package webui

import (
	"encoding/json"
	"fmt"
	"html"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

	"bee/audit/internal/app"
	"bee/audit/internal/platform"
	"bee/audit/internal/schema"
)

func renderTopoMainDiagram(hw schema.HardwareSnapshot, exportDir string) string {
	// A GPU hardware fault that needs a physical reboot (Xid 79 "fallen off
	// the bus", Xid 154 "Node Reboot Required" — see gpuNeedsPhysicalReboot)
	// isn't visible in dev.Status: the collector only sets that from PCIe
	// link-speed checks, not from SAT/kmsg results. Without this, a GPU that
	// dropped off the bus mid-test still renders green here even though the
	// Hardware Summary card is showing a critical banner for it.
	gpuHardwareFault := false
	if db, err := app.OpenComponentStatusDB(filepath.Join(exportDir, "component-status.json")); err == nil {
		if _, needsReboot := gpuNeedsPhysicalReboot(matchedRecords(db.All(), nil, []string{"pcie:gpu:"})); needsReboot {
			gpuHardwareFault = true
		}
	}

	socketIdx := buildSocketIndex(hw.CPUs)
	numCols := len(hw.CPUs)
	if numCols == 0 {
		numCols = 1
	}
	unknownCol := numCols // extra trailing column for unmatched devices

	// Group PCIe devices (GPU/NIC/RAID only — matches the mockup's node
	// types) into columns by NUMA node, falling back to the "unknown" bucket.
	type placedDevice struct {
		dev  schema.HardwarePCIeDevice
		kind string // "gpu", "nic", "raid"
		col  int
		bdf  string
	}
	var placed []placedDevice
	for _, dev := range hw.PCIeDevices {
		kind := pcieDeviceKind(dev)
		if kind == "" {
			continue
		}
		col := unknownCol
		if dev.NUMANode != nil {
			if ci, ok := socketIdx[*dev.NUMANode]; ok {
				col = ci
			}
		}
		bdf := ""
		if dev.Slot != nil {
			bdf = normalizeTopoBDF(*dev.Slot)
		} else if dev.BDF != nil {
			bdf = normalizeTopoBDF(*dev.BDF)
		}
		placed = append(placed, placedDevice{dev: dev, kind: kind, col: col, bdf: bdf})
	}

	// GPU index<->BDF map + pairwise NVLink adjacency, read from the
	// persisted techdump captured during the last audit cycle, best-effort:
	// if the dump is missing (older audit, no NVIDIA GPUs), this is simply
	// skipped. Used only to detect the cross-NUMA-bonded-pair anomaly below;
	// the pairwise links themselves are drawn in the separate NVLink
	// Topology card, since grouping same-kind/same-column devices into one
	// stacked card here leaves no single per-GPU anchor point to draw a
	// pairwise connector to or from.
	bdfToIndex, _ := readNVIDIAIndexByBDF(exportDir)
	var pairs []gpuPairLink
	if topoMatrix, err := readGPUTopologyMatrix(exportDir); err == nil {
		pairs = parseGPUPairAdjacency(topoMatrix)
	}
	gpuNUMAByIndex := map[int]*int{}
	gpuBDFByIndex := map[int]string{}
	for _, p := range placed {
		if p.kind != "gpu" || p.bdf == "" {
			continue
		}
		if idx, ok := bdfToIndex[p.bdf]; ok {
			gpuNUMAByIndex[idx] = p.dev.NUMANode
			gpuBDFByIndex[idx] = p.bdf
		}
	}
	// A bonded pair spanning two different NUMA nodes is treated as an
	// anomaly (not a neutral fact) per project decision: a bonded pair is
	// expected to sit on one NUMA node, so a cross-NUMA bond escalates both
	// GPUs' effective severity to at least Warning, regardless of their own
	// reported SAT status.
	crossNUMAWarnBDF := map[string]bool{}
	for _, pair := range pairs {
		numaA, okA := gpuNUMAByIndex[pair.GPUA]
		numaB, okB := gpuNUMAByIndex[pair.GPUB]
		if !okA || !okB || numaA == nil || numaB == nil || *numaA == *numaB {
			continue
		}
		crossNUMAWarnBDF[gpuBDFByIndex[pair.GPUA]] = true
		crossNUMAWarnBDF[gpuBDFByIndex[pair.GPUB]] = true
	}

	kindOrder := []string{"gpu", "nic", "raid"}
	kindLabel := map[string]string{"gpu": "GPU", "nic": "NIC", "raid": "RAID"}

	// Attach memory DIMMs to their CPU column too, the same way GPU/NIC/RAID
	// PCIe devices are attached via NUMANode — memory has no NUMANode field
	// in the schema, so this reads the DIMM's own Locator/Bank Locator
	// strings instead (see dimmRawNode). DIMMs that can't be confidently
	// attached fall back to the unattached "Memory" row below the diagram,
	// same as before this existed.
	memBankNodes := map[string]int{}
	if raw, err := readTopoTechDump(exportDir, "dmidecode-type17.txt"); err == nil {
		memBankNodes = parseDIMMBankLocatorNodes(raw)
	}
	memCol := make([]int, len(hw.Memory))
	memMatched := make([]bool, len(hw.Memory))
	var memRawNodes []int
	for i, m := range hw.Memory {
		if node, ok := dimmRawNode(m, memBankNodes); ok {
			memCol[i] = node
			memMatched[i] = true
			memRawNodes = append(memRawNodes, node)
		}
	}
	memColIdx := buildMemoryColumnIndex(memRawNodes)
	for i := range hw.Memory {
		if !memMatched[i] {
			continue
		}
		col := memColIdx[memCol[i]]
		if col >= numCols {
			memMatched[i] = false
			continue
		}
		memCol[i] = col
	}

	// Map each disk to the PCI function of the controller it hangs off, read
	// from the persisted storage-controllers.txt techdump
	// (platform.StorageControllerMapScript). Lets a disk be drawn as a branch
	// of its real storage controller (SATA/AHCI, SAS HBA, RAID) — which is
	// itself a NUMA-affine PCIe device under one CPU — instead of floating in
	// a synthetic catch-all node.
	ctrlByHCTL := map[string]string{}
	if raw, err := readTopoTechDump(exportDir, "storage-controllers.txt"); err == nil {
		ctrlByHCTL = parseStorageControllerMap(raw)
	}
	// NUMA node of each PCIe function, for joining a controller BDF to a CPU
	// column (the controller itself is usually classed "SATA controller" /
	// "Serial Attached SCSI controller" and so isn't in `placed`).
	numaByBDF := map[string]int{}
	classByBDF := map[string]string{}
	modelByBDF := map[string]string{}
	for _, dev := range hw.PCIeDevices {
		bdf := ""
		if dev.Slot != nil {
			bdf = normalizeTopoBDF(*dev.Slot)
		} else if dev.BDF != nil {
			bdf = normalizeTopoBDF(*dev.BDF)
		}
		if bdf == "" {
			continue
		}
		if dev.NUMANode != nil {
			numaByBDF[bdf] = *dev.NUMANode
		}
		if dev.DeviceClass != nil {
			classByBDF[bdf] = *dev.DeviceClass
		}
		if dev.Model != nil {
			modelByBDF[bdf] = *dev.Model
		}
	}

