How AIN Bridge works

The problem: 480+ tools, no wiring

Each AINumbers tool is a fully self-contained HTML page with its own inputs and its own computed outputs. That is the security guarantee — no cross-page data leakage, no shared state, no server that could log your inputs. But it creates an integration gap: when an agent wants to chain tools, or when a user finishes one tool and needs to carry its outputs into the next, who does the hand-off?

AIN Bridge is the answer. It runs inside each tool's browser context — never on a server — and provides three channels through which inputs can be populated from the outside world: a URL hash fragment, a JSON file, or a parent frame's postMessage.

Prefill Deep-link URL encoding

The simplest Bridge capability: encode a JSON object of {elementId: value} pairs as base64url, append it to a tool URL as #in=<encoded>, and share the link. When the tool loads in the browser, the Bridge decodes the fragment, fills each matching input, and shows a confirmation notice. Adding &run=1 opts into auto-execution — the tool runs immediately after filling.

This is the mechanism agents use to hand off context to users in a zero-PII way. The encoded data never leaves the browser — the hash fragment is not sent to any server in HTTP requests. The tool URL and its inputs are the only things that cross the wire.

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Intake Policy Mandate import zone

When a tool is configured with intake: true, the Bridge renders a drop zone above the first panel. Users can drag-and-drop a .policy.json file produced by any prior tool, choose one from disk, or paste raw JSON. The Bridge validates the mandate structure, then maps its payload and source_tool_inputs fields onto matching DOM element IDs — the same mechanism as prefill, but driven by the mandate file rather than a URL.

This is how chaining works in practice. Tool A exports a Policy Mandate. The user opens Tool B. They drop the .policy.json into the intake zone. Relevant fields auto-fill. No copy-pasting, no manual transcription, no re-entry errors.

{
  "mandate_id": "mnd_20260618_T503_abc123",
  "tool_id": "503-canton-tokenization-readiness-diagnostic",
  "tool_version": "1.0.0",
  "issued_at": "2026-06-18T14:30:00Z",
  "payload": {
    /* keys = element IDs in the RECEIVING tool */
    "entityName": "Apex Clearing Corp",
    "domicile": "US"
  },
  "source_tool_inputs": {
    /* the sending tool's own inputs, for audit trail */
    "entityType": "clearing_member"
  },
  "execution_hash": "a3f8c2…"  /* SHA-256 of sorted canonical JSON */
}

Messaging Composer postMessage protocol

Composer pages (e.g. guides/aml-programme-composer.html) load tools in <iframe> elements. AIN Bridge listens for window.message events from a same-origin parent and responds to three message types. This lets a composer pre-fill a tool, trigger its run function, and collect the resulting Policy Mandate — all without any server round-trip.

Same-origin enforcement is strict: the Bridge checks e.source === window.parent and, where available, verifies e.origin === location.origin. Cross-origin composers cannot drive tools.

Security posture

AIN Bridge was designed with a strict contract: it can connect tools without creating new attack surfaces. Every design decision — from how values are applied to when functions are invoked — is constrained to prevent injection, data exfiltration, and cross-origin abuse.

Adding the Bridge to a tool

Each tool carries one configuration line declaring its Bridge options, followed by the shared Bridge script. The snippet is inserted before </body> by scripts/fix_bridge_t.py during builds. For manual integration:

<!-- 1. Declare config before the Bridge script -->
<script>window.AIN_BRIDGE_CFG = {
  runFn:        "runMyTool",   // global function name; null = no auto-run
  intake:       true,          // show Policy Mandate drop zone?
  intakeTarget: "mandateInput", // textarea id for full JSON paste (optional)
  intakeAnchor: ".pii-notice"  // CSS selector — drop zone inserts before this
};</script>

<!-- 2. Bridge script (minified, from scripts/ain-bridge-v1.snippet.html) -->
<script>(function(){ /* … bridge code … */ })();</script>

Public API — window.AINBridge

Once the Bridge boots, these methods are available to tool code for programmatic use: