/1-LAB1/bds/bd-App1_LAB1/subnets/-.

• Collection-default normalization: real NDO always serves back every collection key (vrfs/bds/anps/contracts/filters/externalEpgs/intersiteL3outs/serviceGraphs, and nested subnets/epgs/contractRelationships/...) as [] even when a client's create/add payload omitted them. normalize_template()/normalize_site() backfill these on every create and every PATCH — a missing key is a hard client-side crash ('NoneType' object is not iterable, bare KeyError), not a 4xx, so this has to be done proactively rather than reactively.

• *Ref string normalization: several write payloads (e.g. mso_schema_site_bd.py's bdRef=dict(schemaId=...,templateName=...,bdName=...)) send a dict form of a *Ref field, but real NDO stores/serves it as the canonical string /schemas/{schemaId}/templates/{templateName}/{category}/{name} — confirmed because a sibling module (custom_mso_schema_site_bd_subnet.py) does bd_ref_string in [v.get('bdRef') for v in ...] and ', '.join(...) on the stored values; a dict there crashes with TypeError: sequence item 0: expected str instance, dict found. apply_json_patch stringifies bdRef/vrfRef/l3outRef/filterRef/contractRef/anpRef/serviceGraphRef dicts on every add/replace op.

• ND user-class fallback: GET /api/config/class/remoteusers / /localusers → {"items":[{"spec":{"loginID",...,"id"|"userID"}}]}. cisco.mso.mso_tenant's lookup_users()/lookup_remote_users() query the modern /nexus/infra/api/aaa/v4/* routes first and fall back to these legacy routes when both come back empty; a 404 here (no route at all) aborts with "ND Error: Unknown error no error code in decoded payload" since the error body has neither code nor messages.

• Bare GET /api/v1/sites (PR-11) — cisco.mso.ndo_template's TenantPol prereq lookup hits this un-prefixed path; same data as /mso/api/v1/sites.

• PUT/POST /mso/api/v1/tenants{,/{id}} — mso_tenant's create-vs-update branch: every tenant this sim seeds already exists in GET /mso/api/v1/tenants, so a real run always takes the PUT .../tenants/{id} (update) path.

• Schema-template deploy: GET schemas/{id}/validate (legacy + ndo_schema_template_deploy, discarded return value, only status matters), GET execute|status/schema/{id}/template/{name} (legacy mso_schema_template_deploy), POST /mso/api/v1/task {schemaId,templateName,isRedeploy} (ndo_schema_template_deploy — the module aci-ansible's mso-model role actually invokes; confirmed against the collection installed on real ACI hardware, which differs from ansible-mso's master-branch module source).

• Site-local ANP/EPG auto-mirroring + self-referencing anpRef/epgRef (PR-12). Two compounding gaps, both required to close bind_epg_to_static_port:

