feat: add link understanding pipeline (#1637) (thanks @dasilva333)

CHANGELOG.md

@@ -11,6 +11,7 @@ Docs: https://docs.clawd.bot
 - Docs: expand FAQ (migration, scheduling, concurrency, model recommendations, OpenAI subscription auth, Pi sizing, hackable install, docs SSL workaround).
 - Docs: add verbose installer troubleshooting guidance.
 - Docs: update Fly.io guide notes.
+- Tools: add link understanding with CLI preprocessing, SSRF guard, and structured link summaries. (#1637) Thanks @dasilva333.
 - Docs: add Bedrock EC2 instance role setup + IAM steps. (#1625) Thanks @sergical. https://docs.clawd.bot/bedrock
 - Exec approvals: forward approval prompts to chat with `/approve` for all channels (including plugins). (#1621) Thanks @czekaj. https://docs.clawd.bot/tools/exec-approvals https://docs.clawd.bot/tools/slash-commands
 - Gateway: expose config.patch in the gateway tool with safe partial updates + restart sentinel. (#1653) Thanks @Glucksberg.

docs/docs.json

@@ -1005,6 +1005,7 @@
           "plugins/zalouser",
           "tools/exec",
           "tools/web",
+          "tools/link-understanding",
           "tools/apply-patch",
           "tools/elevated",
           "tools/browser",

docs/gateway/configuration.md

@@ -2010,6 +2010,35 @@ Example:
 }
 ```
 
+`tools.links` configures link understanding (URL preprocessing via CLI):
+- `tools.links.enabled`: enable/disable link understanding (default: enabled when models are configured).
+- `tools.links.maxLinks`: max URLs per message (default 3).
+- `tools.links.timeoutSeconds`: default CLI timeout (default 30).
+- `tools.links.scope`: optional gating rules (same shape as media understanding scope).
+- `tools.links.models`: ordered CLI entries (fallbacks in order).
+  - `command`: executable to run (required).
+  - `args`: templated args (supports `{{LinkUrl}}`).
+  - `timeoutSeconds`: optional per-entry override.
+
+Example:
+```json5
+{
+  tools: {
+    links: {
+      enabled: true,
+      maxLinks: 2,
+      scope: {
+        default: "deny",
+        rules: [{ action: "allow", match: { chatType: "direct" } }]
+      },
+      models: [
+        { command: "link-understand", args: ["--url", "{{LinkUrl}}"] }
+      ]
+    }
+  }
+}
+```
+
 `agents.defaults.subagents` configures sub-agent defaults:
 - `model`: default model for spawned sub-agents (string or `{ primary, fallbacks }`). If omitted, sub-agents inherit the caller’s model unless overridden per agent or per call.
 - `maxConcurrent`: max concurrent sub-agent runs (default 1)
@@ -3180,7 +3209,7 @@ clawdbot dns setup --apply
 
 ## Template variables
 
-Template placeholders are expanded in `tools.media.*.models[].args` and `tools.media.models[].args` (and any future templated argument fields).
+Template placeholders are expanded in `tools.media.*.models[].args`, `tools.media.models[].args`, and `tools.links.models[].args` (and any future templated argument fields).
 
 | Variable | Description |
 |----------|-------------|
@@ -3195,6 +3224,7 @@ Template placeholders are expanded in `tools.media.*.models[].args` and `tools.m
 | `{{MediaUrl}}` | Inbound media pseudo-URL (if present) |
 | `{{MediaPath}}` | Local media path (if downloaded) |
 | `{{MediaType}}` | Media type (image/audio/document/…) |
+| `{{LinkUrl}}` | URL currently being processed (link understanding only) |
 | `{{Transcript}}` | Audio transcript (when enabled) |
 | `{{Prompt}}` | Resolved media prompt for CLI entries |
 | `{{MaxChars}}` | Resolved max output chars for CLI entries |

docs/tools/index.md

@@ -232,6 +232,13 @@ Notes:
 - See [Web tools](/tools/web) for setup.
 - See [Firecrawl](/tools/firecrawl) for the optional anti-bot fallback.
 
+### Link understanding (inbound)
+Preprocess inbound messages by running a CLI on detected URLs and appending the
+results to the message body before the agent sees it. This is **not** an agent
+tool; it runs in the inbound auto-reply pipeline.
+
+See [Link understanding](/tools/link-understanding) for setup and configuration.
+
 ### `browser`
 Control the dedicated clawd browser.
