we now spy keyblocks for spends, need to test but probably close to working

wip
grids random payload defined
2026-03-02 18:54:33 -08:00 · 2026-03-02 18:27:05 -08:00 · 2026-02-27 11:43:33 -08:00 · 2026-02-27 11:34:33 -08:00 · 2026-02-25 18:22:26 -08:00 · 2025-12-30 11:45:25 -08:00
19 changed files with 1532 additions and 7 deletions
@@ -1,3 +1,9 @@
+2026-02-25(PRH):
+    grids: instead of spying the chain for a tx, let's use dead drop
+
+    - so for "generate", need to form tx for the user to sign
+    - make dead drop -> have process that knows each tx and the dead drop location
+
 OPEN LOOPS - 2025-11-12
    - websockets
        - separate websocket handling from websocket parsing/sending
@@ -1,9 +1,43 @@
-# fewd = front end web dev
+fewd = front end web dev
+=====================================================================

 this is me (PRH) trying to learn some front end web dev because pixels are
 important despite my wishes.

-# notes
+Building/Running
+---------------------------------------------------------------------

-## goal queue
+### Prereqs

+1. [Install Erlang and ZX](https://git.qpq.swiss/QPQ-AG/research-megadoc/wiki/Installing-Erlang-and-zx)
+2. **DEV ONLY**: `apt install node-typescript` (Devuan Excalibur)
+
+   This is needed if you want to **edit** the `.ts` files found in
+   `/priv/static/js/ts/*.ts`. The built JS files are under version control and can
+   be found in `/priv/static/js/dist/`
+
+### Building/Running HTTP Server
+
+If you are only changing the Erlang or simply just want to run the program
+without developing it, then just run
+
+```
+zxh runlocal
+```
+
+### Building TS->JS
+
+**This is only necessary if you edited the `.ts` files and want to transpile
+them over to JS.**
+
+This requires you installed `tsc` as above.
+
+```
+make tsc
+```
+
+If you're doing development you may want
+
+```
+make watch
+```
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="utf-8">
+    <title>FIXME</title>
+    <link rel="stylesheet" href="/css/default.css">
+</head>
+<body>
+    <div id="titlebar">
+        <div class="content">
+            <a href="/" class="tb-home">Home</a>
+        </div>
+    </div>
+
+    <div class="content">
+        <h1 class="content-title">FEWD: FIXME</h1>
+
+    </div>
+</body>
+</html>
@@ -0,0 +1,9 @@
+/**
+ * Title:           Title
+ * Description:     Description
+ * Author:          Peter Harpending <peterharpending@qpq.swiss>
+ * Date:            YYYY-MM-DD
+ * Last-Updated:    YYYY-MM-DD
+ *
+ * @module
+ */
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="utf-8">
+    <title>Basic GRIDS Demo</title>
+    <link rel="stylesheet" href="/css/default.css">
+</head>
+<body>
+    <div id="titlebar">
+        <div class="content">
+            <a href="/" class="tb-home">Home</a>
+        </div>
+    </div>
+
+    <div class="content">
+        <h1 class="content-title">FEWD: GRIDS DEMO</h1>
+
+
+        <h2>Making a Spend</h2>
+
+        <label for="grids-n">Network ID:</label>
+        <input type  = "text"
+               id    = "grids-n"
+               value = "groot.testnet"
+               disabled>
+        <br>
+
+        <label for="grids-r">Recipient:</label>
+        <input type  = "text"
+               id    = "grids-r"
+               value = "ak_n6aVQ6PkBdVdv7kRRcfnzDVmBsH6hqEwVWSB6UAEb3kkjrPMe"
+               disabled>
+        <br>
+
+        <label for="grids-a">Amount (P):</label>
+        <input type  = "number"
+               id    = "grids-a"
+               value = "69"
+               disabled>
+        <br>
+
+        <label for="grids-p">Payload:</label>
+        <input type  = "text"
+               id    = "grids-p"
+               disabled>
+        <br>
+
+        <input type  = "button"
+               id    = "grids-submit"
+               value = "Generate">
+        <br>
+
+        <textarea disabled id="grids-url" hidden></textarea>
+        <br>
+        <img id="grids-png" hidden>
+    </div>
+
+    <script src="/js/dist/grids-basic.js"></script>
+</body>
+</html>
@@ -17,6 +17,7 @@

        <ul>
            <li><a href="/echo.html">Echo</a></li>
+            <li><a href="/grids-basic.html">GRIDS: Basic Demo</a></li>
            <li><a href="/wfc.html">WFC</a></li>
        </ul>
    </div>
@@ -0,0 +1,29 @@
+/**
+ * Title:           GRIDS Basic Page Script
+ * Description:     Page Script for /grids-basic.html
+ * Author:          Peter Harpending <peterharpending@qpq.swiss>
+ * Date:            2025-12-29
+ * Last-Updated:    2025-12-29
+ *
+ * @module
+ */
+/**
+ * Runs on page load
+ */
