feat: add get_shape_library tool for AI icon discovery (#335)

* feat: add get_shape_library tool for AI icon discovery

- Add server-side tool that returns shape library documentation
- AI can fetch icon/shape names on-demand before generating diagrams
- Includes path traversal protection and input sanitization
- Library index embedded in tool description for discoverability
- Supports 33 libraries: AWS, Azure, GCP, Kubernetes, Cisco, etc.

* fix: improve get_shape_library error handling and imports

- Move fs/path imports to top of file (avoid dynamic imports per call)
- Distinguish file-not-found vs other errors in catch block
- Include invalid input in validation error message
- Log unexpected errors for debugging

* docs: add get_shape_library to system prompt tool list

- Add Tool4 (get_shape_library) to available tools section
- Add usage guidance in 'Choose the right tool' section
- Update AWS icons note to reference get_shape_library for icon discovery

* fix: display get_shape_library tool output in chat UI

* fix: correct state check for get_shape_library output display

* fix: make get_shape_library output respect fold state

* style: auto-format with Biome

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

app/api/chat/route.ts

@@ -8,7 +8,9 @@ import {
     stepCountIs,
     streamText,
 } from "ai"
+import fs from "fs/promises"
 import { jsonrepair } from "jsonrepair"
+import path from "path"
 import { z } from "zod"
 import { getAIModel, supportsPromptCaching } from "@/lib/ai-providers"
 import { findCachedResponse } from "@/lib/cached-responses"
@@ -596,6 +598,69 @@ Example: If previous output ended with '<mxCell id="x" style="rounded=1', contin
                         ),
                 }),
             },
+            get_shape_library: {
+                description: `Get draw.io shape/icon library documentation with style syntax and shape names.
+
+Available libraries:
+- Cloud: aws4, azure2, gcp2, alibaba_cloud, openstack, salesforce
+- Networking: cisco19, network, kubernetes, vvd, rack
+- Business: bpmn, lean_mapping
+- General: flowchart, basic, arrows2, infographic, sitemap
+- UI/Mockups: android
+- Enterprise: citrix, sap, mscae, atlassian
+- Engineering: fluidpower, electrical, pid, cabinets, floorplan
+- Icons: webicons
+
+Call this tool to get shape names and usage syntax for a specific library.`,
+                inputSchema: z.object({
+                    library: z
+                        .string()
+                        .describe(
+                            "Library name (e.g., 'aws4', 'kubernetes', 'flowchart')",
+                        ),
+                }),
+                execute: async ({ library }) => {
+                    // Sanitize input - prevent path traversal attacks
+                    const sanitizedLibrary = library
+                        .toLowerCase()
+                        .replace(/[^a-z0-9_-]/g, "")
+
+                    if (sanitizedLibrary !== library.toLowerCase()) {
+                        return `Invalid library name "${library}". Use only letters, numbers, underscores, and hyphens.`
+                    }
+
+                    const baseDir = path.join(
+                        process.cwd(),
+                        "docs/shape-libraries",
+                    )
+                    const filePath = path.join(
+                        baseDir,
+                        `${sanitizedLibrary}.md`,
+                    )
+
+                    // Verify path stays within expected directory
+                    const resolvedPath = path.resolve(filePath)
+                    if (!resolvedPath.startsWith(path.resolve(baseDir))) {
+                        return `Invalid library path.`
+                    }
+
+                    try {
+                        const content = await fs.readFile(filePath, "utf-8")
+                        return content
+                    } catch (error) {
+                        if (
+                            (error as NodeJS.ErrnoException).code === "ENOENT"
+                        ) {
+                            return `Library "${library}" not found. Available: aws4, azure2, gcp2, alibaba_cloud, cisco19, kubernetes, network, bpmn, flowchart, basic, arrows2, vvd, salesforce, citrix, sap, mscae, atlassian, fluidpower, electrical, pid, cabinets, floorplan, webicons, infographic, sitemap, android, lean_mapping, openstack, rack`
+                        }
+                        console.error(
+                            `[get_shape_library] Error loading "${library}":`,
+                            error,
+                        )
+                        return `Error loading library "${library}". Please try again.`
+                    }
+                },
+            },
         },
         ...(process.env.TEMPERATURE !== undefined && {
             temperature: parseFloat(process.env.TEMPERATURE),