 

docs/tools/link-understanding.md

@@ -0,0 +1,326 @@
+---
+summary: "Run a CLI on URLs in inbound messages and inject results before the agent replies"
+read_when:
+  - You want to summarize or enrich URLs in inbound messages
+  - You need to enable or scope link understanding
+  - You want to wire a custom CLI to preprocess links
+---
+
+# Link understanding
+
+Link understanding is the **inbound URL enrichment pipeline**: Clawdbot detects
+links in a message, runs your **local CLI** to interpret them, and injects the
+results into the message body **before the agent sees it**. The goal is a
+predictable, structured prompt envelope without adding a browsing tool.
+
+This is **not** an agent tool. It is a preprocessing step in the auto-reply
+pipeline, shared across all channels (including webchat).
+
+## What it enables
+
+- Summarize or extract data from links (docs, tickets, dashboards, runbooks).
+- Inject structured context (titles, owners, status, timestamps, key facts).
+- Normalize or transform link payloads (HTML → text, JSON → bullets).
+- Gate link processing by channel, chat type, or session key.
+- Apply SSRF protections before your CLI runs.
+
+## When it runs (pipeline order)
+
+Link understanding runs after inbound normalization and media understanding,
+but before the agent executes the reply run:
+
+1) Inbound message is normalized and routed.
+2) Media understanding may rewrite the body (images/audio/video).
+3) Link understanding detects URLs in the current command/body and appends results.
+4) The agent receives the final body and command parsing uses the updated text.
+
+## How it works
+
+1) Clawdbot scans the inbound message for **bare** `http/https` URLs.
+2) It dedupes links in order and caps them at `tools.links.maxLinks` (default 3).
+3) For each link, it runs your configured CLI entries **in order** until one returns non-empty stdout.
+4) It appends the resulting outputs to the message body (structured envelope).
+5) The agent sees the original text plus the appended link outputs.
+
+No requests are made by Clawdbot itself; **your CLI does the fetching/parsing**.
+
+## URL detection rules
+
+- Only **bare URLs** are extracted (e.g. `https://example.com`).
+- Markdown links are ignored (`[label](https://example.com)` is stripped).
+- Links are deduped (first occurrence wins).
+- Only `http` and `https` are allowed.
+- Local and private hosts are blocked (see **Security** below).
+
+## Configuration
+
+Link understanding is configured under `tools.links`:
+
+```json5
+{
+  tools: {
+    links: {
+      enabled: true,
+      maxLinks: 3,
+      timeoutSeconds: 30,
+      scope: {
+        default: "allow",
+        rules: [{ action: "deny", match: { chatType: "group" } }]
+      },
+      models: [
+        {
+          command: "link-understand",
+          args: ["--url", "{{LinkUrl}}", "--format", "markdown"],
+          timeoutSeconds: 20
+        }
+      ]
+    }
+  }
+}
+```
+
+### `tools.links` fields
+
+- `enabled`: enable/disable link understanding (default: enabled when models are configured).
+- `maxLinks`: max URLs processed per message (default 3).
+- `timeoutSeconds`: default timeout for CLI runs (default 30).
+- `scope`: optional gating rules (same structure as media understanding scope).
+- `models`: ordered list of CLI entries (fallbacks in order).
+
+### Model entries (`tools.links.models[]`)
+
+Each entry is a CLI command:
+
+- `type`: optional, only `"cli"` is supported (default).
+- `command`: executable to run (required).
+- `args`: CLI args (templated; see **Template variables**).
+- `timeoutSeconds`: optional override for this entry.
+
+The first entry that returns **non-empty stdout** wins. If a command fails or
+returns empty output, Clawdbot tries the next entry.
+
+## Performance + ordering
+
+- Links are processed **sequentially** (per message, in order).
+- Each CLI entry has a timeout (per entry or default).
+- Failure to run a CLI does **not** abort the agent run; it just tries the next entry.
+- `maxLinks` is the primary cap for latency. Keep it low for chatty channels.
+
+## Template variables
+
+`tools.links.models[].args` supports the standard template variables plus `{{LinkUrl}}`.
+See [Template variables](/gateway/configuration#template-variables) for the full list.
+
+Link-specific variable:
+
+| Variable | Description |
+|----------|-------------|
+| `{{LinkUrl}}` | URL currently being processed |
+
+## Output format
+
+Each link is wrapped in a predictable envelope and appended to the message body:
+
+```
+<original message>
+
+[Link]
+URL: https://example.com
+Source: link-understand
+Summary:
+<cli output>
+```
+
+When multiple links are present, the header is numbered (`[Link 1/2]`, `[Link 2/2]`).
+`Source` is the CLI `command` that produced the output.