  1. Template-level self-refs. Real NDO stores a self-referencing anpRef string on every template-level ANP object itself (and epgRef on every EPG) — confirmed because ansible-mso's mso_schema_template_anp.py/_anp_epg.py explicitly strip it client-side before an idempotency comparison (if "anpRef" in mso.previous: del mso.previous["anpRef"]) — dead code unless the server actually sends one back. MSOSchema.set_site_anp()/set_site_anp_epg() (ansible-mso's module_utils/schema.py) key their site-local lookup off exactly this field (template_anp.details.get("anpRef")); without it, the lookup compares every site-anp's anpRef against None and never matches. normalize_template() (aci_sim/ndo/patch.py) now backfills anpRef/epgRef on every anps[]/epgs[] entry it normalizes (/schemas/{id}/templates/{t}/anps/{a} and /schemas/{id}/templates/{t}/anps/{a}/epgs/{e} respectively), and takes an optional schema_id param to build them; build_ndo_model() (aci_sim/ndo/model.py) calls it at boot too, so a topology tenant that ships with ANPs/EPGs already configured doesn't skip this.
  2. Site-local mirroring. Real NDO 4.x auto-populates a schema's site-local sites[].anps[].epgs[] the moment a template-level ANP/EPG is added to a template that already has a site attached (mso_schema_site.py already ran in create_tenant's flow, per PR-11). apply_json_patch replicates this: an add /templates/{t}/anps/- op auto-creates a matching {anpRef, epgs:[]} entry in every sites[] row whose templateName == t; an add /templates/{t}/anps/{a}/epgs/- op auto-creates a matching full-shaped site-EPG {epgRef, subnets:[], staticPorts:[], staticLeafs:[], domainAssociations:[]} entry under that mirrored site-anp. build_ndo_model() performs the same mirroring at boot for topology-seeded schemas. Both are idempotent (safe on playbook retries). The full child-collection shape is mandatory: every sibling mso_schema_site_anp_epg_* module reads its own array with a bare subscript (not .get()), so any missing key is a hard KeyError client-side — mso_schema_site_anp_epg_domain.py bare-subscripts domainAssociations (domains = [dom.get("dn") for dom in ...["epgs"][epg_idx]["domainAssociations"]]), _staticleaf reads staticLeafs, _staticport reads staticPorts, _subnet reads subnets. A real hardware MS-TN1 run regressed on bind_epg_to_physical_domain/_vmm_domain with KeyError: 'domainAssociations' when the mirrored site-EPG shipped without it (pre-PR-12 those binds passed only because no site-EPG existed at all, so the module took a non-crashing branch). Single source of truth for the shape is SITE_OBJECT_DEFAULTS["epgs"], consumed by both _new_site_epg() (mirror path) and normalize_site() (backfill path).

  Both *Ref strings use NDO's canonical form — anpRef: /schemas/{id}/templates/{t}/anps/{a} (_REF_NAME_FIELDS); epgRef uniquely nests two name segments, /schemas/{id}/templates/{t}/anps/{a}/epgs/{e} (confirmed against ansible-mso's module_utils/mso.py epg_ref() — handled by a dedicated _stringify_refs branch since the generic single-category table only fits one name field). _REF_LOOKUP_KEYS also gained epgRef so a site-epg (ref-only, no name of its own) resolves by its bare EPG name the same way site-local bds/anps already did (PR-11).

  Without either fix, mso_schema_site_anp_epg_staticport.py's own "create site anp/epg if missing" fallback fires instead (its own code comment: "Coverage misses this two conditionals when testing on 4.x and above" — i.e. it's dead code on real hardware) and ultimately crashes with 'NoneType' object has no attribute 'details' — confirmed on a real MS-TN1 bind_epg_to_static_port run on ACI hardware before this fix (schema=MS-TN1-LAB0, anp=app-Web_LAB1, epg=epg-web, site=LAB1-IT-ACI, static vpc port ipg-vpc-LegacySW01 vlan-100), now resolved end-to-end.

7c. Tenant-policy-template DHCP surface + schema serviceGraphs (PR-13)

Closes the last two NDO write-surface gaps blocking the MS suite's DHCP and service-graph tasks. Verified against ansible-mso's plugins/modules/{ndo_template,ndo_dhcp_relay_policy,ndo_schema_template_bd_dhcp_policy}.py, plugins/module_utils/{mso,template}.py, the mso-model role's library/custom_mso_schema_service_graph.py, and real multi-site E2E runs against ACI hardware.