+declare function main(): Promise<void>;
+declare function on_submit(n_input: HTMLInputElement, r_input: HTMLInputElement, a_input: HTMLInputElement, p_input: HTMLInputElement, grids_url_elt: HTMLTextAreaElement, grids_png_elt: HTMLImageElement): Promise<void>;
+type Safe<t> = {
+    ok: true;
+    result: t;
+} | {
+    ok: false;
+    error: string;
+};
+type GridsResult = {
+    url: string;
+    png_base64: string;
+};
+/**
+ * gets the grids url
+ */
+declare function grids_request(net_id: string, recipient: string, amount: number, payload: string): Promise<Safe<GridsResult>>;
@@ -0,0 +1,87 @@
+"use strict";
+/**
+ * Title:           GRIDS Basic Page Script
+ * Description:     Page Script for /grids-basic.html
+ * Author:          Peter Harpending <peterharpending@qpq.swiss>
+ * Date:            2025-12-29
+ * Last-Updated:    2025-12-29
+ *
+ * @module
+ */
+main();
+/**
+ * Runs on page load
+ */
+async function main() {
+    let n_input = document.getElementById('grids-n');
+    let r_input = document.getElementById('grids-r');
+    let a_input = document.getElementById('grids-a');
+    let p_input = document.getElementById('grids-p');
+    let submit_btn = document.getElementById('grids-submit');
+    let grids_url_elt = document.getElementById('grids-url');
+    let grids_png_elt = document.getElementById('grids-png');
+    let rand_data = new Uint8Array(32);
+    window.crypto.getRandomValues(rand_data);
+    let hex = rand_data.toHex().toUpperCase();
+    p_input.value = 'text payload ' + hex;
+    // Page initialization
+    submit_btn.addEventListener('click', async function (e) {
+        await on_submit(n_input, r_input, a_input, p_input, grids_url_elt, grids_png_elt);
+    });
+    // enable buttons
+    submit_btn.disabled = false;
+}
+async function on_submit(n_input, r_input, a_input, p_input, grids_url_elt, grids_png_elt) {
+    // pull out values
+    let network_id = n_input.value;
+    let recipient = r_input.value;
+    let amount = parseInt(a_input.value);
+    let payload = p_input.value;
+    let result = await grids_request(network_id, recipient, amount, payload);
+    // show url field and png
+    if (result.ok) {
+        let url = result.result.url;
+        let png_base64 = result.result.png_base64;
+        let src_prefix = 'data:image/png;base64,';
+        let src = src_prefix + png_base64;
+        grids_url_elt.innerText = url;
+        grids_png_elt.src = src;
+        grids_url_elt.hidden = false;
+        grids_png_elt.hidden = false;
+    }
+    else {
+        alert('ERROR: ' + result.error);
+    }
+}
+/**
+ * gets the grids url
+ */
+async function grids_request(net_id, recipient, amount, payload) {
+    // format for network transmission
+    let obj = { 'network_id': net_id,
+        'recipient': recipient,
+        'amount': amount,
+        'payload': payload };
+    let obj_text = JSON.stringify(obj, undefined, 4);
+    let url = '/grids-mkdd';
+    let req_options = { method: 'POST',
+        headers: { 'content-type': 'application/json' },
+        body: obj_text };
+    let result = { ok: false,
+        error: 'IT DO BE LIKE THAT MISTA STANCIL' };
+    try {
+        let response = await fetch(url, req_options);
+        if (response.ok)
+            result = await response.json();
+        else {
+            console.log('bad http response:', response);
+            result = { ok: false, error: 'BAD HTTP RESPONSE' };
+        }
+    }
+    catch (x) {
+        console.log('network error:', x);
+        result = { ok: false, error: 'NETWORK ERROR' };
+    }
+    return result;
+}
+//# sourceMappingURL=grids-basic.js.map
@@ -0,0 +1 @@
+{"version":3,"file":"grids-basic.js","sourceRoot":"","sources":["../ts/grids-basic.ts"],"names":[],"mappings":";AAAA;;;;;;;;GAQG;AAEH,IAAI,EAAE,CAAC;AAGP;;GAEG;AACH,KAAK,UACL,IAAI;IAGA,IAAI,OAAO,GAAM,QAAQ,CAAC,cAAc,CAAC,SAAS,CAA0B,CAAC;IAC7E,IAAI,OAAO,GAAM,QAAQ,CAAC,cAAc,CAAC,SAAS,CAA0B,CAAC;IAC7E,IAAI,OAAO,GAAM,QAAQ,CAAC,cAAc,CAAC,SAAS,CAA0B,CAAC;IAC7E,IAAI,OAAO,GAAM,QAAQ,CAAC,cAAc,CAAC,SAAS,CAA0B,CAAC;IAC7E,IAAI,UAAU,GAAG,QAAQ,CAAC,cAAc,CAAC,cAAc,CAAqB,CAAC;IAE7E,IAAI,aAAa,GAAG,QAAQ,CAAC,cAAc,CAAC,WAAW,CAAwB,CAAC;IAChF,IAAI,aAAa,GAAG,QAAQ,CAAC,cAAc,CAAC,WAAW,CAAqB,CAAC;IAE7E,IAAI,SAAS,GAAgB,IAAI,UAAU,CAAC,EAAE,CAAC,CAAC;IAChD,MAAM,CAAC,MAAM,CAAC,eAAe,CAAC,SAAS,CAAC,CAAC;IACzC,IAAI,GAAG,GAAY,SAAS,CAAC,KAAK,EAAE,CAAC,WAAW,EAAE,CAAC;IACnD,OAAO,CAAC,KAAK,GAAG,eAAe,GAAG,GAAG,CAAC;IAEtC,sBAAsB;IACtB,UAAU,CAAC,gBAAgB,CACvB,OAAO,EACP,KAAK,WAAU,CAAC;QACZ,MAAM,SAAS,CAAC,OAAO,EAAE,OAAO,EAAE,OAAO,EAAE,OAAO,EAAE,aAAa,EAAE,aAAa,CAAC,CAAA;IACrF,CAAC,CACJ,CAAC;IAEF,iBAAiB;IACjB,UAAU,CAAC,QAAQ,GAAG,KAAK,CAAC;AAChC,CAAC;AAED,KAAK,UACL,SAAS,CACJ,OAAgC,EAChC,OAAgC,EAChC,OAAgC,EAChC,OAAgC,EAChC,aAAmC,EACnC,aAAgC;IAGjC,kBAAkB;IAClB,IAAI,UAAU,GAAY,OAAO,CAAC,KAAK,CAAC;IACxC,IAAI,SAAS,GAAa,OAAO,CAAC,KAAK,CAAC;IACxC,IAAI,MAAM,GAAgB,QAAQ,CAAC,OAAO,CAAC,KAAK,CAAC,CAAC;IAClD,IAAI,OAAO,GAAe,OAAO,CAAC,KAAK,CAAC;IAExC,IAAI,MAAM,GAAsB,MAAM,aAAa,CAAC,UAAU,EAAE,SAAS,EAAE,MAAM,EAAE,OAAO,CAAC,CAAC;IAE5F,yBAAyB;IACzB,IAAI,MAAM,CAAC,EAAE,EAAE,CAAC;QACZ,IAAI,GAAG,GAAmB,MAAM,CAAC,MAAM,CAAC,GAAG,CAAC;QAC5C,IAAI,UAAU,GAAY,MAAM,CAAC,MAAM,CAAC,UAAU,CAAC;QAEnD,IAAI,UAAU,GAAY,wBAAwB,CAAA;QAElD,IAAI,GAAG,GAAG,UAAU,GAAG,UAAU,CAAC;QAElC,aAAa,CAAC,SAAS,GAAG,GAAG,CAAC;QAC9B,aAAa,CAAC,GAAG,GAAS,GAAG,CAAC;QAE9B,aAAa,CAAC,MAAM,GAAG,KAAK,CAAC;QAC7B,aAAa,CAAC,MAAM,GAAG,KAAK,CAAC;IACjC,CAAC;SACI,CAAC;QACF,KAAK,CAAC,SAAS,GAAG,MAAM,CAAC,KAAK,CAAC,CAAC;IACpC,CAAC;AACL,CAAC;AASD;;GAEG;AACH,KAAK,UACL,aAAa,CACR,MAAkB,EAClB,SAAkB,EAClB,MAAkB,EAClB,OAAkB;IAGnB,kCAAkC;IAClC,IAAI,GAAG,GAAiB,EAAC,YAAY,EAAG,MAAM;QACrB,WAAW,EAAI,SAAS;QACxB,QAAQ,EAAO,MAAM;QACrB,SAAS,EAAM,OAAO,EAAC,CAAC;IACjD,IAAI,QAAQ,GAAY,IAAI,CAAC,SAAS,CAAC,GAAG,EAAE,SAAS,EAAE,CAAC,CAAC,CAAC;IAG1D,IAAI,GAAG,GAAG,aAAa,CAAC;IACxB,IAAI,WAAW,GAAI,EAAC,MAAM,EAAG,MAAM;QACf,OAAO,EAAE,EAAC,cAAc,EAAE,kBAAkB,EAAC;QAC7C,IAAI,EAAK,QAAQ,EAAC,CAAC;IAGvC,IAAI,MAAM,GACF,EAAC,EAAE,EAAM,KAAK;QACb,KAAK,EAAG,kCAAkC,EAAC,CAAC;IAErD,IAAI,CAAC;QACD,IAAI,QAAQ,GAAc,MAAM,KAAK,CAAC,GAAG,EAAE,WAAW,CAAC,CAAC;QACxD,IAAI,QAAQ,CAAC,EAAE;YACX,MAAM,GAAG,MAAM,QAAQ,CAAC,IAAI,EAAuB,CAAC;aACnD,CAAC;YACF,OAAO,CAAC,GAAG,CAAC,oBAAoB,EAAE,QAAQ,CAAC,CAAC;YAC5C,MAAM,GAAG,EAAC,EAAE,EAAE,KAAK,EAAE,KAAK,EAAE,mBAAmB,EAAC,CAAC;QACrD,CAAC;IACL,CAAC;IACD,OAAO,CAAM,EAAE,CAAC;QACZ,OAAO,CAAC,GAAG,CAAC,gBAAgB,EAAE,CAAC,CAAC,CAAC;QACjC,MAAM,GAAG,EAAC,EAAE,EAAE,KAAK,EAAE,KAAK,EAAE,eAAe,EAAC,CAAC;IACjD,CAAC;IAED,OAAO,MAAM,CAAC;AAClB,CAAC"}
@@ -0,0 +1,136 @@
+/**
+ * Title:           GRIDS Basic Page Script
+ * Description:     Page Script for /grids-basic.html
+ * Author:          Peter Harpending <peterharpending@qpq.swiss>
+ * Date:            2025-12-29
+ * Last-Updated:    2025-12-29
+ *
+ * @module
+ */
+
+main();
+
+
+/**
+ * Runs on page load
+ */
+async function
+main
+    ()
+{
+    let n_input    = document.getElementById('grids-n')      as HTMLInputElement;
+    let r_input    = document.getElementById('grids-r')      as HTMLInputElement;
+    let a_input    = document.getElementById('grids-a')      as HTMLInputElement;
+    let p_input    = document.getElementById('grids-p')      as HTMLInputElement;
+    let submit_btn = document.getElementById('grids-submit') as HTMLInputElement;
+
+    let grids_url_elt = document.getElementById('grids-url') as HTMLTextAreaElement;
+    let grids_png_elt = document.getElementById('grids-png') as HTMLImageElement;
+
+    let rand_data : Uint8Array = new Uint8Array(32);
+    window.crypto.getRandomValues(rand_data);
+    let hex : string = rand_data.toHex().toUpperCase();
+    p_input.value = 'text payload ' + hex;
+
+    // Page initialization
+    submit_btn.addEventListener(
+        'click',
+        async function(e) {
+            await on_submit(n_input, r_input, a_input, p_input, grids_url_elt, grids_png_elt)
+        }
+    );
+
+    // enable buttons
+    submit_btn.disabled = false;
+}
+
+async function
+on_submit
+    (n_input       : HTMLInputElement,
+     r_input       : HTMLInputElement,
+     a_input       : HTMLInputElement,
+     p_input       : HTMLInputElement,
+     grids_url_elt : HTMLTextAreaElement,
+     grids_png_elt : HTMLImageElement)
+    : Promise<void>
+{
+    // pull out values
+    let network_id : string = n_input.value;
+    let recipient  : string = r_input.value;
+    let amount     : number = parseInt(a_input.value);
+    let payload    : string = p_input.value;
+
+    let result: Safe<GridsResult> = await grids_request(network_id, recipient, amount, payload);
+
+    // show url field and png
+    if (result.ok) {
+        let url        : string = result.result.url;
+        let png_base64 : string = result.result.png_base64;
+
+        let src_prefix : string = 'data:image/png;base64,'
+
+        let src = src_prefix + png_base64;
+
+        grids_url_elt.innerText = url;
+        grids_png_elt.src       = src;
+
+        grids_url_elt.hidden = false;
+        grids_png_elt.hidden = false;
+    }
+    else {
+        alert('ERROR: ' + result.error);
+    }
+}
+
+
+type Safe<t> = {ok: true,  result: t}
+             | {ok: false, error: string};
+
+type GridsResult = {url       : string,