+
+### Output best practices
+
+- Keep summaries short and stable (avoid prompt bloat).
+- Prefer a compact, consistent structure (title → bullets → status).
+- Avoid surrounding fences unless you want the agent to treat it as literal text.
+
+
+## Scope gating
+
+`tools.links.scope` uses the same rules as media understanding:
+
+- `default`: `"allow"` or `"deny"`.
+- `rules[]`: first match wins.
+  - `match.channel` (surface/channel)
+  - `match.chatType` (`direct`, `group`, `channel`)
+  - `match.keyPrefix` (session key prefix)
+
+Example (only allow direct messages):
+
+```json5
+{
+  tools: {
+    links: {
+      scope: {
+        default: "deny",
+        rules: [{ action: "allow", match: { chatType: "direct" } }]
+      },
+      models: [{ command: "link-understand", args: ["--url", "{{LinkUrl}}"] }]
+    }
+  }
+}
+```
+
+## Security (SSRF guard)
+
+Clawdbot blocks local/private hosts before invoking your CLI. The guard rejects:
+
+- `localhost`, `*.localhost`, `*.local`, `*.internal`
+- Loopback addresses (IPv4 + IPv6)
+- Private and link-local IP ranges (IPv4 + IPv6)
+- `metadata.google.internal`
+- Addresses that resolve to private/internal IPs
+
+If a URL is blocked, it is **skipped** and your CLI is not invoked for it.
+URLs that fail DNS resolution are also skipped.
+
+## Decision tracking
+
+Each run records a decision payload (useful in logs/debugging) in `ctx.LinkUnderstandingDecisions`:
+
+```json5
+{
+  outcome: "success" | "skipped" | "disabled" | "scope-deny" | "no-links",
+  urls: [
+    {
+      url: "https://example.com",
+      attempts: [
+        { type: "cli", command: "link-understand", outcome: "success" }
+      ],
+      chosen: { type: "cli", command: "link-understand", outcome: "success" }
+    }
+  ]
+}
+```
+
+## Custom usage patterns
+
+### Ticket summarizer (single link)
+
+```json5
+{
+  tools: {
+    links: {
+      maxLinks: 1,
+      models: [
+        {
+          command: "ticket-summary",
+          args: ["--url", "{{LinkUrl}}", "--format", "brief"]
+        }
+      ]
+    }
+  }
+}
+```
+
+### Per-channel allowlist (only Discord + Slack)
+
+```json5
+{
+  tools: {
+    links: {
+      scope: {
+        default: "deny",
+        rules: [
+          { action: "allow", match: { channel: "discord" } },
+          { action: "allow", match: { channel: "slack" } }
+        ]
+      },
+      models: [{ command: "link-understand", args: ["--url", "{{LinkUrl}}"] }]
+    }
+  }
+}
+```
+
+### Per-agent override (support agent only)
+
+```json5
+{
+  agents: {
+    list: [
+      {
+        id: "support",
+        tools: {
+          links: {
+            enabled: true,
+            maxLinks: 2,
+            models: [{ command: "link-understand", args: ["--url", "{{LinkUrl}}"] }]
+          }
+        }
+      }
+    ]
+  }
+}
+```
+
+### Markdown link behavior (ignored)
+
+Message:
+```
+Please check [our docs](https://docs.example.com) and https://status.example.com
+```
+
+Only `https://status.example.com` is processed (markdown links are stripped).
+
+## Troubleshooting
+
+- **Nothing happens:** ensure `tools.links.models` is set and `enabled` is not `false`.
+- **No links detected:** only bare URLs are extracted; markdown links are ignored.
+- **Output missing:** your CLI returned empty stdout; try logging or return a default line.
+- **Wrong channel scope:** check `tools.links.scope` rules and `match.chatType`.
+- **SSRF blocked:** local/private URLs are skipped by design.