	// diskCtrlGroups[cpuCol][ctrlBDF] = disks on that controller (cpuCol == -1
	// for controllers with no resolvable NUMA/CPU — rendered under "Other").
	type ctrlGroup struct {
		bdf   string
		disks []schema.HardwareStorage
	}
	diskCtrlGroups := map[int][]*ctrlGroup{}
	var looseDisks []schema.HardwareStorage // no HCTL / no controller match at all
	ctrlSeen := map[string]*ctrlGroup{}
	for _, d := range hw.Storage {
		hctl := ""
		if d.Slot != nil {
			hctl = strings.TrimSpace(*d.Slot)
		}
		ctrl := ""
		if hctl != "" {
			ctrl = ctrlByHCTL[hctl]
		}
		if ctrl == "" {
			looseDisks = append(looseDisks, d)
			continue
		}
		col := -1
		if n, ok := numaByBDF[ctrl]; ok {
			if ci, ok := socketIdx[n]; ok && ci < numCols {
				col = ci
			}
		}
		g := ctrlSeen[ctrl]
		if g == nil {
			g = &ctrlGroup{bdf: ctrl}
			ctrlSeen[ctrl] = g
			diskCtrlGroups[col] = append(diskCtrlGroups[col], g)
		}
		g.disks = append(g.disks, d)
	}

	// ── Layout ──────────────────────────────────────────────────────────────
	// Each CPU socket is a tall vertical bar; everything attached to it
	// branches off sideways as a vertical stack of boxes. Socket 0 sits on the
	// left with its branches growing rightward, socket 1 on the right growing
	// leftward (further sockets alternate sides, one row per pair). Disks hang
	// off their storage-controller box as a further branch. An "Other" bar
	// collects devices/disks with no resolvable socket. The figure grows
	// downward, not sideways.
	const (
		topoBarW     = 118
		topoColGap   = 46
		topoBranchW  = 208
		topoSubW     = 172
		topoBlockGap = 30
		topoMinBarH  = 92
		topoMidGap   = 72
	)

	type topoBranch struct {
		info topoCardInfo
		edge string
		subs []topoCardInfo // disk groups under a storage-controller branch
	}
	type topoBlock struct {
		head     topoCardInfo
		branches []topoBranch
	}

	// storageControllerBranch builds one branch for a controller and its disks.
	storageControllerBranch := func(g *ctrlGroup) topoBranch {
		label := "Storage ctrl"
		if c := strings.TrimSpace(classByBDF[g.bdf]); c != "" {
			label = strings.TrimSpace(strings.NewReplacer("Controller", "", "controller", "").Replace(c))
			if label == "" {
				label = "Storage"
			}
			label += " ctrl"
		}
		sub := g.bdf
		if m := strings.TrimSpace(modelByBDF[g.bdf]); m != "" && !strings.HasPrefix(m, "Device ") {
			sub = m
		}
		var tally topoStatusTally
		for _, d := range g.disks {
			tally.add(classifyTopoSeverity(d.Status))
		}
		fill, stroke, text := topoSeverityColors(tally.worst())
		return topoBranch{
			info: topoCardInfo{
				label: label, sublabel: sub, count: 1,
				statusLine: fmt.Sprintf("%d disk(s)", len(g.disks)),
				fillVar:    fill, strokeVar: stroke, textVar: text,
				detailType: "storage",
			},
			edge: "var(--ok-fg)",
			subs: buildStorageGroupCards(g.disks),
		}
	}

	// deviceBranches gathers the GPU/NIC/RAID branches for a given column
	// (col == unknownCol for the "Other" bar).
	deviceBranches := func(col int) []topoBranch {
		var out []topoBranch
		for _, kind := range kindOrder {
			var group []placedDevice
			for _, p := range placed {
				if p.col == col && p.kind == kind {
					group = append(group, p)
				}
			}
			if len(group) == 0 {
				continue
			}
			var tally topoStatusTally
			model := ""
			edgeColor := "var(--ok-fg)"
			for i, p := range group {
				sev := classifyTopoSeverity(p.dev.Status)
				if kind == "gpu" && crossNUMAWarnBDF[p.bdf] && sev < 2 {
					sev = 2
				}
				if kind == "gpu" && gpuHardwareFault && sev < 3 {
					sev = 3
				}
				tally.add(sev)
				if i == 0 && p.dev.Model != nil {
					model = *p.dev.Model
				}
				if topoEdgeColorVar(p.dev) == "var(--warn-fg)" {
					edgeColor = "var(--warn-fg)"
				}
			}
			fill, stroke, text := topoSeverityColors(tally.worst())
			out = append(out, topoBranch{
				info: topoCardInfo{
					label: kindLabel[kind], sublabel: model, count: len(group),
					statusLine: tally.line(),
					fillVar:    fill, strokeVar: stroke, textVar: text,
					detailType: kind,
				},
				edge: edgeColor,
			})
		}
		return out
	}

	var blocks []topoBlock
	for col := 0; col < numCols && col < len(hw.CPUs); col++ {
		cpu := hw.CPUs[col]
		model := ""
		if cpu.Cores != nil && cpu.Threads != nil {
			model = fmt.Sprintf("%dC / %dT", *cpu.Cores, *cpu.Threads)
		} else if cpu.Model != nil {
			model = cleanCPUModel(*cpu.Model)
		}
		socket := col
		if cpu.Socket != nil {
			socket = *cpu.Socket
		}
		var tally topoStatusTally
		tally.add(classifyTopoSeverity(cpu.Status))
		fill, stroke, text := topoSeverityColors(tally.worst())
		blk := topoBlock{head: topoCardInfo{
			label: fmt.Sprintf("CPU %d", socket), sublabel: model, count: 1,
			statusLine: tally.line(),
			fillVar:    fill, strokeVar: stroke, textVar: text,
			detailType: "cpu",
		}}

		// Memory first — wired straight to the socket's memory controller.
		var memGroup []schema.HardwareMemory
		for i, m := range hw.Memory {
			if memMatched[i] && memCol[i] == col {
				memGroup = append(memGroup, m)
			}
		}
		if len(memGroup) > 0 {
			var mt topoStatusTally
			sizeGB := 0
			for _, m := range memGroup {
				mt.add(classifyTopoSeverity(m.Status))
				if m.SizeMB != nil {
					sizeGB += *m.SizeMB / 1024
				}
			}
			mfill, mstroke, mtext := topoSeverityColors(mt.worst())
			sublabel := ""
			if sizeGB > 0 {
				sublabel = fmt.Sprintf("%d GB total", sizeGB)
			}
			blk.branches = append(blk.branches, topoBranch{
				info: topoCardInfo{
					label: "Memory", sublabel: sublabel, count: len(memGroup),
					statusLine: mt.line(),
					fillVar:    mfill, strokeVar: mstroke, textVar: mtext,
					detailType: "memory",
				},
				edge: "var(--ok-fg)",
			})
		}
		blk.branches = append(blk.branches, deviceBranches(col)...)
		for _, g := range diskCtrlGroups[col] {
			blk.branches = append(blk.branches, storageControllerBranch(g))
		}
		blocks = append(blocks, blk)
	}

