Render mermaid diagram per risk assessment scope

Each scope card now shows a flowchart of its nodes, processes, and
threats, with a distinct shape per type: stadium for entities,
hexagon for boundaries, rectangle for assets, cylinder for data, and
a red hexagon for threats attached via dashed edges to their process
target. The Mermaid source is built on the backend and exposed as a
new `mermaid` field on RiskAssessmentScope; the frontend just renders
it via @probo/ui's MermaidDiagram and shows a copy button + legend.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/riskmanagement/mermaid.go

@@ -0,0 +1,157 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package riskmanagement
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"go.gearno.de/kit/pg"
+	"go.probo.inc/probo/pkg/coredata"
+	"go.probo.inc/probo/pkg/gid"
+)
+
+func (s *Service) BuildScopeMermaidChart(ctx context.Context, scope coredata.Scoper, scopeID gid.GID) (string, error) {
+	var (
+		nodes     coredata.RiskAssessmentNodes
+		processes coredata.RiskAssessmentProcesses
+		threats   coredata.RiskAssessmentThreats
+	)
+
+	err := s.pg.WithConn(ctx, func(ctx context.Context, conn pg.Querier) error {
+		if err := nodes.LoadAllByRiskAssessmentScopeID(ctx, conn, scope, scopeID); err != nil {
+			return fmt.Errorf("cannot load nodes: %w", err)
+		}
+		if err := processes.LoadAllByRiskAssessmentScopeID(ctx, conn, scope, scopeID); err != nil {
+			return fmt.Errorf("cannot load processes: %w", err)
+		}
+		if err := threats.LoadAllByRiskAssessmentScopeID(ctx, conn, scope, scopeID); err != nil {
+			return fmt.Errorf("cannot load threats: %w", err)
+		}
+		return nil
+	})
+	if err != nil {
+		return "", err
+	}
+
+	return buildScopeMermaidChart(nodes, processes, threats), nil
+}
+
+func buildScopeMermaidChart(
+	nodes coredata.RiskAssessmentNodes,
+	processes coredata.RiskAssessmentProcesses,
+	threats coredata.RiskAssessmentThreats,
+) string {
+	if len(nodes) == 0 {
+		return ""
+	}
+
+	nodeAlias := make(map[gid.GID]string, len(nodes))
+	for i, n := range nodes {
+		nodeAlias[n.ID] = fmt.Sprintf("n%d", i)
+	}
+
+	var b strings.Builder
+	b.WriteString("flowchart LR\n")
+
+	for _, n := range nodes {
+		id := nodeAlias[n.ID]
+		fmt.Fprintf(&b, "  %s\n", mermaidNodeShape(n.NodeType, id, n.Name))
+		fmt.Fprintf(&b, "  class %s %s\n", id, mermaidNodeClass(n.NodeType))
+	}
+
+	for _, p := range processes {
+		src, srcOK := nodeAlias[p.SourceNodeID]
+		dst, dstOK := nodeAlias[p.TargetNodeID]
+		if !srcOK || !dstOK {
+			continue
+		}
+		fmt.Fprintf(&b, "  %s -- \"%s\" --> %s\n", src, escapeMermaidLabel(p.Name), dst)
+	}
+
+	processTarget := make(map[gid.GID]gid.GID, len(processes))
+	for _, p := range processes {
+		processTarget[p.ID] = p.TargetNodeID
+	}
+
+	for i, t := range threats {
+		target, ok := processTarget[t.ProcessID]
+		if !ok {
+			continue
+		}
+		targetAlias, ok := nodeAlias[target]
+		if !ok {
+			continue
+		}
+		tid := fmt.Sprintf("t%d", i)
+		label := escapeMermaidLabel(fmt.Sprintf("%s (%s)", t.Name, t.Category))
+		fmt.Fprintf(&b, "  %s{{\"%s\"}}\n", tid, label)
+		fmt.Fprintf(&b, "  class %s nodeThreat\n", tid)
+		fmt.Fprintf(&b, "  %s -.-> %s\n", tid, targetAlias)
+	}
+
+	b.WriteString("  classDef nodeEntity fill:#dbeafe,stroke:#1d4ed8,color:#1e3a8a\n")
+	b.WriteString("  classDef nodeBoundary fill:#fef3c7,stroke:#b45309,color:#78350f\n")
+	b.WriteString("  classDef nodeAsset fill:#e5e7eb,stroke:#374151,color:#111827\n")
+	b.WriteString("  classDef nodeData fill:#dcfce7,stroke:#15803d,color:#14532d\n")
+	b.WriteString("  classDef nodeThreat fill:#fee2e2,stroke:#b91c1c,color:#7f1d1d\n")
+
+	return strings.TrimRight(b.String(), "\n")
+}
+
+func mermaidNodeShape(t coredata.RiskAssessmentNodeType, id, name string) string {
+	label := `"` + escapeMermaidLabel(name) + `"`
+	switch t {
+	case coredata.RiskAssessmentNodeTypeEntity:
+		return fmt.Sprintf("%s([%s])", id, label)
+	case coredata.RiskAssessmentNodeTypeBoundary:
+		return fmt.Sprintf("%s{{%s}}", id, label)
+	case coredata.RiskAssessmentNodeTypeData:
+		return fmt.Sprintf("%s[(%s)]", id, label)
+	case coredata.RiskAssessmentNodeTypeAsset:
+		fallthrough
+	default:
+		return fmt.Sprintf("%s[%s]", id, label)
+	}
+}
+
+func mermaidNodeClass(t coredata.RiskAssessmentNodeType) string {
+	switch t {
+	case coredata.RiskAssessmentNodeTypeEntity:
+		return "nodeEntity"
+	case coredata.RiskAssessmentNodeTypeBoundary:
+		return "nodeBoundary"
+	case coredata.RiskAssessmentNodeTypeData:
+		return "nodeData"
+	case coredata.RiskAssessmentNodeTypeAsset:
+		fallthrough
+	default:
+		return "nodeAsset"
+	}
+}
+
+var mermaidLabelReplacer = strings.NewReplacer(
+	"&", "&amp;",
+	`"`, "#quot;",
+	"<", "&lt;",
+	">", "&gt;",
+	"\r\n", " ",
+	"\n", " ",
+)
+
+func escapeMermaidLabel(s string) string {
+	return mermaidLabelReplacer.Replace(s)
+}