• Bare vs /mso-prefixed split, and why it matters for templates. ansible-mso's MSOModule.request() builds its URL differently depending on connection mode: tasks using the persistent ansible.netcommon.httpapi connection (ansible_network_os: cisco.nd.nd) route through NDO_API_VERSION_PATH_FORMAT = "/mso/api/{v}/{path}"; tasks carrying delegate_to: localhost (no persistent httpapi socket) fall through MSOModule's direct-HTTP branch, which never adds the /mso prefix at all — self.url = "{0}api/{1}/{2}".format(base_uri, api_version, path). prereq_tenantpol.yml's cisco.mso.ndo_template task uses delegate_to: localhost, so it hits GET/POST https://host/api/v1/templates* (BARE) while create_dhcp_relay's cisco.mso.ndo_dhcp_relay_policy and bind_dhcp_relay_to_bd's cisco.mso.ndo_schema_template_bd_dhcp_policy (no delegate_to) hit the /mso-prefixed form. Both forms are registered against the SAME mutable template store (aci_sim/ndo/app.py's _get_template_summaries/_create_template/_patch_template/_get_template_objects, looped over ("/mso/api/v1", "/api/v1")), matching the existing /api/v1/tenants ↔ /mso/api/v1/tenants / /api/v1/sites ↔ /mso/api/v1/sites pattern PR-10/PR-11 established for the identical delegate_to split.
• Template create/lookup sequence. ndo_template's MSOTemplate.__init__ first queries templates/summaries?templateName=...&templateType=... (name+type filter; schemaName/schemaId kwargs are None and skipped by query_objs()) — every summary entry therefore needs a templateName field, not just templateId/templateType (the boot-seeded tenantPolicy template summary was retrofitted with one). If nothing matches, it POSTs {displayName, templateType, tenantPolicyTemplate:{template:{tenantId}, sites:[{siteId}]}} to templates (no /summaries suffix) — the sim assigns a templateId, stores the full doc, and mirrors a summary entry so the very next templates/summaries lookup (by any caller, either path prefix) resolves it.
• DHCP relay policy add + uuid backfill. ndo_dhcp_relay_policy's add PATCHes add /tenantPolicyTemplate/template/dhcpRelayPolicies/- with {name, providers, description?} — no uuid (real NDO assigns one server-side). A provider's epgRef is the target schema-template EPG's uuid (MSOSchema.set_template_anp_epg().details.get("uuid")) — schema-template EPGs/externalEpgs never carried a uuid field before this PR; normalize_template() now backfills a stable one (_normalize_object's epgs/externalEpgs branches). ndo_schema_template_bd_dhcp_policy (bind_dhcp_relay_to_bd) resolves a relay/option policy's uuid via GET templates/objects?type={dhcpRelay|dhcpOption}&name=..., requiring both a tenantId (matched client-side against the policy-owning template) and a non-empty uuid on the returned entry, or it fail_jsons — the sim's _patch_template backfills a stable uuid on every dhcpRelayPolicies/dhcpOptionPolicies entry that lacks one. The same templates/objects route also serves type=epg/type=externalEpg queries (searching every schema template's anps[].epgs[]/externalEpgs[]), used by ndo_dhcp_relay_policy's own uuid→name resolution on query/present.
• Site-level serviceGraphs + full-detail GET /schemas. The mso-model role's "Create service graph" task uses custom_mso_schema_service_graph.py, a pre-MSOTemplate/MSOSchema community module (version_added: '2.8') that bare-subscripts straight into the RAW GET /schemas list response: mso.get_obj('schemas', displayName=schema) then schema_obj.get('templates')[idx]['serviceGraphs'] and, once a site-local device binding step runs, schema_obj.get('sites')[site_idx]['serviceGraphs']. The template-level bare-subscript was already covered (PR-11's TEMPLATE_COLLECTION_KEYS), but (a) the sim's GET /mso/api/v1/schemas previously returned only a trimmed {id,displayName,name,templates:[{name}]} summary — insufficient for this module's bare-subscript pattern, which needs the full nested doc (bds/anps/serviceGraphs/sites) — and (b) the SITE-level serviceGraphs key was never backfilled at all. Both fixed: GET /schemas now returns full schema detail per entry (real NDO's plain list endpoint already does this — it's precisely why the lighter schemas/list-identity endpoint exists as a separate optimization); SITE_TOP_LEVEL_DEFAULTS (aci_sim/ndo/patch.py) backfills serviceGraphs (and contracts, see below) as top-level keys on every schema sites[] entry via normalize_site(). The module also needs GET schemas/service-node-types (Firewall/Load Balancer/Other → stable id) and a tenantId field on the schema template itself (used on its "service graph already exists, add a node" branch) — both added.
• Site-local contracts mirroring (deeper layer, found chasing GAP 2 to green on real ACI hardware). Once the serviceGraphs KeyError was fixed, a real hardware MS-TN2 create_tenant pass-2 run (-e automate_contract_graph=true -e automate_site_redirect=true) progressed to the mso-model role's raw cisco.mso.mso_rest-driven "Atomic PATCH — bind service-graph redirect on ALL fabrics in one request" task, which PATCHes add /sites/{siteId}-{template}/contracts/{contract}/serviceGraphRelationship — addressing a SITE-LOCAL contract by bare name, mirroring the same addressing convention site-local bds/anps already use. The sim never mirrored template-level contract adds into sites[].contracts[] at all (unlike anps/epgs, mirrored since PR-12), so apply_json_patch's _find_by_name raised PatchError: path segment 'con-Firewall_LAB0' not found in list — confirmed verbatim on the real run. _mirror_template_contract_to_sites() (PATCH-time, parallel to _mirror_template_anp_to_sites) and an equivalent boot-time mirror in build_ndo_model() close this: an add /templates/{t}/contracts/- op (or a topology-seeded template that already has contracts) now auto-creates a matching {contractRef} entry in every sites[] row whose templateName == t.
• Verified on real ACI hardware end-to-end: MS-TN1 create_dhcp_relay (08) and bind_dhcp_relay_to_bd (09) both reach failed=0; MS-TN2's identical DHCP chain (08/09) also failed=0; MS-TN2 create_tenant pass-2 (01b, -e automate_contract_graph=true -e automate_site_redirect=true) reaches failed=0 — including the atomic per-fabric service-graph redirect PATCH. No regression observed on MS-TN1/MS-TN2's already-green tasks (01-07, 10, 01a) or a SF-suite spot-check (create_tenant, create_dhcp_relay) re-run on the same sandbox.