	// "Other" bar: unmatched PCIe devices, unmatched storage controllers, and
	// disks with no controller/HCTL at all.
	var otherBranches []topoBranch
	otherBranches = append(otherBranches, deviceBranches(unknownCol)...)
	for _, g := range diskCtrlGroups[-1] {
		otherBranches = append(otherBranches, storageControllerBranch(g))
	}
	if len(looseDisks) > 0 {
		for _, ci := range buildStorageGroupCards(looseDisks) {
			otherBranches = append(otherBranches, topoBranch{info: ci, edge: "var(--ok-fg)"})
		}
	}
	hasOther := len(otherBranches) > 0
	if hasOther {
		fill, stroke, text := topoSeverityColors(0)
		blocks = append(blocks, topoBlock{
			head: topoCardInfo{
				label: "Other", sublabel: "no socket affinity", count: 1,
				fillVar: fill, strokeVar: stroke, textVar: text,
			},
			branches: otherBranches,
		})
	}

	var boxes []topoBox
	var pcieEdges []topoEdge

	// side: 0 = left (branches grow right), 1 = right (branches grow left).
	// CPU sockets alternate; the "Other" block is always left.
	blockSide := func(i int) int {
		if hasOther && i == len(blocks)-1 {
			return 0
		}
		return i % 2
	}
	sideHasSubs := [2]bool{}
	hasRight := false
	for i, blk := range blocks {
		s := blockSide(i)
		if s == 1 {
			hasRight = true
		}
		for _, br := range blk.branches {
			if len(br.subs) > 0 {
				sideHasSubs[s] = true
			}
		}
	}

	reach := func(s int) int {
		r := topoBarW + topoColGap + topoBranchW
		if sideHasSubs[s] {
			r += topoColGap + topoSubW
		}
		return r
	}
	leftReach := reach(0)
	svgWidth := 24 + leftReach + 24
	if hasRight {
		svgWidth = 24 + leftReach + topoMidGap + reach(1) + 24
	}

	leftBarX := 24
	leftBranchX := leftBarX + topoBarW + topoColGap
	leftSubX := leftBranchX + topoBranchW + topoColGap
	rightBarX := svgWidth - 24 - topoBarW
	rightBranchX := rightBarX - topoColGap - topoBranchW
	rightSubX := rightBranchX - topoColGap - topoSubW

	geom := func(s int) (barX, barLinkX, branchX, branchLinkX, subX int) {
		if s == 0 {
			return leftBarX, leftBarX + topoBarW, leftBranchX, leftBranchX + topoBranchW, leftSubX
		}
		return rightBarX, rightBarX, rightBranchX, rightBranchX, rightSubX
	}

	// No root/board node — board identity lives in the Firmware row below.
	// Each socket bar is an independent column with its own branch stack.

	// layoutBlock places one socket bar + its branch/sub boxes and returns the
	// bar's bottom Y.
	layoutBlock := func(blk topoBlock, s, barTop int) int {
		barX, barLinkX, branchX, branchLinkX, subX := geom(s)
		by := barTop
		for _, br := range blk.branches {
			midY := by + topoBoxHeight/2
			boxes = append(boxes, topoBox{x: branchX, y: by, w: topoBranchW, h: topoBoxHeight, topoCardInfo: br.info})
			pcieEdges = append(pcieEdges, topoEdge{x1: barLinkX, y1: midY, x2: branchLinkX, y2: midY, color: br.edge})
			advance := topoBoxHeight + topoDeviceGap + topoStackLayers(br.info.count)*topoStackStep
			if len(br.subs) > 0 {
				sy := by
				for _, sc := range br.subs {
					smid := sy + topoBoxHeight/2
					sLink := subX
					if s == 1 {
						sLink = subX + topoSubW
					}
					boxes = append(boxes, topoBox{x: subX, y: sy, w: topoSubW, h: topoBoxHeight, topoCardInfo: sc})
					pcieEdges = append(pcieEdges, topoEdge{x1: branchLinkX, y1: midY, x2: sLink, y2: smid, color: "var(--ok-fg)"})
					sy += topoBoxHeight + topoDeviceGap + topoStackLayers(sc.count)*topoStackStep
				}
				if sy-by > advance {
					advance = sy - by
				}
			}
			by += advance
		}
		barBottom := by - topoDeviceGap
		if barBottom < barTop+topoMinBarH {
			barBottom = barTop + topoMinBarH
		}
		boxes = append(boxes, topoBox{x: barX, y: barTop, w: topoBarW, h: barBottom - barTop, topoCardInfo: blk.head})
		return barBottom
	}

	rowTop := topoTopMargin
	i := 0
	for i < len(blocks) {
		s := blockSide(i)
		rowBottom := layoutBlock(blocks[i], s, rowTop)
		next := i + 1
		if next < len(blocks) && blockSide(next) == 1 && s == 0 {
			rb := layoutBlock(blocks[next], 1, rowTop)
			if rb > rowBottom {
				rowBottom = rb
			}
			next++
		}
		rowTop = rowBottom + topoBlockGap
		i = next
	}

	svgHeight := topoTopMargin + topoMinBarH
	for _, box := range boxes {
		bottom := box.y + box.h + topoStackLayers(box.count)*topoStackStep
		if bottom > svgHeight {
			svgHeight = bottom
		}
	}
	svgHeight += 24

	var b strings.Builder
	// Wrapped in its own horizontally-scrolling container (matching the
	// overflow-x:auto convention used for wide tables elsewhere in webui)
	// rather than max-width:100% — squashing a node/edge diagram to fit a
	// narrow viewport makes labels and badges illegible, whereas scrolling
	// keeps the diagram readable at its natural size on any screen width.
	b.WriteString(`<div style="overflow-x:auto">`)
	fmt.Fprintf(&b, `<svg width="%d" height="%d" viewBox="0 0 %d %d">`+"\n", svgWidth, svgHeight, svgWidth, svgHeight)
	for _, e := range pcieEdges {
		fmt.Fprintf(&b, `<line x1="%d" y1="%d" x2="%d" y2="%d" style="stroke:%s;stroke-width:2"/>`+"\n", e.x1, e.y1, e.x2, e.y2, e.color)
	}
	for _, box := range boxes {
		writeTopoBoxSVG(&b, box)
	}
	b.WriteString(`</svg></div>`)

	// Firmware (BMC/BIOS/...) and PSUs have no PCIe/CPU affinity to anchor
	// them to a column, and there can be an arbitrary number of any of them
	// — so unlike the diagram above, they're plain flex-wrap HTML below the
	// SVG rather than absolutely-positioned SVG boxes. A fixed-size SVG
	// canvas has no way to wrap overflow onto a new row, which is exactly
	// what caused these to pile up and overlap once a board had more
	// PSUs/firmware records than fit in one fixed-width row.
	//
	// Memory DIMMs that were matched to a CPU column above already got a
	// box in the SVG diagram; only DIMMs that couldn't be attached to a
	// column (see memMatched above) fall back to this row.
	var unmatchedMem []schema.HardwareMemory
	for i, m := range hw.Memory {
		if !memMatched[i] {
			unmatchedMem = append(unmatchedMem, m)
		}
	}
	if len(unmatchedMem) > 0 {
		var tally topoStatusTally
		for _, m := range unmatchedMem {
			tally.add(classifyTopoSeverity(m.Status))
		}
		fill, stroke, text := topoSeverityColors(tally.worst())
		sizeGB := 0
		for _, m := range unmatchedMem {
			if m.SizeMB != nil {
				sizeGB += *m.SizeMB / 1024
			}
		}
		sublabel := ""
		if sizeGB > 0 {
			sublabel = fmt.Sprintf("%d GB total", sizeGB)
		}
		b.WriteString(renderTopoFlexRow("Memory", []topoCardInfo{{
			label: "Memory", sublabel: sublabel, count: len(unmatchedMem),
			statusLine: tally.line(),
			fillVar:    fill, strokeVar: stroke, textVar: text,
			detailType: "memory",
		}}))
	}

	var firmwareItems []topoCardInfo
	for _, rec := range hw.Firmware {
		// Firmware records carry no per-item status in the schema (they are
		// identity, not health, facts), so each stays a neutral, uncolored
		// card rather than forcing a fake "Unknown" status line.
		fillVar, strokeVar, textVar := topoSeverityColors(0)
		firmwareItems = append(firmwareItems, topoCardInfo{
			label: rec.DeviceName, sublabel: "fw " + rec.Version, count: 1,
			fillVar: fillVar, strokeVar: strokeVar, textVar: textVar,
		})
	}
	b.WriteString(renderTopoFlexRow("Firmware", firmwareItems))

	hasPSU := len(hw.PowerSupplies) > 0
	if hasPSU {
		b.WriteString(renderTopoPSURow(hw.PowerSupplies, platform.ObservedPSUMaxW()))
	}