+
+Enable verbose logs to see CLI execution and scope decisions:
+
+```bash
+clawdbot gateway run --verbose
+```
+
+## Examples
+
+### Minimal CLI runner
+
+```json5
+{
+  tools: {
+    links: {
+      models: [{ command: "link-understand", args: ["--url", "{{LinkUrl}}"] }]
+    }
+  }
+}
+```
+
+### Limit to 1 link, custom timeout
+
+```json5
+{
+  tools: {
+    links: {
+      maxLinks: 1,
+      timeoutSeconds: 10,
+      models: [{ command: "link-understand", args: ["--url", "{{LinkUrl}}"] }]
+    }
+  }
+}
+```
+
+### Fallback chain (first non-empty output wins)
+
+```json5
+{
+  tools: {
+    links: {
+      models: [
+        { command: "link-understand", args: ["--url", "{{LinkUrl}}"] },
+        { command: "link-backup", args: ["{{LinkUrl}}"] }
+      ]
+    }
+  }
+}
+```

src/auto-reply/templating.ts

@@ -5,6 +5,7 @@ import type {
   MediaUnderstandingDecision,
   MediaUnderstandingOutput,
 } from "../media-understanding/types.js";
+import type { LinkUnderstandingDecision } from "../link-understanding/types.js";
 
 /** Valid message channels for routing. */
 export type OriginatingChannelType = ChannelId | InternalMessageChannel;
@@ -72,6 +73,7 @@ export type MsgContext = {
   MediaUnderstanding?: MediaUnderstandingOutput[];
   MediaUnderstandingDecisions?: MediaUnderstandingDecision[];
   LinkUnderstanding?: string[];
+  LinkUnderstandingDecisions?: LinkUnderstandingDecision[];
   Prompt?: string;
   MaxChars?: number;
   ChatType?: string;

src/channels/plugins/group-mentions.ts

@@ -240,6 +240,17 @@ export function resolveIMessageGroupToolPolicy(
   });
 }
 
+export function resolveGoogleChatGroupToolPolicy(
+  params: GroupMentionParams,
+): GroupToolPolicyConfig | undefined {
+  return resolveChannelGroupToolsPolicy({
+    cfg: params.cfg,
+    channel: "googlechat",
+    groupId: params.groupId,
+    accountId: params.accountId,
+  });
+}
+
 export function resolveDiscordGroupToolPolicy(
   params: GroupMentionParams,
 ): GroupToolPolicyConfig | undefined {

src/gateway/server-methods/chat.ts

@@ -14,8 +14,6 @@ import {
   type ResponsePrefixContext,
 } from "../../auto-reply/reply/response-prefix-template.js";
 import type { MsgContext } from "../../auto-reply/templating.js";
-import { formatLinkUnderstandingBody } from "../../link-understanding/format.js";
-import { runLinkUnderstanding } from "../../link-understanding/runner.js";
 import { resolveSendPolicy } from "../../sessions/send-policy.js";
 import { INTERNAL_MESSAGE_CHANNEL } from "../../utils/message-channel.js";
 import {
@@ -414,31 +412,6 @@ export const chatHandlers: GatewayRequestHandlers = {
       return;
     }
 
-    try {
-      const linkCtx: MsgContext = {
-        Body: parsedMessage,
-        RawBody: parsedMessage,
-        CommandBody: parsedMessage,
-        SessionKey: p.sessionKey,
-        ChatType: entry?.chatType,
-        Surface: entry?.channel ?? "webchat",
-      };
-      const linkResult = await runLinkUnderstanding({
-        cfg,
-        ctx: linkCtx,
-        message: parsedMessage,
-      });
-      if (linkResult.outputs.length > 0) {
-        parsedMessage = formatLinkUnderstandingBody({
-          body: parsedMessage,
-          outputs: linkResult.outputs,
-        });
-      }
-    } catch (err) {
-      respond(false, undefined, errorShape(ErrorCodes.UNAVAILABLE, String(err)));
-      return;
-    }
-
     try {
       const abortController = new AbortController();
       context.chatAbortControllers.set(clientRunId, {

src/link-understanding/apply.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it, vi } from "vitest";
+
+import type { ClawdbotConfig } from "../config/config.js";
+import type { MsgContext } from "../auto-reply/templating.js";
+import { runLinkUnderstanding } from "./runner.js";
+
+vi.mock("./runner.js", () => ({
+  runLinkUnderstanding: vi.fn(),
+}));
+
+describe("applyLinkUnderstanding", () => {
+  it("keeps command parsing bodies unchanged when link output is applied", async () => {
+    const mockedRunLinkUnderstanding = vi.mocked(runLinkUnderstanding);
+    mockedRunLinkUnderstanding.mockResolvedValue({
+      urls: ["https://example.com"],
+      outputs: [{ url: "https://example.com", text: "Summary", source: "link-cli" }],