7d. Site-local BD auto-mirroring for aci-py (PR-15)

Closes a schema-PATCH 400 mid create_tenant/create_bd, found running aci-py (a pure-Python Ansible-to-ACI compiler, distinct from the ansible-mso/cisco.mso collection §7a-7c document) against the sandbox on real ACI hardware. Same family of gap as PR-12's ANP/EPG mirroring and PR-13's contract mirroring — this closes the missing BD sibling.

• Why mso_schema_site_bd always sends replace, never add. aci-py's mso_schema_site_bd shim (mirroring ansible-mso's mso_schema_site_bd.py) PATCHes a site-local BD shadow with op: replace unconditionally — its own docstring/comment documents why: real NDO 4.x auto-creates the site BDDelta shadow the instant a template-level BD is added to a template that already has a site attached, so by the time the site-BD module runs the shadow already exists and a fresh add would 409 ("Multiple BDDelta entries") on real hardware; the module does a GET-then-replace instead.
• The gap. The sim mirrored template-level ANP/EPG adds into sites[].anps[].epgs[] (PR-12) and contract adds into sites[].contracts[] (PR-13) but never mirrored template-level BD adds into sites[].bds[] at all. So the very first replace /sites/{siteId}-{t}/bds/{bd} against a schema that had only ever seen the template-level add /templates/{t}/bds/- hit _find_by_name's "not found" branch: PatchError: replace: 'bd-FW_LAB0' not found at '/sites/1-LAB1-LAB2/bds/bd-FW_LAB0' — confirmed verbatim against a real hardware aci-py create_tenant/create_bd run (MS-TN2) before this fix.
• Fix. _mirror_template_bd_to_sites() (aci_sim/ndo/patch.py, PATCH-time, parallel to _mirror_template_anp_to_sites/_mirror_template_contract_to_sites): an add /templates/{t}/bds/- op now auto-creates a matching site-local BD shadow (_new_site_bd(): {bdRef, hostBasedRouting: False, subnets: []} — the full child-collection shape mso_schema_site_bd_subnet.py bare-subscripts) in every sites[] row whose templateName == t. build_ndo_model() (aci_sim/ndo/model.py) performs the equivalent mirroring at boot, so a topology.yaml tenant that ships with BDs already configured also starts with the site shadow pre-mirrored (matching the same boot-time treatment PR-12/PR-13 gave ANPs/EPGs/contracts). Idempotent (safe on playbook/driver retries) — _find_by_name skips a site that already carries the bdRef.
• Verified on real ACI hardware end-to-end: aci-py's scripts/live_chain.py driver against environments/lab-multisite-sim — MS-TN2 now reaches 13/13 steps rc=0 (was 9 ok / 4 fail before this fix: create_tenant pass1, create_bd, create_tenant pass2, and migrate_existing_vlan_gateway all 400'd on exactly this replace: 'bd-*' not found error); MS-TN1 stays 11/11 rc=0 (1 skip — no set_primary_fw_state var file for TN1's combo — no regression).