+                    png_base64: string};
+
+/**
+ * gets the grids url
+ */
+async function
+grids_request
+    (net_id    : string,
+     recipient : string,
+     amount    : number,
+     payload   : string)
+    : Promise<Safe<GridsResult>>
+{
+    // format for network transmission
+    let obj      : object = {'network_id' : net_id,
+                             'recipient'  : recipient,
+                             'amount'     : amount,
+                             'payload'    : payload};
+    let obj_text : string = JSON.stringify(obj, undefined, 4);
+
+
+    let url = '/grids-mkdd';
+    let req_options  = {method:  'POST',
+                        headers: {'content-type': 'application/json'},
+                        body:    obj_text};
+
+
+    let result: Safe<GridsResult> =
+            {ok    : false,
+             error : 'IT DO BE LIKE THAT MISTA STANCIL'};
+
+    try {
+        let response : Response = await fetch(url, req_options);
+        if (response.ok)
+            result = await response.json() as Safe<GridsResult>;
+        else {
+            console.log('bad http response:', response);
+            result = {ok: false, error: 'BAD HTTP RESPONSE'};
+        }
+    }
+    catch (x: any) {
+        console.log('network error:', x);
+        result = {ok: false, error: 'NETWORK ERROR'};
+    }
+
+    return result;
+}
@@ -0,0 +1,150 @@
+% @doc grids cache
+-module(fd_gridsd).
+-vsn("0.2.0").
+
+-behavior(gen_server).
+
+-export_type([
+]).
+
+-export([
+    %% caller context
+    mkdd/4,
+
+    %% api
+    start_link/0,
+
+    %% process context
+    init/1, handle_call/3, handle_cast/2, handle_info/2,
+    code_change/3, terminate/2
+]).
+
+-include("$zx_include/zx_logger.hrl").
+
+-type hex() :: binary().
+-define(SEC, 1).
+-define(MIN, 60*SEC).
+-define(DEAD_DROP_TTL, 30*MIN).
+
+-record(dd,
+        {created_at :: integer(),
+         payload    :: string()}).
+-type dd()  :: #dd{}.
+
+-record(s,
+        {drops = #{} :: #{hex() := dd()}}).
+
+-type state() :: #s{}.
+
+
+%%-----------------------------------------------------------------------------
+%% caller context
+%%-----------------------------------------------------------------------------
+
+-spec mkdd(NetworkId, Recipient, Amount, Payload) -> Result
+    when NetworkId :: string(),
+         Recipient :: string(),
+         Amount    :: non_neg_integer(),
+         Payload   :: binary(),
+         Result    :: {ok, URL, QR_PNG}
+                    | {error, string()},
+         URL       :: string(),
+         QR_PNG    :: binary().
+% @doc
+% make a dead drop
+
+mkdd(NetworkId, Recipient, Amount, Payload) ->
+    gen_server:call(?MODULE, {mkdd, NetworkId, Recipient, Amount, Payload}).
+
+
+%% gen_server callbacks
+start_link() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, none, []).
+
+
+%%-----------------------------------------------------------------------------
+%% process context below this line
+%%-----------------------------------------------------------------------------
+
+%% gen_server callbacks
+
+init(none) ->
+    tell("starting fd_gridsd"),
+    InitState = #s{},
+    {ok, InitState}.
+
+
+handle_call({mkdd, NetworkId, Recipient, Amount, Payload}, From, State) ->
+    case do_mkdd(NetworkId, Recipient, Amount, Payload, State) of
+        {ok, URL, PNG, NewState} -> {reply, {ok, URL, PNG}, NewState};
+        Error                    -> {reply, Error, State}
+    end;
+handle_call(Unexpected, From, State) ->
+    tell("~tp: unexpected call from ~tp: ~tp", [?MODULE, Unexpected, From]),
+    {noreply, State}.
+
+
+handle_cast(Unexpected, State) ->
+    tell("~tp: unexpected cast: ~tp", [?MODULE, Unexpected]),
+    {noreply, State}.
+
+
+handle_info(Unexpected, State) ->
+    tell("~tp: unexpected info: ~tp", [?MODULE, Unexpected]),
+    {noreply, State}.
+
+
+code_change(_, State, _) ->
+    {ok, State}.
+
+terminate(_, _) ->
+    ok.
+
+
+%%-----------------------------------------------------------------------------
+%% internals
+%%-----------------------------------------------------------------------------
+
+-spec do_mkdd(NetworkId, Recipient, Amount, Payload, State) -> Result
+    when NetworkId :: string(),
+         Recipient :: string(),
+         Amount    :: pos_integer(),
+         Payload   :: binary(),
+         State     :: state(),
+         Result    :: {ok, URL, QR_PNG, NewState}
+                    | {error, Reason},
+         URL      :: string(),
+         QR_PNG   :: binary(),
+         NewState :: state(),
+         Reason   :: any().