	// Cooling fans — one small clickable square per fan. Square SIZE encodes
	// the fan's ceiling RPM (its class); the coloured FILL rising from the
	// bottom encodes live duty cycle (current / ceiling).
	fans := dedupeFansByName(hw.Sensors)
	if len(fans) > 0 {
		current := map[string]float64{}
		for _, f := range fans {
			if f.RPM != nil {
				current[strings.TrimSpace(f.Name)] = float64(*f.RPM)
			}
		}
		b.WriteString(renderTopoFanRow(fans, platform.ResolveFanMaxRPM(current), platform.ObservedFanMaxRPM()))
	}

	if hasPSU || len(fans) > 0 {
		b.WriteString(topoLiveScript())
	}

	return topoCard("Topology", b.String())
}

// renderTopoPSURow renders the POWER SUPPLIES row: one card per PSU, coloured
// by that PSU's own status (a failed unit goes red on its own). The card shows
// input voltage and draw, and a load fill rising from the bottom — same idea
// as the fan duty-cycle fill. The load scale is the nameplate rating when the
// BMC reports it; otherwise it is the observed peak draw (observedMaxW, keyed
// by ordinal — the "autotune" recorded during any full-load run), and the
// figure is marked as an estimate.
func renderTopoPSURow(psus []schema.HardwarePowerSupply, observedMaxW map[string]float64) string {
	var b strings.Builder
	b.WriteString(topoRowHeading("Power Supplies"))
	b.WriteString(`<div style="display:flex;flex-wrap:wrap;gap:8px">`)
	for i, p := range psus {
		sev := classifyTopoSeverity(p.Status)
		_, stroke, text := topoSeverityColors(sev)

		label := fmt.Sprintf("PSU %d", i)
		if p.Slot != nil && strings.TrimSpace(*p.Slot) != "" {
			label = strings.TrimSpace(*p.Slot)
		}

		draw, haveDraw := psuDrawW(p)
		rating := 0
		if p.WattageW != nil && *p.WattageW > 0 {
			rating = *p.WattageW
		}
		// Load scale: true rating if known, else the observed peak draw — but
		// only once that peak sits meaningfully above the current draw. Until
		// a real full-load run has bumped it, the "peak" is just idle draw and
		// a load % off it would be nonsense, so fall back to plain watts.
		scaleMax := float64(rating)
		scaleEstimate := false
		if scaleMax <= 0 {
			if m := observedMaxW[strconv.Itoa(i)]; m > 0 && (!haveDraw || m >= draw*1.25) {
				scaleMax = m
				scaleEstimate = true
			}
		}

		var parts []string
		if p.InputVoltage != nil && *p.InputVoltage > 0 {
			parts = append(parts, fmt.Sprintf("%.0f V", *p.InputVoltage))
		}
		switch {
		case haveDraw && scaleMax > 0 && scaleEstimate:
			parts = append(parts, fmt.Sprintf("%.0f / ~%.0f W · ~%.0f%% load", draw, scaleMax, draw/scaleMax*100))
		case haveDraw && scaleMax > 0:
			parts = append(parts, fmt.Sprintf("%.0f / %d W · %.0f%% load", draw, rating, draw/scaleMax*100))
		case haveDraw:
			parts = append(parts, fmt.Sprintf("%.0f W", draw))
		case rating > 0:
			parts = append(parts, fmt.Sprintf("%d W rated", rating))
		}
		detail := strings.Join(parts, " · ")

		statusWord := ""
		if sev >= 2 {
			statusWord = topoSeverityStatus(p.Status)
		}

		fillH := 0.0
		if haveDraw && scaleMax > 0 {
			fillH = draw / scaleMax * 100
			if fillH < 0 {
				fillH = 0
			}
			if fillH > 100 {
				fillH = 100
			}
		}

		voltAttr := ""
		if p.InputVoltage != nil && *p.InputVoltage > 0 {
			voltAttr = fmt.Sprintf("%.0f", *p.InputVoltage)
		}
		maxSrc := "rated"
		if scaleEstimate {
			maxSrc = "observed"
		}

		fmt.Fprintf(&b, `<div class="topo-psu-tile" data-psu="%d" data-psu-max="%.0f" data-psu-max-src="%s" data-psu-v="%s" onclick="openComponentDetail('psu')" `+
			`style="position:relative;overflow:hidden;cursor:pointer;min-width:104px;padding:8px 11px;border-radius:6px;background:var(--surface-2);border:1px solid %s;color:%s">`,
			i, scaleMax, maxSrc, voltAttr, stroke, text)
		fmt.Fprintf(&b, `<div class="topo-psu-fill" style="position:absolute;left:0;right:0;bottom:0;height:%.0f%%;background:%s;opacity:.5;transition:height .8s linear"></div>`, fillH, stroke)
		fmt.Fprintf(&b, `<div style="position:relative"><div style="font-size:13px;font-weight:700">%s</div>`, html.EscapeString(label))
		fmt.Fprintf(&b, `<div class="topo-psu-detail" style="font-size:11px;opacity:.9;margin-top:2px">%s</div>`, html.EscapeString(detail))
		if statusWord != "" {
			fmt.Fprintf(&b, `<div style="font-size:10px;font-weight:700;margin-top:3px">%s</div>`, html.EscapeString(strings.ToUpper(statusWord)))
		}
		b.WriteString(`</div></div>`)
	}
	b.WriteString(`</div>`)
	return b.String()
}

// psuDrawW returns the PSU's current power draw (measured output preferred,
// else measured input).
func psuDrawW(p schema.HardwarePowerSupply) (float64, bool) {
	switch {
	case p.OutputPowerW != nil && *p.OutputPowerW > 0:
		return *p.OutputPowerW, true
	case p.InputPowerW != nil && *p.InputPowerW > 0:
		return *p.InputPowerW, true
	default:
		return 0, false
	}
}