7e. Site-local BD mirror-vs-site-module dedup (PR-16)

Closes a site-local BD duplication left behind by PR-15's mirror, found running the Acme App1-Net tenant's create_tenant/create_bd playbooks against a real NDO schema on ACI hardware (schema App1-Net-LAB0).

• The symptom. After create_tenant (whose template-BD add fires _mirror_template_bd_to_sites, PR-15) and create_bd (whose cisco.mso.mso_schema_site_bd/custom_mso_schema_site_bd_subnet tasks PATCH the site-local shadow), sites[0].bds on the live schema carried two entries for the same template BD App1-Net_VLAN10: one empty mirror (bdRef=".../templates/LAB1/bds/App1-Net_VLAN10", subnets=[]) and one carrying the real subnet (10.10.10.1/24). Real NDO has exactly one site-BD row per template BD.
• Root cause #1 — the append path skipped dedup entirely. apply_json_patch's op: add handling has three sub-branches keyed on the last path token: "-" (append), a numeric index (insert), or a name (resolved via _find_by_name, which already deduped named-segment adds). Only the named-segment branch deduped. mso_schema_site_bd.py's "BD does not exist yet" branch (confirmed against the pre-existing test_patch_add_site_bd_by_composite_key, PR-11) PATCHes add /sites/{siteId}-{template}/bds/- — the append form — so it always appended unconditionally, regardless of whether the template-add mirror already created a site-local shadow for the same BD.
• Root cause #2 — _find_by_name's own ref-lookup only recognized the STRING ref form. Even where dedup was attempted (the mirror's own idempotency check, _find_by_name(site["bds"], bd_name)), it iterated each item's bdRef and matched only isinstance(ref_val, str). Several real cisco.mso write payloads send bdRef as a dict ({schemaId, templateName, bdName}, or a bare {bdName: ...} with no schema/template context) — an existing site-local entry left in that shape was invisible to any subsequent name-based lookup.
• Fix — dedup a NAMELESS shadow strictly by its single IDENTITY ref. A site-local shadow (sites[].bds/anps/epgs/contracts entry) carries no name/displayName of its own; its identity is exactly one *Ref (bds→bdRef, anps→anpRef, epgs→epgRef, contracts→contractRef, in _IDENTITY_REF_BY_COLLECTION). _bare_ref_name(ref_val) extracts the bare object name from that identity ref regardless of shape (string trailing segment, or the dict form's own name field via _REF_NAME_FIELDS), so a dict-form bdRef (a site-module payload's shape, possibly a bare {bdName: ...}) and a string-form bdRef (the mirror's canonical shape) resolve to the same bare name. _find_by_name's ref-lookup now fires only for nameless items and only over the identity-ref keys (never a property ref like vrfRef). _find_shadow_by_identity(items, value, collection) is the append-path counterpart: it dedups only a nameless value, only by the identity ref for that collection (tokens[-2]), and apply_json_patch's add+"-" branch calls it before appending — a match replaces in place (cisco.mso's GET-then-write idiom, real NDO's one-row-per-object invariant), a genuinely new shadow appends. Because the machinery is keyed by collection→identity-ref, it covers site-local ANPs/contracts too with no per-type change.
• Why identity scoping is load-bearing (regression the first cut of this PR shipped and an independent full-chain run caught). An earlier cut resolved a value's identity by iterating all _REF_LOOKUP_KEYS — including vrfRef/l3outRef. But every template BD under one L3-attached VRF shares the same vrfRef (e.g. vrf-L3_LAB0), and a template-level BD add (a NAMED object, not a shadow) was also run through the same dedup. Result: two distinct template BDs both "matched" via their shared vrfRef, so each add /templates/{T}/bds/- overwrote the previous one and every template's BDs collapsed to a single entry — the real Acme create_bd failed with "Provided BD 'bd-App2-Net_VLAN11_LAB0' does not exist. Existing BDs: bd-App3-Hst_VLAN12_LAB0" (only the last-added BD survived per template). The invariant the corrected code enforces: a named object is matched ONLY by name/displayName, never by any *Ref; ref-matching is ONLY for nameless shadows and ONLY via the ONE identity ref for that list — a property ref is a property, not an identity. Guarded by test_distinct_template_bds_sharing_vrfref_do_not_collapse and three sibling tests.
• Verified on real ACI hardware end-to-end: Acme App1-Net tenant's create_tenant.yml + create_bd.yml both failed=0 against the sim; the live NDO schema App1-Net-LAB0 shows template BD counts LAB1-LAB2=6, LAB1=14, LAB2=10 (30 total, no template collapse) and exactly one site-local BD entry per template BD in each site's bds[] (no duplicate).