+
+do_mkdd(NetId, Recipient, Amount, Payload, State = #s{drops = Drops}) ->
+    HexStr    = rand_hex(),
+    CreatedAt = now_sec(),
+    TxStr     = form_txstr(NetId, Recipient, Amount, Payload),
+    DD        = #dd{created_at = CreatedAt, payload = TxStr},
+    URL       = dd_url(HexStr),
+    PNG       = qr:encode_png(unicode:characters_to_binary(URL)),
+    NewDrops  = maps:put(HexStr, DD, Drops),
+    NewState  = State#s{drops = NewDrops},
+    {ok, URL, PNG, NewState}.
+
+now_sec() ->
+    calendar:datetime_to_gregorian_seconds(calendar:universal_time()).
+
+
+-spec rand_hex() -> hex().
+rand_hex() ->
+    unicode:characters_to_binary(hexify(rand:bytes(10))).
+
+hexify(<<B:8, Rest/binary>>) when B < 16#10 -> ["0", integer_to_list(B, 16), hexify(Rest)];
+hexify(<<B:8, Rest/binary>>)                -> [integer_to_list(B, 16), hexify(Rest)];
+hexify(<<>>)                                -> [].
+
+dd_url(HexStr) ->
+    unicode:characters_to_list(["grids://", fewd:host(), "/1/d/", HexStr]).
+
+
+% ref
+form_txstr(_NetId, _Recipient, _Amount, _Payload) ->
+    "foobar".
@@ -238,6 +238,7 @@ route(Sock, get, Route, Request, Received) ->
    end;
 route(Sock, post, Route, Request, Received) ->
    case Route of
+         <<"/grids-mkdd">> -> grids_mkdd(Sock, Request) , Received;
         <<"/wfcin">>      -> wfcin(Sock, Request) , Received;
         _                 -> fd_httpd_utils:http_err(Sock, 404)  , Received
    end;
@@ -319,6 +320,36 @@ ws_echo_loop(Sock, Frames, Received) ->
            error(Error)
    end.

+%% ------------------------------
+%% grids
+%% ------------------------------
+
+grids_mkdd(Sock, #request{enctype = json,
+                          body = B = #{"network_id" := NetId,
+                                       "recipient"  := Recipient,
+                                       "amount"     := Amount,
+                                       "payload"    := Payload}}) ->
+    tell("grids_mkdd good request: ~tp", [B]),
+    RespObj =
+        case fd_gridsd:mkdd(NetId, Recipient, Amount, unicode:characters_to_binary(Payload)) of
+            {ok, URL, PNG} ->
+                #{"ok"         => true,
+                  "result"     => #{"url"        => URL,
+                                    "png_base64" => unicode:characters_to_list(base64:encode(PNG))}};
+            {error, String} ->
+                #{"ok"    => false,
+                  "error" => String}
+        end,
+    Body = zj:encode(RespObj),
+    % update cache with new context
+    Response = #response{headers = [{"content-type", "application/json"}],
+                         body    = Body},
+    fd_httpd_utils:respond(Sock, Response);
+grids_mkdd(Sock, Request) ->
+    tell("grids_mkdd: bad request: ~tp", [Request]),
+    fd_httpd_utils:http_err(Sock, 400).
+
+

 %% ------------------------------
 %% wfc
@@ -0,0 +1,84 @@
+% @doc hz helper functions
+-module(fd_hz).
+
+-export_type([
+]).
+
+-export([
+    txs_current/0,
+    txs_since_height/1,
+    txs_minus/1,
+    txs_from_to/2,
+    current_height/0,
+    txs_of_height/1,
+    mhs_of_height/1,
+    txs_of_mh/1,
+    filter_spends/1,
+    filter_spend/1,
+    spend_info/1,
+    test/0
+]).
+
+
+-spec test() -> no_return().
+
+test() ->
+    io:format("~tp~n", [hz:gen_current()]),
+    io:format("~tp~n", [hz:kb_current()]),
+    ok.
+
+
+
+txs_current() ->
+    H = current_height(),
+    txs_of_height(H).
+
+
+txs_since_height(H) ->
+    txs_from_to(H, current_height()).
+
+
+txs_minus(N) ->
+    H = current_height(),
+    L = H - N,
+    txs_from_to(L, H).
+
+
+txs_from_to(Min, Max) when Min =< Max ->
+    lists:append([txs_of_height(H) || H <- lists:seq(Min, Max)]);
+txs_from_to(Min, Max) when Min > Max ->
+    [].
+
+
+current_height() ->
+    {ok, H} = hz:kb_current_height(),
+    H.
+
+
+txs_of_height(Height) ->
+    lists:append([txs_of_mh(MH) || MH <- mhs_of_height(Height)]).
+
+
+-spec mhs_of_height(Height :: pos_integer()) -> term().
+mhs_of_height(Height) ->
+    {ok, #{"micro_blocks" := MHs}} = hz:gen_by_height(Height),
+    MHs.
+
+
+txs_of_mh(MH) ->
+    {ok, TXs} = hz:mb_txs(MH),
+    TXs.
+
+
+filter_spends(TXs) ->
+    lists:filtermap(fun filter_spend/1, TXs).
+
+filter_spend(#{"tx" := TX = #{"type" := "SpendTx"}}) -> {true, spend_info(TX)};
+filter_spend(_)                                      -> false.
+
+
+spend_info(#{"type" := "SpendTx",
+             "recipient_id" := Recipient,
+             "amount" := Amount,
+             "payload" := Payload}) ->
+    {sp, Recipient, Amount, Payload}.