// renderTopoFanRow renders the COOLING row. ceilByName (from
// platform.ResolveFanMaxRPM) has a value for every fan and drives tile size.
// observedByName (from platform.ObservedFanMaxRPM) holds only ceilings that
// were actually measured under load — a fan present there gets a duty-cycle
// fill; one that isn't shows no fill (ceiling not measured yet).
func renderTopoFanRow(fans []schema.HardwareFanSensor, ceilByName, observedByName map[string]float64) string {
	const (
		fanTileMin = 34 // px, the smallest-ceiling fan
		fanTileMax = 60 // px, the largest-ceiling fan
	)

	ceilMax := 0.0
	for _, v := range ceilByName {
		if v > ceilMax {
			ceilMax = v
		}
	}

	var b strings.Builder
	b.WriteString(topoRowHeading("Cooling"))
	b.WriteString(topoFanSpinStyle())
	b.WriteString(`<div style="display:flex;flex-wrap:wrap;gap:6px;align-items:flex-end">`)
	for _, f := range fans {
		name := strings.TrimSpace(f.Name)
		_, stroke, text := topoSeverityColors(classifyTopoSeverity(f.Status))
		ceil := ceilByName[name]

		sizeRatio := 1.0
		if ceilMax > 0 && ceil > 0 {
			sizeRatio = ceil / ceilMax
		}
		side := fanTileMin + int(float64(fanTileMax-fanTileMin)*sizeRatio+0.5)
		glyphSz := side * 7 / 16

		// Duty cycle: only when the ceiling was actually measured under load.
		duty := -1.0
		if _, measured := observedByName[name]; measured && ceil > 0 && f.RPM != nil {
			duty = float64(*f.RPM) / ceil * 100
			if duty < 0 {
				duty = 0
			}
			if duty > 100 {
				duty = 100
			}
		}

		title := name
		switch {
		case f.RPM == nil:
			title = name + " · no reading"
		case duty >= 0:
			title = fmt.Sprintf("%s · %d RPM · %.0f%% duty (ceiling %d)", name, *f.RPM, duty, int(ceil))
		default:
			title = fmt.Sprintf("%s · %d RPM · ceiling not measured — run Fan Ceiling Check", name, *f.RPM)
		}

		glyph := fmt.Sprintf(`<svg width="%d" height="%d" viewBox="0 0 24 24" fill="currentColor" style="opacity:.35" aria-hidden="true">`, glyphSz, glyphSz) + topoFanGlyphPaths() + `</svg>`
		if f.RPM != nil && *f.RPM > 0 {
			period := fanSpinPeriodSec(float64(*f.RPM))
			glyph = fmt.Sprintf(`<svg class="topo-fan-spin" style="animation-duration:%.2fs" width="%d" height="%d" viewBox="0 0 24 24" fill="currentColor" aria-hidden="true">`,
				period, glyphSz, glyphSz) + topoFanGlyphPaths() + `</svg>`
		}

		measured := 0
		fillH := 0.0
		if duty >= 0 {
			measured = 1
			fillH = duty
		}
		fillBar := fmt.Sprintf(`<div class="topo-fan-fill" style="position:absolute;left:0;right:0;bottom:0;height:%.0f%%;background:%s;opacity:.55;transition:height .8s linear"></div>`, fillH, stroke)

		fmt.Fprintf(&b, `<div class="topo-fan-tile" data-fan="%s" data-ceil="%d" data-measured="%d" title="%s" onclick="openComponentDetail('fan')" `+
			`style="position:relative;overflow:hidden;width:%dpx;height:%dpx;display:flex;align-items:center;justify-content:center;`+
			`border-radius:5px;background:var(--surface-2);border:1px solid %s;color:%s;cursor:pointer">`+
			`%s<span style="position:relative;display:flex">%s</span></div>`,
			html.EscapeString(name), int(ceil), measured, html.EscapeString(title),
			side, side, stroke, text, fillBar, glyph)
	}
	b.WriteString(`</div>`)
	return b.String()
}

// topoLiveScript polls the already-collected live-metrics snapshot
// (/api/metrics/latest — served from memory, no BMC call) every 5s and
// refreshes the fan tiles (spin rate, duty fill, tooltip) and PSU tiles
// (wattage) in place. 5s is the metrics collector's own sampling period, so
// polling faster only re-reads identical numbers; the endpoint is a mutex
// read + small JSON, so this stays cheap with many viewers.
func topoLiveScript() string {
	return `<script>(function(){
  var fans=document.querySelectorAll('.topo-fan-tile');
  var psus=document.querySelectorAll('.topo-psu-tile');
  if(!fans.length&&!psus.length)return;
  function period(rpm){var lo=1000,hi=13000,slow=2.2,fast=0.35;
    if(rpm<=lo)return slow;if(rpm>=hi)return fast;
    return slow+(rpm-lo)/(hi-lo)*(fast-slow);}
  function tick(){
    fetch('/api/metrics/latest',{cache:'no-store'}).then(function(r){return r.json();}).then(function(m){
      if(!m)return;
      if(m.fans){
        var by={};m.fans.forEach(function(f){by[f.name]=f.rpm;});
        fans.forEach(function(t){
          var rpm=by[t.dataset.fan];if(rpm==null)return;
          var ceil=parseFloat(t.dataset.ceil)||0;
          var svg=t.querySelector('.topo-fan-spin');
          if(svg&&rpm>0)svg.style.animationDuration=period(rpm).toFixed(2)+'s';
          var meas=t.dataset.measured==='1'&&ceil>0;
          var duty=meas?Math.max(0,Math.min(100,rpm/ceil*100)):-1;
          if(meas){var fill=t.querySelector('.topo-fan-fill');if(fill)fill.style.height=duty.toFixed(0)+'%';}
          t.title=t.dataset.fan+' · '+Math.round(rpm)+' RPM'+(meas?' · '+Math.round(duty)+'% duty (ceiling '+ceil+')':' · ceiling not measured — run Fan Ceiling Check');
        });
      }
      if(m.psus){
        psus.forEach(function(t){
          var p=m.psus[parseInt(t.dataset.psu,10)];if(!p)return;
          var w=p.power_w||0,max=parseFloat(t.dataset.psuMax)||0,v=t.dataset.psuV;
          var est=t.dataset.psuMaxSrc==='observed';
          var parts=[];
          if(v)parts.push(v+' V');
          if(w>0&&max>0){
            var pct=Math.round(w/max*100);
            parts.push(est?Math.round(w)+' / ~'+Math.round(max)+' W · ~'+pct+'% load'
                          :Math.round(w)+' / '+Math.round(max)+' W · '+pct+'% load');
          }else if(w>0)parts.push(Math.round(w)+' W');
          else if(max>0)parts.push(Math.round(max)+' W rated');
          var d=t.querySelector('.topo-psu-detail');if(d&&parts.length)d.textContent=parts.join(' · ');
          if(w>0&&max>0){var f=t.querySelector('.topo-psu-fill');if(f)f.style.height=Math.max(0,Math.min(100,w/max*100)).toFixed(0)+'%';}
        });
      }
    }).catch(function(){});
  }
  setInterval(tick,5000);tick();
})();</script>`
}

// fanSpinPeriodSec maps an absolute fan RPM to a CSS animation period (one
// full turn of the glyph, in seconds). The real period would be 60/RPM — a
// blur at any real fan speed — so it is compressed into a band the eye can
// actually read: at/below fanSpinRPMLo the glyph turns at its slowest still
// clearly-moving rate, at/above fanSpinRPMHi at the fastest rate past which
// faster is indistinguishable (and starts to stutter), linear in between.
func fanSpinPeriodSec(rpm float64) float64 {
	const (
		fanSpinRPMLo   = 1000.0
		fanSpinRPMHi   = 13000.0
		fanSpinSlowSec = 2.2
		fanSpinFastSec = 0.35
	)
	switch {
	case rpm <= fanSpinRPMLo:
		return fanSpinSlowSec
	case rpm >= fanSpinRPMHi:
		return fanSpinFastSec
	default:
		t := (rpm - fanSpinRPMLo) / (fanSpinRPMHi - fanSpinRPMLo)
		return fanSpinSlowSec + t*(fanSpinFastSec-fanSpinSlowSec)
	}
}