+      decisions: [],
+    });
+
+    const { applyLinkUnderstanding } = await import("./apply.js");
+    const ctx: MsgContext = {
+      Body: "check https://example.com",
+      RawBody: "raw override",
+      CommandBody: "/think low check https://example.com",
+    };
+    const cfg: ClawdbotConfig = {
+      tools: { links: { models: [{ command: "link-cli" }] } },
+    };
+
+    await applyLinkUnderstanding({ ctx, cfg });
+
+    expect(ctx.Body).toContain("[Link]");
+    expect(ctx.CommandBody).toBe("/think low check https://example.com");
+    expect(ctx.RawBody).toBe("raw override");
+    expect(ctx.BodyForCommands).toBe("/think low check https://example.com");
+    expect(ctx.BodyForCommands).not.toContain("[Link]");
+  });
+
+  it("preserves original body for command parsing when no overrides exist", async () => {
+    const mockedRunLinkUnderstanding = vi.mocked(runLinkUnderstanding);
+    mockedRunLinkUnderstanding.mockResolvedValue({
+      urls: ["https://example.com"],
+      outputs: [{ url: "https://example.com", text: "Summary", source: "link-cli" }],
+      decisions: [],
+    });
+
+    const { applyLinkUnderstanding } = await import("./apply.js");
+    const ctx: MsgContext = {
+      Body: "check https://example.com",
+    };
+    const cfg: ClawdbotConfig = {
+      tools: { links: { models: [{ command: "link-cli" }] } },
+    };
+
+    await applyLinkUnderstanding({ ctx, cfg });
+
+    expect(ctx.Body).toContain("[Link]");
+    expect(ctx.RawBody).toBe("check https://example.com");
+    expect(ctx.BodyForCommands).toBe("check https://example.com");
+  });
+});

src/link-understanding/apply.ts

@@ -1,12 +1,14 @@
 import type { ClawdbotConfig } from "../config/config.js";
 import type { MsgContext } from "../auto-reply/templating.js";
 import { finalizeInboundContext } from "../auto-reply/reply/inbound-context.js";
-import { formatLinkUnderstandingBody } from "./format.js";
+import { formatLinkUnderstandingBody, formatLinkUnderstandingSections } from "./format.js";
 import { runLinkUnderstanding } from "./runner.js";
+import type { LinkUnderstandingDecision, LinkUnderstandingOutput } from "./types.js";
 
 export type ApplyLinkUnderstandingResult = {
-  outputs: string[];
+  outputs: LinkUnderstandingOutput[];
   urls: string[];
+  decisions: LinkUnderstandingDecision[];
 };
 
 export async function applyLinkUnderstanding(params: {
@@ -18,16 +20,29 @@ export async function applyLinkUnderstanding(params: {
     ctx: params.ctx,
   });
 
+  if (result.decisions.length > 0) {
+    params.ctx.LinkUnderstandingDecisions = [
+      ...(params.ctx.LinkUnderstandingDecisions ?? []),
+      ...result.decisions,
+    ];
+  }
+
   if (result.outputs.length === 0) {
     return result;
   }
 
-  params.ctx.LinkUnderstanding = [...(params.ctx.LinkUnderstanding ?? []), ...result.outputs];
+  const originalBody = params.ctx.Body;
+  const sections = formatLinkUnderstandingSections(result.outputs);
+  if (sections.length > 0) {
+    params.ctx.LinkUnderstanding = [...(params.ctx.LinkUnderstanding ?? []), ...sections];
+  }
   params.ctx.Body = formatLinkUnderstandingBody({
     body: params.ctx.Body,
     outputs: result.outputs,
   });
-
+  if (!params.ctx.CommandBody && !params.ctx.RawBody && typeof originalBody === "string") {
+    params.ctx.RawBody = originalBody;
+  }
   finalizeInboundContext(params.ctx, {
     forceBodyForAgent: true,
     forceBodyForCommands: true,

src/link-understanding/detect.test.ts

@@ -20,8 +20,10 @@ describe("extractLinksFromMessage", () => {
     expect(links).toEqual(["https://bare.example"]);
   });
 
-  it("blocks localhost", () => {
-    const links = extractLinksFromMessage("http://127.0.0.1/test https://ok.test");
+  it("blocks loopback and private hosts", () => {
+    const links = extractLinksFromMessage(
+      "http://localhost/test http://127.0.0.1/test http://[::1]/test http://10.0.0.1/test https://ok.test",
+    );
     expect(links).toEqual(["https://ok.test"]);
   });
 });

src/link-understanding/detect.ts

@@ -1,3 +1,4 @@
+import { isBlockedHostname, isPrivateIpAddress } from "../infra/net/ssrf.js";
 import { DEFAULT_MAX_LINKS } from "./defaults.js";
 
 // Remove markdown link syntax so only bare URLs are considered.