@@ -0,0 +1,213 @@
+% @doc spy: knows constraints {recipient, amount, payload}
+%
+% spies the chain for transactions that satisfy that constraint
+%
+-module(fd_spy).
+-vsn("0.2.0").
+
+% MVP: register search patterns
+% simply print to console when one of them is found
+
+-behavior(gen_server).
+
+-export_type([
+]).
+
+-export([
+    %% caller context
+    reg/3,
+
+    %% api
+    start_link/0,
+
+    %% process context
+    init/1, handle_call/3, handle_cast/2, handle_info/2,
+    code_change/3, terminate/2
+]).
+
+% recipient is a string
+-type pubkey32() :: <<_:256>>.
+
+-record(sp,
+        {recipient  :: pubkey32(),
+         amount     :: pos_integer(),
+         payload    :: binary()}).
+-type search_pattern() :: #sp{}.
+
+-record(s,
+        {last_height_seen = none :: none | integer(),
+         searching_for    = []   :: [search_pattern()]}).
+
+-type state() :: #s{}.
+
+-include("$zx_include/zx_logger.hrl").
+
+%%-----------------------------------------------------------------------------
+%% caller context
+%%-----------------------------------------------------------------------------
+
+-spec reg(Recipient, Amount, Payload) -> ok | {error, Reason}
+    when Recipient :: pubkey32(),
+         Amount    :: pos_integer(),
+         Payload   :: binary(),
+         Reason    :: any().
+
+reg(R, A, P) when is_binary(R), byte_size(R) =:= 32,
+                  is_integer(A), A >= 0,
+                  is_binary(P) ->
+    gen_server:call(?MODULE, {reg, R, A, P}).
+
+
+
+%% gen_server callbacks
+start_link() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, none, []).
+
+
+%%-----------------------------------------------------------------------------
+%% process context below this line
+%%-----------------------------------------------------------------------------
+
+%% gen_server callbacks
+
+-spec init(none) -> {ok, state()}.
+
+init(none) ->
+    tell("starting fd_spy"),
+    hz:chain_nodes(fewd:chain_nodes()),
+    erlang:send_after(1000, self(), check_chain),
+    InitState = #s{},
+    {ok, InitState}.
+
+
+
+-spec handle_call(Msg, From, State) -> Result
+    when Msg      :: any(),
+         From     :: {pid(), reference()},
+         State    :: state(),
+         Result   :: {reply, Reply, NewState}
+                   | {noreply, NewState},
+         Reply    :: any(),
+         NewState :: state().
+
+handle_call({reg, Recipient, Amount, Payload}, _From, State) ->
+    {Reply, NewState} = do_reg(Recipient, Amount, Payload, State),
+    {reply, Reply, NewState};
+handle_call(Unexpected, From, State) ->
+    tell("~tp: unexpected call from ~tp: ~tp", [?MODULE, Unexpected, From]),
+    {noreply, State}.
+
+
+
+handle_cast(Unexpected, State) ->
+    tell("~tp: unexpected cast: ~tp", [?MODULE, Unexpected]),
+    {noreply, State}.
+
+
+
+handle_info(check_chain, State) ->
+    NewState = do_check_chain(State),
+    erlang:send_after(1000, self(), check_chain),
+    {noreply, NewState};
+handle_info(Unexpected, State) ->
+    tell("~tp: unexpected info: ~tp", [?MODULE, Unexpected]),
+    {noreply, State}.
+
+
+
+code_change(_, State, _) ->
+    {ok, State}.
+
+
+
+terminate(_, _) ->
+    ok.
+
+
+
+%%-----------------------------------------------------------------------------
+%% internals
+%%-----------------------------------------------------------------------------
+
+do_check_chain(State = #s{last_height_seen = none}) ->
+    case hz:kb_current_height() of
+        {ok, Max} ->
+            hh(Max-1, Max, State);
+        Error     ->
+            tell("~tp hz error: ~tp", [?MODULE, Error]),
+            State
+    end;
+do_check_chain(State = #s{last_height_seen = Min}) ->
+    case hz:kb_current_height() of
+        {ok, Max} ->
+            hh(Min, Max, State);
+        Error     ->
+            tell("~tp hz error: ~tp", [?MODULE, Error]),
+            State
+    end.
+
+% handle height
+hh(PrevHeight, NewHeight, State) when PrevHeight < NewHeight ->
+    tell("~tp cool: PrevHeight=~tp, NewHeight=~tp", [?MODULE, PrevHeight, NewHeight]),
+    Spends = fd_hz:filter_spends(fd_hz:txs_from_to(PrevHeight + 1, NewHeight)),
+    tell("~tp spends: ~tp", [?MODULE, Spends]),
+    NewState = State#s{last_height_seen = NewHeight},
+    NewState;
+hh(PrevHeight, NewHeight, State) when PrevHeight >= NewHeight ->
+    log(info, "~tp lame: PrevHeight=~tp, NewHeight=~tp", [?MODULE, PrevHeight, NewHeight]),
+    State.
+
+
+-spec do_reg(Recipient, Amount, Payload, State) -> {Reply, NewState}
+    when Recipient :: pubkey32(),
+         Amount    :: pos_integer(),
+         Payload   :: binary(),
+         State     :: state(),
+         Reply     :: ok
+                    | {error, Reason},
+         Reason    :: any(),
+         NewState  :: state().
+
+do_reg(Recipient, Amount, Payload, State) ->
+    case already_registered(Recipient, Payload, State) of
+        true  -> {error, already_registered};
+        false -> really_register(Recipient, Amount, Payload, State)
+    end.
+
+
+
+-spec already_registered(Recipient, Payload, State) -> boolean()
+    when Recipient :: pubkey32(),
+         Payload   :: binary(),
+         State     :: state().