// topoFanSpinStyle emits the keyframes + base class for the spinning fan
// glyph once per row. A repeated identical <style> is harmless.
func topoFanSpinStyle() string {
	return `<style>@keyframes topoFanSpin{to{transform:rotate(360deg)}}` +
		`.topo-fan-spin{transform-box:fill-box;transform-origin:center;` +
		`animation-name:topoFanSpin;animation-timing-function:linear;animation-iteration-count:infinite}` +
		`@media (prefers-reduced-motion:reduce){.topo-fan-spin{animation:none}}</style>`
}

// topoFanGlyphPaths is the fan-blade drawing shared by every fan square,
// designed on a 24×24 viewBox.
func topoFanGlyphPaths() string {
	return `<ellipse cx="12" cy="6.5" rx="3.1" ry="5.2"/>` +
		`<ellipse cx="12" cy="6.5" rx="3.1" ry="5.2" transform="rotate(120 12 12)"/>` +
		`<ellipse cx="12" cy="6.5" rx="3.1" ry="5.2" transform="rotate(240 12 12)"/>` +
		`<circle cx="12" cy="12" r="2.3"/>`
}

// dedupeFansByName returns the fan sensors from a snapshot with duplicate
// names collapsed to their first occurrence, matching the ingest contract's
// "(sensor_type, name) — first wins" rule and skipping unnamed sensors.
func dedupeFansByName(sensors *schema.HardwareSensors) []schema.HardwareFanSensor {
	if sensors == nil {
		return nil
	}
	seen := map[string]bool{}
	var out []schema.HardwareFanSensor
	for _, f := range sensors.Fans {
		name := strings.TrimSpace(f.Name)
		if name == "" || seen[name] {
			continue
		}
		seen[name] = true
		out = append(out, f)
	}
	return out
}

// topoRowHeading renders the small uppercase section label shared by the
// flex rows below the SVG diagram (Firmware / Power Supplies / Cooling / ...).
func topoRowHeading(title string) string {
	return fmt.Sprintf(`<div style="font-size:11px;color:var(--muted);text-transform:uppercase;letter-spacing:.05em;margin:16px 0 6px">%s</div>`,
		html.EscapeString(title))
}

// renderTopoFlexRow renders a labeled, wrapping row of component cards.
// Returns "" if items is empty (e.g. no PSU data in this audit).
func renderTopoFlexRow(title string, items []topoCardInfo) string {
	if len(items) == 0 {
		return ""
	}
	var b strings.Builder
	b.WriteString(topoRowHeading(title))
	b.WriteString(`<div style="display:flex;flex-wrap:wrap;gap:10px">`)
	for _, item := range items {
		onclick := ""
		cursor := "default"
		if item.detailType != "" {
			onclick = fmt.Sprintf(` onclick="openComponentDetail('%s')"`, item.detailType)
			cursor = "pointer"
		}
		stackLayers := topoStackLayers(item.count)
		// Extra right/bottom padding on the wrapper reserves room for the
		// backing layers of the stack effect so they aren't clipped by the
		// flex container.
		fmt.Fprintf(&b, `<div style="position:relative;padding-right:%dpx;padding-bottom:%dpx">`,
			stackLayers*topoStackStep, stackLayers*topoStackStep)
		for i := stackLayers; i >= 1; i-- {
			off := i * topoStackStep
			fmt.Fprintf(&b, `<div style="position:absolute;top:%dpx;left:%dpx;right:0;bottom:0;border-radius:6px;background:%s;border:1px solid %s;opacity:.55"></div>`,
				off, off, item.fillVar, item.strokeVar)
		}
		fmt.Fprintf(&b, `<div%s style="position:relative;cursor:%s;min-width:160px;padding:10px 12px;border-radius:6px;background:%s;border:1px solid %s;color:%s">`,
			onclick, cursor, item.fillVar, item.strokeVar, item.textVar)
		label := item.label
		if item.count > 1 {
			label = fmt.Sprintf("%s ×%d", item.label, item.count)
		}
		fmt.Fprintf(&b, `<div style="font-size:13px;font-weight:700">%s</div>`, html.EscapeString(label))
		if item.sublabel != "" {
			fmt.Fprintf(&b, `<div style="font-size:11px;opacity:.85">%s</div>`, html.EscapeString(item.sublabel))
		}
		if item.statusLine != "" {
			fmt.Fprintf(&b, `<div style="font-size:11px;font-weight:600;margin-top:4px">%s</div>`, html.EscapeString(item.statusLine))
		}
		b.WriteString(`</div></div>`)
	}
	b.WriteString(`</div>`)
	return b.String()
}

// buildStorageGroupCards groups disks by media type ("SSD"/"HDD"/"NVMe", or
// "Disk" when Type is absent) into one card per type: label "SSD ×2", a
// "<model> · <capacity> total" sublabel, and the worst-of status line for
// that group. Order follows first appearance in hw.Storage. Every card is
// clickable through to the shared "storage" component-detail modal.
func buildStorageGroupCards(disks []schema.HardwareStorage) []topoCardInfo {
	if len(disks) == 0 {
		return nil
	}
	type diskGroup struct {
		label  string
		tally  topoStatusTally
		count  int
		sizeGB int
	}
	var order []string
	groups := map[string]*diskGroup{}
	for _, d := range disks {
		label := "Disk"
		if d.Type != nil && strings.TrimSpace(*d.Type) != "" {
			label = strings.TrimSpace(*d.Type)
		}
		g := groups[label]
		if g == nil {
			g = &diskGroup{label: label}
			groups[label] = g
			order = append(order, label)
		}
		g.count++
		g.tally.add(classifyTopoSeverity(d.Status))
		if d.SizeGB != nil {
			g.sizeGB += *d.SizeGB
		}
	}
	var cards []topoCardInfo
	for _, label := range order {
		g := groups[label]
		fill, stroke, text := topoSeverityColors(g.tally.worst())
		// Capacity only — the model string is too long for an SVG node label
		// and is one click away in the storage detail modal anyway.
		sublabel := ""
		if g.sizeGB > 0 {
			if g.sizeGB >= 1024 {
				sublabel = fmt.Sprintf("%.1f TB total", float64(g.sizeGB)/1024)
			} else {
				sublabel = fmt.Sprintf("%d GB total", g.sizeGB)
			}
		}
		cards = append(cards, topoCardInfo{
			label: g.label, sublabel: sublabel, count: g.count,
			statusLine: g.tally.line(),
			fillVar:    fill, strokeVar: stroke, textVar: text,
			detailType: "storage",
		})
	}
	return cards
}

// parseStorageControllerMap parses storage-controllers.txt
// (platform.StorageControllerMapScript output: one
// "<name> hctl=<h:c:t:l> ctrl=<dddd:bb:dd.f>" line per disk) into a map from
// SCSI HCTL address (which matches schema.HardwareStorage.Slot) to the
// normalized PCI BDF of the controller the disk hangs off. Disks with an
// empty hctl (NVMe) are skipped — they have no HCTL Slot to join on.
func parseStorageControllerMap(raw string) map[string]string {
	out := map[string]string{}
	for _, line := range strings.Split(raw, "\n") {
		var hctl, ctrl string
		for _, f := range strings.Fields(line) {
			if v, ok := strings.CutPrefix(f, "hctl="); ok {
				hctl = v
			}
			if v, ok := strings.CutPrefix(f, "ctrl="); ok {
				ctrl = normalizeTopoBDF(v)
			}
		}
		if hctl != "" && ctrl != "" {
			out[hctl] = ctrl
		}
	}
	return out
}