8. Topology view (GET /api/topology) — exact needs

Per site autoACI issues: fabricNode, fabricLink, vpcDom, fabricHealthTotal (paged); per-node query_dn("topology/pod-{pod}/node-{id}/sys/health") → healthInst.cur; fabric-wide faultInst (severity filter) — counts per node parsed from /node-{id}/ in DN; session tables ospfAdjEp, bgpPeer, bgpPeerEntry, bgpPeerAfEntry; multi-site ISN: per spine query_dn("topology/pod-1/node-{spineId}/sys/bgp/inst", subtree=True, subtree_class="bgpPeer") → detects /32 peers with asn≠local → synthesizes an ISN cloud node + spine→ISN links. Node detail GET /api/topology/node/{id}: ethpmPhysIf,l1PhysIf (via /sys subtree), node-scoped faultInst, fvIfConn (EPGs on ports), health. pod is parsed from fabricNode.dn (pod-{N}) — do NOT assume pod-1 everywhere. Link adjacency from fabricLink.n1/n2 + DN /lnk-{p1}-to-{p2}/. Roles from fabricNode.role.

9. Plugins — 46 files, all must get believable data

Every class in §6 is read by some plugin. Control-plane plugins (tenant/bd/epg/vrf/contract/l3out/access/ capacity) read config MOs. Data-plane plugins (bgp_health, routing_state, fabric_bgp_evpn, adjacency_health, interface_status/flaps, ep_tracker, fault_summary, health_score) read operational MOs. Many do two-pass parent→child parsing and use eq/wcard filters + subtree. The generic query engine + a consistent MIT covers all of them without per-plugin code.

10. Fabric Build (mostly local; write path is dry-run-first)

Catalog/prereq-gate/common-vars/generate-vars are LOCAL to autoACI (no APIC). Real apply goes through a hidden /api/_internal/run-playbook that compiles templates via aci-py → POST /api/mo/{dn}.json (single-fabric) and/or NDO schemas+deploy (multi-site), --check (dry-run) by default. To test a playbook end-to-end: run in apply mode → sim upserts the MOs → verify via read-back. ~22 playbooks are pure ACI/NDO REST (create_/bind_/initial_fabric_/add_leaf/add_spine/provision_); the N5K/N7K SSH migration family is OUT OF SCOPE.

11. Ansible-compatibility (PR-9 — cisco.aci fidelity)

The owner's primary public use case is running Ansible cisco.aci playbooks against this simulator directly (not just autoACI). Everything below was verified read-only against upstream plugins/module_utils/aci.py (https://github.com/CiscoDevNet/ansible-aci) — the shared HTTPAPI/module base every cisco.aci.aci_* module calls into.