@@ -19,7 +20,10 @@ function isAllowedUrl(raw: string): boolean {
   try {
     const parsed = new URL(raw);
     if (parsed.protocol !== "http:" && parsed.protocol !== "https:") return false;
-    if (parsed.hostname === "127.0.0.1") return false;
+    const hostname = parsed.hostname;
+    if (!hostname) return false;
+    if (isBlockedHostname(hostname)) return false;
+    if (isPrivateIpAddress(hostname)) return false;
     return true;
   } catch {
     return false;

src/link-understanding/format.test.ts

@@ -0,0 +1,27 @@
+import { describe, expect, it } from "vitest";
+
+import { formatLinkUnderstandingBody } from "./format.js";
+
+describe("formatLinkUnderstandingBody", () => {
+  it("appends a structured link summary with source", () => {
+    const body = formatLinkUnderstandingBody({
+      body: "Check this",
+      outputs: [{ url: "https://example.com", text: "Summary here", source: "link-cli" }],
+    });
+    expect(body).toBe(
+      "Check this\n\n[Link]\nURL: https://example.com\nSource: link-cli\nSummary:\nSummary here",
+    );
+  });
+
+  it("numbers multiple links and omits empty body", () => {
+    const body = formatLinkUnderstandingBody({
+      outputs: [
+        { url: "https://a.example", text: "First", source: "cli-a" },
+        { url: "https://b.example", text: "Second", source: "cli-b" },
+      ],
+    });
+    expect(body).toBe(
+      "[Link 1/2]\nURL: https://a.example\nSource: cli-a\nSummary:\nFirst\n\n[Link 2/2]\nURL: https://b.example\nSource: cli-b\nSummary:\nSecond",
+    );
+  });
+});

src/link-understanding/format.ts

@@ -1,10 +1,31 @@
-export function formatLinkUnderstandingBody(params: { body?: string; outputs: string[] }): string {
-  const outputs = params.outputs.map((output) => output.trim()).filter(Boolean);
-  if (outputs.length === 0) {
+import type { LinkUnderstandingOutput } from "./types.js";
+
+function formatSection(output: LinkUnderstandingOutput, index: number, total: number): string {
+  const label = total > 1 ? `Link ${index + 1}/${total}` : "Link";
+  const source = output.source?.trim() || "unknown";
+  const lines = [`[${label}]`, `URL: ${output.url}`, `Source: ${source}`];
+  lines.push(`Summary:\n${output.text.trim()}`);
+  return lines.join("\n");
+}
+
+export function formatLinkUnderstandingSections(outputs: LinkUnderstandingOutput[]): string[] {
+  const trimmed = outputs
+    .map((output) => ({ ...output, text: output.text.trim(), url: output.url.trim() }))
+    .filter((output) => output.text && output.url);
+  if (trimmed.length === 0) return [];
+  return trimmed.map((output, index) => formatSection(output, index, trimmed.length));
+}
+
+export function formatLinkUnderstandingBody(params: {
+  body?: string;
+  outputs: LinkUnderstandingOutput[];
+}): string {
+  const sections = formatLinkUnderstandingSections(params.outputs);
+  if (sections.length === 0) {
     return params.body ?? "";
   }
 
   const base = (params.body ?? "").trim();
-  if (!base) return outputs.join("\n");
-  return `${base}\n\n${outputs.join("\n")}`;
+  if (!base) return sections.join("\n\n");
+  return `${base}\n\n${sections.join("\n\n")}`;
 }

src/link-understanding/index.ts

@@ -2,3 +2,10 @@ export { applyLinkUnderstanding } from "./apply.js";
 export { extractLinksFromMessage } from "./detect.js";
 export { formatLinkUnderstandingBody } from "./format.js";
 export { runLinkUnderstanding } from "./runner.js";
+export type {
+  LinkUnderstandingDecision,
+  LinkUnderstandingDecisionOutcome,
+  LinkUnderstandingModelDecision,
+  LinkUnderstandingOutput,
+  LinkUnderstandingUrlDecision,
+} from "./types.js";

src/link-understanding/runner.test.ts

@@ -0,0 +1,84 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+import type { MsgContext } from "../auto-reply/templating.js";
+import type { ClawdbotConfig } from "../config/config.js";
+import { assertPublicHostname } from "../infra/net/ssrf.js";
+import { runExec } from "../process/exec.js";
+
+vi.mock("../process/exec.js", () => ({
+  runExec: vi.fn(),
+}));
+vi.mock("../infra/net/ssrf.js", async () => {
+  const actual =
+    await vi.importActual<typeof import("../infra/net/ssrf.js")>("../infra/net/ssrf.js");
+  return {
+    ...actual,