// cleanCPUModel trims the marketing noise ("(R)", "(TM)", "CPU", "Processor")
// out of a dmidecode CPU model string so it fits the narrow socket bar.
func cleanCPUModel(s string) string {
	s = strings.NewReplacer(
		"(R)", "", "(r)", "", "(TM)", "", "(tm)", "",
		" CPU", "", " Processor", "", " processor", "",
	).Replace(s)
	return strings.Join(strings.Fields(s), " ")
}

func writeTopoBoxSVG(b *strings.Builder, box topoBox) {
	onclick := ""
	cursor := "default"
	if box.detailType != "" {
		onclick = fmt.Sprintf(` onclick="openComponentDetail('%s')"`, box.detailType)
		cursor = "pointer"
	}
	fmt.Fprintf(b, `<g%s style="cursor:%s">`, onclick, cursor)

	// Stack-of-cards effect: faint offset rects behind the front card when
	// this box represents more than one physical component (e.g. 4 GPUs in
	// one NUMA column), so a group reads as "a deck of N" rather than a
	// single item. Peeks toward the bottom-right, into space already
	// reserved between this box and the next one in the column.
	for i := topoStackLayers(box.count); i >= 1; i-- {
		off := i * topoStackStep
		fmt.Fprintf(b, `<rect x="%d" y="%d" width="%d" height="%d" rx="6" ry="6" style="fill:%s;stroke:%s;opacity:.55"/>`+"\n",
			box.x+off, box.y+off, box.w, box.h, box.fillVar, box.strokeVar)
	}

	fmt.Fprintf(b, `<rect x="%d" y="%d" width="%d" height="%d" rx="6" ry="6" style="fill:%s;stroke:%s"/>`+"\n",
		box.x, box.y, box.w, box.h, box.fillVar, box.strokeVar)

	label := box.label
	if box.count > 1 {
		label = fmt.Sprintf("%s ×%d", box.label, box.count)
	}
	fmt.Fprintf(b, `<text x="%d" y="%d" style="fill:%s;font-size:13px;font-weight:700">%s</text>`+"\n",
		box.x+10, box.y+20, box.textVar, html.EscapeString(label))
	if box.sublabel != "" {
		fmt.Fprintf(b, `<text x="%d" y="%d" style="fill:%s;font-size:11px;opacity:.85">%s</text>`+"\n",
			box.x+10, box.y+36, box.textVar, html.EscapeString(truncateTopoLabel(box.sublabel, 26)))
	}
	if box.statusLine != "" {
		fmt.Fprintf(b, `<text x="%d" y="%d" style="fill:%s;font-size:10px;font-weight:600">%s</text>`+"\n",
			box.x+10, box.y+box.h-10, box.textVar, html.EscapeString(box.statusLine))
	}
	b.WriteString(`</g>` + "\n")
}

func truncateTopoLabel(s string, max int) string {
	if len(s) <= max {
		return s
	}
	if max <= 1 {
		return s[:max]
	}
	return s[:max-1] + "…"
}

// ---------------------------------------------------------------------------
// Separate NVLink topology card (read from techdump, not written to any
// ingest contract)
// ---------------------------------------------------------------------------

type topoNVLinkPort struct {
	Index          int
	Active         bool
	SpeedGBs       *float64
	ReplayErrors   int64
	RecoveryErrors int64
	CRCErrors      int64
}

var (
	topoNVLinkGPUHeaderRe = regexp.MustCompile(`^GPU (\d+):`)
	topoNVLinkSpeedLineRe = regexp.MustCompile(`^Link (\d+):\s*([\d.]+)\s*GB/s`)
	topoNVLinkInactiveRe  = regexp.MustCompile(`^Link (\d+):\s*<inactive>`)
)

func readTopoNVLinkStatus(exportDir string) (map[int][]topoNVLinkPort, error) {
	raw, err := readTopoTechDump(exportDir, "nvidia-smi-nvlink-status.txt")
	if err != nil {
		return nil, err
	}
	return parseTopoNVLinkStatus(raw), nil
}

func parseTopoNVLinkStatus(raw string) map[int][]topoNVLinkPort {
	result := map[int][]topoNVLinkPort{}
	currentGPU := -1
	for _, line := range strings.Split(raw, "\n") {
		trimmed := strings.TrimSpace(line)
		if m := topoNVLinkGPUHeaderRe.FindStringSubmatch(trimmed); m != nil {
			currentGPU, _ = strconv.Atoi(m[1])
			continue
		}
		if currentGPU < 0 {
			continue
		}
		if m := topoNVLinkInactiveRe.FindStringSubmatch(trimmed); m != nil {
			idx, _ := strconv.Atoi(m[1])
			result[currentGPU] = append(result[currentGPU], topoNVLinkPort{Index: idx, Active: false})
			continue
		}
		if m := topoNVLinkSpeedLineRe.FindStringSubmatch(trimmed); m != nil {
			idx, _ := strconv.Atoi(m[1])
			port := topoNVLinkPort{Index: idx, Active: true}
			if speed, err := strconv.ParseFloat(m[2], 64); err == nil {
				port.SpeedGBs = &speed
			}
			result[currentGPU] = append(result[currentGPU], port)
		}
	}
	return result
}

func readTopoNVLinkErrors(exportDir string) (map[int]map[int][3]int64, error) {
	raw, err := readTopoTechDump(exportDir, "nvidia-smi-nvlink-errors.txt")
	if err != nil {
		return nil, err
	}
	return parseTopoNVLinkErrors(raw), nil
}

// parseTopoNVLinkErrors returns, per GPU then link index, [replay, recovery, crc].
func parseTopoNVLinkErrors(raw string) map[int]map[int][3]int64 {
	return platform.ParseNvidiaNVLinkErrors(raw)
}

// renderTopoNVLinkCard renders the separate NVLink topology card. Returns ""
// if there are fewer than 2 NVIDIA GPUs, or the nvidia-smi nvlink techdump
// wasn't captured (older audit, or nvidia-smi unavailable on that run).
func renderTopoNVLinkCard(hw schema.HardwareSnapshot, exportDir string) string {
	gpuCount := 0
	for _, dev := range hw.PCIeDevices {
		if dev.DeviceClass != nil && isGPUDeviceClass(*dev.DeviceClass) {
			gpuCount++
		}
	}
	if gpuCount < 2 {
		return ""
	}

	status, err := readTopoNVLinkStatus(exportDir)
	if err != nil || len(status) == 0 {
		return topoCard("NVLink Topology", `<span class="badge badge-unknown">nvidia-smi nvlink data unavailable</span>`)
	}
	errors, _ := readTopoNVLinkErrors(exportDir)

	topoMatrix, _ := readGPUTopologyMatrix(exportDir)
	pairs := parseGPUPairAdjacency(topoMatrix)