+
+already_registered(Recipient, Payload, _State = #s{searching_for = SPs}) ->
+    ar(Recipient, Payload, SPs).
+
+ar(Recipient, Payload, [#sp{recipient=Recipient, payload=Payload} | _]) ->
+    true;
+ar(Recipient, Payload, [_ | Rest]) ->
+    ar(Recipient, Payload, Rest);
+ar(_, _, []) ->
+    false.
+
+
+
+-spec really_register(Recipient, Amount, Payload, State) -> {Reply, NewState}
+    when Recipient :: pubkey32(),
+         Amount    :: pos_integer(),
+         Payload   :: binary(),
+         State     :: state(),
+         Reply     :: ok
+                    | {error, Reason},
+         Reason    :: any(),
+         NewState  :: state().
+
+really_register(R, A, P, State = #s{searching_for = SPs}) ->
+    NewSearchPattern = #sp{recipient = R,
+                           amount    = A,
+                           payload   = P},
+    tell("~tp: really_register(~tp,~tp,~tp)", [?MODULE, R, A, P]),
+    NewSearchPatterns = [NewSearchPattern | SPs],
+    NewState = State#s{searching_for = NewSearchPatterns},
+    {reply, ok, NewState}.
@@ -36,6 +36,18 @@ start_link() ->

 init([]) ->
    RestartStrategy = {one_for_one, 1, 60},
+    Spy       = {fd_spy,
+                 {fd_spy, start_link, []},
+                 permanent,
+                 5000,
+                 worker,
+                 [fd_spy]},
+    GridsD    = {fd_gridsd,
+                 {fd_gridsd, start_link, []},
+                 permanent,
+                 5000,
+                 worker,
+                 [fd_gridsd]},
    WFCd      = {fd_wfcd,
                 {fd_wfcd, start_link, []},
                 permanent,
@@ -48,5 +60,5 @@ init([]) ->
                 5000,
                 supervisor,
                 [fd_httpd]},
-    Children  = [WFCd, Httpd],
+    Children  = [Spy, GridsD, WFCd, Httpd],
    {ok, {RestartStrategy, Children}}.
@@ -9,12 +9,34 @@
 -copyright("Peter Harpending <peterharpending@qpq.swiss>").
 -license("BSD-2-Clause-FreeBSD").

+-export([chain_nodes/0, url/0, host/0, network_id/0, pubkey/0, akstr/0]).
 -export([listen/1, ignore/0]).
 -export([start/2, stop/1]).

 -include("$zx_include/zx_logger.hrl").


+%% for testing: use mainnet
+%chain_nodes() ->
+%    [{"tsuriai.jp", 3013}].
+chain_nodes() ->
+    [{"tsuriai.jp", 4013}].
+
+url()        -> "http://" ++ host().
+host()       -> "localhost:8000".
+network_id() -> "groot.testnet".
+pubkey()     -> pad32(<<"fewd demo">>).
+akstr()      -> gmgrids:akstr(pubkey()).
+
+
+pad32(Bytes) ->
+    BS = byte_size(Bytes),
+    Spaces = << <<" ">>
+             || _ <- lists:seq(BS, 31)
+             >>,
+    <<Bytes/bytes, Spaces/bytes>>.
+
+
 -spec listen(PortNum) -> Result
    when PortNum :: inet:port_num(),
         Result  :: ok
@@ -42,6 +64,7 @@ ignore() ->
 %% See: http://erlang.org/doc/apps/kernel/application.html

 start(normal, _Args) ->
+    ok = application:ensure_started(hakuzaru),
    Result = fd_sup:start_link(),
    ok = listen(8000),
    Result.
@@ -0,0 +1,618 @@
+% @doc
+% GRIDS library: grids
+%
+% This module simply handles encoding and decoding of GRIDS URLs.
+%
+% For documentation on GRIDS see
+%
+%    https://git.qpq.swiss/QPQ-AG/research-megadoc/wiki/GRIDS
+% @end
+-module(gmgrids).
+-vsn("0.2.0").
+-author("Peter Harpending <peterharpending@qpq.swiss>").
+-copyright("2025 QPQ AG").
+-license("MIT").
+
+% TODONE:
+%
+% TODO:
+%
+% - possibly input types should be iolists. I think for
+%   binaries it's fine
+% - change the types... don't need 3 different record types
+
+
+% FIXEDME:
+%
+% FIXME:
+
+-export_type([
+    % field types
+    host/0,
+    target/0, akstr/0, pubkey/0,
+
+    % record types
+    grids/0
+]).
+
+-export([
+    % convenience functions
+    %% currency granularities
+    p/0, kp/0, mp/0, gp/0, tp/0, pp/0,
+    g/0, kg/0, mg/0, gg/0, tg/0,
+    %% type fuckery
+    target_to_path/1, akstr/1, unakstr/1,
+    dummy_target/0,
+    %% convenience encoders
+    encode/2,
+
+    % "primitives"
+    %% record constructor
+    mk_grids/2,
+    %% primitive encoders
+    encode/1, encode/7, percent_encode/1,
+    %% decoder
+    decode/1
+]).
+
+
+%%-------------------------------------------------------------------
+%% API: TYPES
+%%-------------------------------------------------------------------
+
+% @doc Future-proofing... later this could be inet:addr() or whatever, or maybe
+% {Host, Port}. Keeping it simple for now
+-type host() :: string().
+
+% @doc ak_... string
+-type akstr() :: string().
+
+% @doc 32-byte public key
+-type pubkey() :: <<_:256>>.
+
+% @doc later might want this to be flexible, "ak_..." etc
+%
+% FIXME: add support for all the different api keys: ak_..., ct_..., etc
+-type target() :: pubkey()
+                | akstr().