+    assertPublicHostname: vi.fn(),
+  };
+});
+
+async function loadRunner() {
+  return await import("./runner.js");
+}
+
+describe("runLinkUnderstanding", () => {
+  const mockedRunExec = vi.mocked(runExec);
+  const mockedAssertPublicHostname = vi.mocked(assertPublicHostname);
+
+  beforeEach(() => {
+    mockedRunExec.mockReset();
+    mockedAssertPublicHostname.mockReset();
+    mockedAssertPublicHostname.mockResolvedValue(undefined);
+  });
+
+  it("falls back to the next model when a CLI entry fails", async () => {
+    const { runLinkUnderstanding } = await loadRunner();
+    mockedRunExec.mockImplementation(async (command) => {
+      if (command === "fail") throw new Error("boom");
+      return { stdout: "summary", stderr: "" };
+    });
+
+    const cfg: ClawdbotConfig = {
+      tools: {
+        links: {
+          enabled: true,
+          models: [{ command: "fail" }, { command: "ok" }],
+        },
+      },
+    };
+    const ctx: MsgContext = {
+      Body: "see https://example.com",
+      SessionKey: "session-1",
+      Surface: "discord",
+      ChatType: "direct",
+    };
+
+    const result = await runLinkUnderstanding({ cfg, ctx });
+    expect(result.urls).toEqual(["https://example.com"]);
+    expect(result.outputs).toEqual([{ url: "https://example.com", text: "summary", source: "ok" }]);
+  });
+
+  it("skips links that fail the public hostname check", async () => {
+    const { runLinkUnderstanding } = await loadRunner();
+    mockedAssertPublicHostname.mockRejectedValueOnce(new Error("Blocked: private/internal IP"));
+
+    const cfg: ClawdbotConfig = {
+      tools: {
+        links: {
+          enabled: true,
+          models: [{ command: "ok" }],
+        },
+      },
+    };
+    const ctx: MsgContext = {
+      Body: "see https://intranet.example.com",
+      SessionKey: "session-1",
+      Surface: "discord",
+      ChatType: "direct",
+    };
+
+    const result = await runLinkUnderstanding({ cfg, ctx });
+    expect(result.outputs).toEqual([]);
+    expect(result.decisions[0]?.urls[0]?.attempts[0]?.reason).toContain("Blocked");
+  });
+});

src/link-understanding/runner.ts

@@ -10,12 +10,20 @@ import {
   normalizeMediaUnderstandingChatType,
   resolveMediaUnderstandingScope,
 } from "../media-understanding/scope.js";
+import { assertPublicHostname } from "../infra/net/ssrf.js";
 import { DEFAULT_LINK_TIMEOUT_SECONDS } from "./defaults.js";
 import { extractLinksFromMessage } from "./detect.js";
+import type {
+  LinkUnderstandingDecision,
+  LinkUnderstandingModelDecision,
+  LinkUnderstandingOutput,
+  LinkUnderstandingUrlDecision,
+} from "./types.js";
 
 export type LinkUnderstandingResult = {
   urls: string[];
-  outputs: string[];
+  outputs: LinkUnderstandingOutput[];
+  decisions: LinkUnderstandingDecision[];
 };
 
 function resolveScopeDecision(params: {
@@ -69,12 +77,42 @@ async function runCliEntry(params: {
   return trimmed || null;
 }
 
+function buildModelDecision(params: {
+  entry: LinkModelConfig;
+  outcome: LinkUnderstandingModelDecision["outcome"];
+  reason?: string;
+}): LinkUnderstandingModelDecision {
+  const command = params.entry.command?.trim();
+  return {
+    type: "cli",
+    command: command || undefined,
+    outcome: params.outcome,
+    reason: params.reason,
+  };
+}
+
+async function assertUrlIsPublic(
+  url: string,
+): Promise<{ ok: true } | { ok: false; reason: string }> {
+  try {
+    const parsed = new URL(url);
+    await assertPublicHostname(parsed.hostname);
+    return { ok: true };
+  } catch (err) {
+    return { ok: false, reason: String(err) };
+  }
+}
+
 async function runLinkEntries(params: {
   entries: LinkModelConfig[];
   ctx: MsgContext;
   url: string;
   config?: LinkToolsConfig;
-}): Promise<string | null> {
+}): Promise<{
+  output: LinkUnderstandingOutput | null;
+  attempts: LinkUnderstandingModelDecision[];
+}> {
+  const attempts: LinkUnderstandingModelDecision[] = [];
   for (const entry of params.entries) {
     try {
       const output = await runCliEntry({
@@ -83,12 +121,33 @@ async function runLinkEntries(params: {
         url: params.url,
         config: params.config,
       });
-      if (output) return output;
+      if (output) {