	var bodyB strings.Builder
	if gpuCount <= 4 && len(pairs) > 0 {
		// Small GPU count: per-pair box+line with per-link detail.
		for _, pair := range pairs {
			activeCount, total, hasError := 0, 0, false
			for _, port := range status[pair.GPUA] {
				total++
				if port.Active {
					activeCount++
				}
			}
			for _, counters := range errors[pair.GPUA] {
				if counters[0] != 0 || counters[1] != 0 || counters[2] != 0 {
					hasError = true
				}
			}
			color := "var(--ok-fg)"
			switch {
			case hasError:
				color = "var(--crit-fg)"
			case total > 0 && activeCount < total:
				color = "var(--warn-fg)"
			}
			fmt.Fprintf(&bodyB, `<div style="display:flex;align-items:center;gap:12px;margin-bottom:10px">`+
				`<div style="padding:8px 12px;border:1px solid var(--border);border-radius:6px">GPU %d</div>`+
				`<div style="flex:1;height:2px;background:%s"></div>`+
				`<div style="padding:8px 12px;border:1px solid var(--border);border-radius:6px">GPU %d</div>`+
				`<div style="font-size:12px;color:var(--muted)">%d/%d links active%s</div>`+
				`</div>`,
				pair.GPUA, color, pair.GPUB, activeCount, total, errNoteSuffix(hasError))
		}
	} else if len(pairs) > 0 {
		// Larger GPU counts (NVSwitch fabric): aggregate pair table instead of
		// an unreadable all-to-all graph.
		bodyB.WriteString(`<table><thead><tr><th>GPU A</th><th>GPU B</th><th>NVLinks</th></tr></thead><tbody>`)
		for _, pair := range pairs {
			fmt.Fprintf(&bodyB, `<tr><td>GPU %d</td><td>GPU %d</td><td>%d</td></tr>`, pair.GPUA, pair.GPUB, pair.NVLinks)
		}
		bodyB.WriteString(`</tbody></table>`)
	} else {
		bodyB.WriteString(`<span class="badge badge-unknown">No NVLink-bonded GPU pairs found</span>`)
	}

	return topoCard("NVLink Topology", bodyB.String())
}

func errNoteSuffix(hasError bool) string {
	if hasError {
		return " — errors detected"
	}
	return ""
}

// ---------------------------------------------------------------------------
// Inventory fallback for the component-detail modal
//
// handleAPIComponentDetail normally sources records from app.ComponentStatusDB,
// which only gains entries once something has actually written a status
// observation (SAT run, watchdog tick, ...). On a freshly booted host that
// hasn't run SAT yet, StatusDB can be entirely empty for a component type even
// though the /topo card for it already shows "N OK" — that card reads
// schema.HardwareComponentStatus.Status straight from the audit snapshot.
// inventoryFallbackRecords bridges that gap by building synthetic records
// from the same snapshot/classifiers the topology card uses, so the two
// views never disagree about how many devices exist or their status.
// ---------------------------------------------------------------------------

// topoSeverityStatus renders classifyTopoSeverity's rank back into the status
// string vocabulary renderComponentDetail/chipLetterClass expect ("OK",
// "Warning", "Critical", "Unknown") — kept in lockstep with classifyTopoSeverity
// so a device the topo card counts as "OK" is never shown here as "Unknown".
func topoSeverityStatus(status *string) string {
	switch classifyTopoSeverity(status) {
	case 3:
		return "Critical"
	case 2:
		return "Warning"
	case 1:
		return "OK"
	default:
		return "Unknown"
	}
}

// pcieDeviceKind classifies a PCIe device the same way renderTopoMainDiagram
// does, returning "" for devices that aren't GPU/NIC/RAID.
func pcieDeviceKind(dev schema.HardwarePCIeDevice) string {
	switch {
	case dev.DeviceClass != nil && isGPUDeviceClass(*dev.DeviceClass):
		return "gpu"
	case isNICDeviceClassDev(dev):
		return "nic"
	case dev.DeviceClass != nil && isRAIDControllerClass(*dev.DeviceClass):
		return "raid"
	default:
		return ""
	}
}

// pcieDeviceKey builds a stable, human-readable component key for a PCIe
// device: "<kind>:<bdf>" when a slot/BDF is known, else "<kind>:<index>".
func pcieDeviceKey(kind string, index int, dev schema.HardwarePCIeDevice) string {
	bdf := ""
	if dev.Slot != nil {
		bdf = normalizeTopoBDF(*dev.Slot)
	} else if dev.BDF != nil {
		bdf = normalizeTopoBDF(*dev.BDF)
	}
	if bdf != "" {
		return kind + ":" + bdf
	}
	return fmt.Sprintf("%s:%d", kind, index)
}

// inventoryFallbackRecords builds ComponentStatusRecord entries straight from
// the audit inventory (bee-audit.json) for the given component type, used
// when ComponentStatusDB has no matching records yet. Records carry only
// ComponentKey/Status — no LastCheckedAt/History — so renderComponentDetail
// renders them without a "checked at" timestamp or sparkline.
func inventoryFallbackRecords(compType string, opts HandlerOptions) []app.ComponentStatusRecord {
	data, err := loadSnapshot(opts.AuditPath)
	if err != nil {
		return nil
	}
	var ingest schema.HardwareIngestRequest
	if err := json.Unmarshal(data, &ingest); err != nil {
		return nil
	}
	hw := ingest.Hardware

	var records []app.ComponentStatusRecord
	switch compType {
	case "cpu":
		for i, cpu := range hw.CPUs {
			key := fmt.Sprintf("cpu:%d", i)
			if cpu.Socket != nil {
				key = fmt.Sprintf("cpu:socket%d", *cpu.Socket)
			}
			records = append(records, app.ComponentStatusRecord{ComponentKey: key, Status: topoSeverityStatus(cpu.Status)})
		}
	case "memory":
		for i, m := range hw.Memory {
			key := fmt.Sprintf("memory:%d", i)
			if m.Slot != nil && strings.TrimSpace(*m.Slot) != "" {
				key = "memory:" + strings.TrimSpace(*m.Slot)
			}
			records = append(records, app.ComponentStatusRecord{ComponentKey: key, Status: topoSeverityStatus(m.Status)})
		}
	case "storage":
		for i, s := range hw.Storage {
			key := fmt.Sprintf("storage:%d", i)
			if s.Slot != nil && strings.TrimSpace(*s.Slot) != "" {
				key = "storage:" + strings.TrimSpace(*s.Slot)
			}
			records = append(records, app.ComponentStatusRecord{ComponentKey: key, Status: topoSeverityStatus(s.Status)})
		}
	case "psu":
		for i, p := range hw.PowerSupplies {
			key := fmt.Sprintf("psu:%d", i)
			if p.Slot != nil && strings.TrimSpace(*p.Slot) != "" {
				key = "psu:" + strings.TrimSpace(*p.Slot)
			}
			records = append(records, app.ComponentStatusRecord{ComponentKey: key, Status: topoSeverityStatus(p.Status)})
		}
	case "fan":
		for i, f := range dedupeFansByName(hw.Sensors) {
			name := strings.TrimSpace(f.Name)
			key := fmt.Sprintf("fan:%d", i)
			if name != "" {
				key = "fan:" + name
			}
			records = append(records, app.ComponentStatusRecord{ComponentKey: key, Status: topoSeverityStatus(f.Status)})
		}
	case "gpu", "nic", "raid":
		for i, dev := range hw.PCIeDevices {
			if pcieDeviceKind(dev) != compType {
				continue
			}
			key := pcieDeviceKey(compType, i, dev)
			records = append(records, app.ComponentStatusRecord{ComponentKey: key, Status: topoSeverityStatus(dev.Status)})
		}
	}
	return records
}