GET-before-write existence check (FEATURE 6, live blocker). Every state=present/state=absent module calls get_existing() (a GET) before building its diff or delete. api_call()'s response handling treats ANY status != 200 as fatal via fail_json — GET has no "404 = not found, that's fine" carve-out. So GET /api/mo/{dn}.json on a nonexistent-but- well-formed DN must be 200 {"imdata":[],"totalCount":"0"}, never 404 (§5 above) — otherwise the first task of any state=present playbook against a not-yet-created object fails immediately.

DELETE /api/mo/{dn}.json (state=absent). delete_config():

if not self.existing and not self.suppress_previous:
    return
elif not self.module.check_mode:
    self.api_call("DELETE", self.url, None, return_response=False)

The module itself is idempotent at the CLIENT level — it only ever issues DELETE after its own GET confirmed the object exists, so it never actually sends a DELETE for an already-absent DN. This sim implements the route as server-side idempotent too (200 + empty envelope whether the DN existed or not) rather than 404-on-missing: (a) it matches this codebase's existing MIT delete semantics (MITStore.upsert's status="deleted" branch is unconditional, no existence check) and (b) it's the safer default for any OTHER client that DOES call DELETE without a prior GET. An existing DN's entire subtree is removed (MITStore.delete(dn), public wrapper added in PR-9 around the pre-existing _remove_subtree helper upsert already used).

status attribute. cisco.aci's payload() never sets a status key — delete goes through the dedicated DELETE verb above, not a POST body with status:"deleted". That POST-body form is a Fabric Build / aci-py convention this sim already supported (§3) and continues to: status: "deleted" on any planned (class, attrs) node removes that DN's entire subtree (verified: MITStore.upsert already special-cased this pre-PR-9; PR-9 added regression coverage). Any other status value (including the literal string "created,modified", which real APIC/aci-py tooling can emit) is ignored and the write proceeds as a normal upsert — no special handling, no error.

annotation/ownerKey/ownerTag/nameAlias passthrough. cisco.aci's aci_annotation_spec() defaults annotation to the literal string "orchestrator:ansible" and payload() injects it (plus ownerKey/ ownerTag when set) into proposed["attributes"] for every managed object, unconditionally. name_alias is a separate per-module spec, also folded into the same attributes dict when set. None of these are special sim attributes — they round-trip because MO.attrs is a generic dict[str,str] and the write path never allowlists known attribute names; this section just documents and regression-tests that this passthrough survives POST → mo GET → class query unchanged.

Certificate signature auth (accept-mode). cisco.aci supports password-less auth via private_key; cert_auth() sets a single Cookie header per request (never touches APIC-cookie / never calls aaaLogin):

sig_dn = "uni/userext/user-{username}/usercert-{certificate_name}"
self.headers["Cookie"] = (
    "APIC-Certificate-Algorithm=v1.0; "
    f"APIC-Certificate-DN={sig_dn}; "
    "APIC-Certificate-Fingerprint=fingerprint; "
    f"APIC-Request-Signature={base64(RSA-SHA256(method+path+body))}"
)

This sim implements accept-mode: require_session() treats a request carrying all four APIC-Certificate-*/APIC-Request-Signature cookies as authenticated, for the user named in APIC-Certificate-DN, PROVIDED that user matches SIM_USERNAME — WITHOUT verifying the RSA-SHA256 signature bytes at all. A missing cookie, an unparsable APIC-Certificate-DN, or a DN naming a different user all fall through to the normal cookie-session check (which also fails for a request that never called aaaLogin), yielding the standard 403 envelope. This is a deliberate simulator trust model — see docs/DESIGN.md's "Certificate accept-mode trust model" note. SIM_CERT_STRICT env var is a documented placeholder for a future signature-verifying mode; it currently has no effect.

firmwareCtrlrRunning. Seeded per controller (build/fabric.py, alongside the existing controller topSystem) at {ctrl_dn}/ctrlrfwstatuscont/ctrlrrunning, version = site.apic_version — the same value topSystem.version already carried, so the two can never drift apart. Small, trivially-derived addition; not previously built.