+        const decision = buildModelDecision({ entry, outcome: "success" });
+        attempts.push(decision);
+        return {
+          output: {
+            url: params.url,
+            text: output,
+            source: entry.command?.trim() || undefined,
+          },
+          attempts,
+        };
+      }
+      attempts.push(buildModelDecision({ entry, outcome: "skipped", reason: "empty output" }));
     } catch (err) {
-      throw new Error(`link processor failed for ${params.url}: ${String(err)}`);
+      if (shouldLogVerbose()) {
+        logVerbose(`Link understanding failed for ${params.url}: ${String(err)}`);
+      }
+      attempts.push(
+        buildModelDecision({
+          entry,
+          outcome: "failed",
+          reason: String(err),
+        }),
+      );
     }
   }
-  return null;
+  return { output: null, attempts };
 }
 
 export async function runLinkUnderstanding(params: {
@@ -97,33 +156,66 @@ export async function runLinkUnderstanding(params: {
   message?: string;
 }): Promise<LinkUnderstandingResult> {
   const config = params.cfg.tools?.links;
-  if (!config || config.enabled === false) return { urls: [], outputs: [] };
+  if (!config || config.enabled === false) {
+    return { urls: [], outputs: [], decisions: [{ outcome: "disabled", urls: [] }] };
+  }
 
   const scopeDecision = resolveScopeDecision({ config, ctx: params.ctx });
   if (scopeDecision === "deny") {
     if (shouldLogVerbose()) {
       logVerbose("Link understanding disabled by scope policy.");
     }
-    return { urls: [], outputs: [] };
+    return { urls: [], outputs: [], decisions: [{ outcome: "scope-deny", urls: [] }] };
   }
 
   const message = params.message ?? params.ctx.CommandBody ?? params.ctx.RawBody ?? params.ctx.Body;
   const links = extractLinksFromMessage(message ?? "", { maxLinks: config?.maxLinks });
-  if (links.length === 0) return { urls: [], outputs: [] };
+  if (links.length === 0) {
+    return { urls: [], outputs: [], decisions: [{ outcome: "no-links", urls: [] }] };
+  }
 
   const entries = config?.models ?? [];
-  if (entries.length === 0) return { urls: links, outputs: [] };
+  if (entries.length === 0) {
+    const urlDecisions: LinkUnderstandingUrlDecision[] = links.map((url) => ({
+      url,
+      attempts: [],
+    }));
+    return {
+      urls: links,
+      outputs: [],
+      decisions: [{ outcome: "skipped", urls: urlDecisions }],
+    };
+  }
 
-  const outputs: string[] = [];
+  const outputs: LinkUnderstandingOutput[] = [];
+  const urlDecisions: LinkUnderstandingUrlDecision[] = [];
   for (const url of links) {
-    const output = await runLinkEntries({
+    const ssrfCheck = await assertUrlIsPublic(url);
+    if (!ssrfCheck.ok) {
+      urlDecisions.push({
+        url,
+        attempts: [
+          {
+            type: "cli",
+            command: "ssrf",
+            outcome: "skipped",
+            reason: ssrfCheck.reason,
+          },
+        ],
+      });
+      continue;
+    }
+    const { output, attempts } = await runLinkEntries({
       entries,
       ctx: params.ctx,
       url,
       config,
     });
+    const chosen = attempts.find((attempt) => attempt.outcome === "success");
+    urlDecisions.push({ url, attempts, chosen });
     if (output) outputs.push(output);
   }
 
-  return { urls: links, outputs };
+  const outcome = outputs.length > 0 ? "success" : "skipped";
+  return { urls: links, outputs, decisions: [{ outcome, urls: urlDecisions }] };
 }

src/link-understanding/types.ts

@@ -0,0 +1,30 @@
+export type LinkUnderstandingOutput = {
+  url: string;
+  text: string;
+  source?: string;
+};
+
+export type LinkUnderstandingModelDecision = {
+  type: "cli";
+  command?: string;
+  outcome: "success" | "skipped" | "failed";
+  reason?: string;
+};
+
+export type LinkUnderstandingUrlDecision = {
+  url: string;
+  attempts: LinkUnderstandingModelDecision[];
+  chosen?: LinkUnderstandingModelDecision;
+};
+
+export type LinkUnderstandingDecisionOutcome =
+  | "success"
+  | "skipped"
+  | "disabled"
+  | "scope-deny"
+  | "no-links";
+
+export type LinkUnderstandingDecision = {
+  outcome: LinkUnderstandingDecisionOutcome;
+  urls: LinkUnderstandingUrlDecision[];
+};