+
+-record(grids,
+        {secure      = true :: boolean(),
+         host               :: host(),
+         version     =   1  :: integer(),
+         instruction        :: dead_drop | spend | transfer,
+         path               :: string(),
+         amount      = none :: none | {value, integer()},
+         payload     = none :: none | {value, binary()}}).
+
+-type grids() :: #grids{}.
+
+
+%%-------------------------------------------------------------------
+%% API: CONVENIENCE FUNCTIONS
+%%-------------------------------------------------------------------
+
+%% currency granularities
+p()  -> 1.
+kp() -> 1_000.
+mp() -> 1_000_000.
+gp() -> 1_000_000_000.
+tp() -> 1_000_000_000_000.
+pp() -> 1_000_000_000_000_000.
+g()  -> 1_000_000_000_000_000_000.
+kg() -> 1_000_000_000_000_000_000_000.
+mg() -> 1_000_000_000_000_000_000_000_000.
+gg() -> 1_000_000_000_000_000_000_000_000_000.
+tg() -> 1_000_000_000_000_000_000_000_000_000_000.
+
+
+-spec target_to_path(Target) -> Path
+    when Target :: target(),
+         Path   :: string().
+% @doc
+% Internal function exported for convenience purposes
+%
+% If `Target' is an "ak_..." string, leave as-is. If it's a 32 byte public key
+% encode as an ak_... string
+
+target_to_path(Target) ->
+    i_ttp(iolist_to_binary(Target)).
+
+i_ttp(ApiStr = <<"ak_", _/binary>>) -> ApiStr;
+i_ttp(Pubkey = <<_:32/bytes>>)      -> akstr(Pubkey);
+i_ttp(BadTarget)                    -> error({invalid_target, BadTarget}).
+
+
+%% akstr/unakstr
+-spec akstr(Pubkey) -> AkStr
+    when Pubkey :: pubkey(),
+         AkStr  :: akstr().
+% @doc
+% convert a 32-byte public key into an ak_... string
+
+akstr(PK) ->
+    unicode:characters_to_list(gmser_api_encoder:encode(account_pubkey, PK)).
+
+
+
+-spec unakstr(AkStr) -> Pubkey
+    when Pubkey :: pubkey(),
+         AkStr  :: string().
+% @doc
+% convert an ak_... string into a 32-byte public key
+
+unakstr(Akstr) ->
+    {_, PK} = gmser_api_encoder:decode(unicode:characters_to_binary(Akstr)),
+    PK.
+
+
+
+-spec dummy_target() -> akstr().
+% @doc Make a dummy public key. For testing purposes. NOT secure!
+
+dummy_target() ->
+    akstr(rand:bytes(32)).
+
+
+-spec encode(Args, Options) -> URL
+    when Args      :: {dead_drop, Host, Path}
+                    | {spend, NetworkId, Recipient}
+                    | {transfer, Host, Path},
+         Host      :: iolist(),
+         Path      :: iolist(),
+         NetworkId :: iolist(),
+         Recipient :: target(),
+         Options   :: [Opt],
+         Opt       :: {secure, boolean()}
+                    | {version, integer()}
+                    | {amount, Amount}
+                    | {payload, Payload},
+         Amount     :: integer() | none | {value, integer()},
+         Payload    :: iolist()  | none | {value, iolist()},
+         URL        :: string().
+
+encode(Args, Opts) ->
+    encode(mk_grids(Args, Opts)).
+
+
+%%-------------------------------------------------------------------
+%% API: RECORD CONSTRUCTORS
+%%-------------------------------------------------------------------
+
+-record(o,
+        {secure  = true :: boolean(),
+         version =   1  :: integer(),
+         amount  = none :: none | {value, integer()},
+         payload = none :: none | {value, binary()}}).
+
+-spec mk_grids(Args, Options) -> Grids
+    when Args      :: {dead_drop, Host, Path}
+                    | {spend, NetworkId, Recipient}
+                    | {transfer, Host, Path},
+         Host      :: iolist(),
+         Path      :: iolist(),
+         NetworkId :: iolist(),
+         Recipient :: target(),
+         Options   :: [Opt],
+         Opt       :: {secure, boolean()}
+                    | {version, integer()}
+                    | {amount, Amount}
+                    | {payload, Payload},
+         Amount     :: integer() | none | {value, integer()},
+         Payload    :: iolist()  | none | {value, iolist()},
+         Grids      :: #grids{}.
+
+mk_grids(Args, Options) ->
+    #o{secure  = Secure,
+       version = Version,
+       amount  = MaybeAmount,
+       payload = MaybePayload} = i_valid_opts(Options),
+    {Instruction, HostStr, Path} =
+        case Args of
+            {dead_drop, H0, P0} ->
+                H1 = unicode:characters_to_list(H0),
+                P1 = unicode:characters_to_list(P0),
+                {dead_drop, H1, P1};
+            {spend, NetId0, Recip0} ->
+                NetId1 = unicode:characters_to_list(NetId0),
+                Recip1 = target_to_path(Recip0),
+                {spend, NetId1, Recip1};
+            {transfer, H0, P0} ->
+                H1 = unicode:characters_to_list(H0),
+                P1 = unicode:characters_to_list(P0),
+                {transfer, H1, P1}
+        end,
+    #grids{secure      = Secure,
+           host        = HostStr,
+           version     = Version,
+           instruction = Instruction,
+           path        = Path,
+           amount      = MaybeAmount,
+           payload     = MaybePayload}.
+
+
+i_valid_opts(Options) ->
+    Secure =
+        case proplists:get_value(secure, Options, true) of
+            S when is_boolean(S) -> S;
+            W                    -> error({invalid_option, {secure, W}})
+        end,
+    Version =
+        case proplists:get_value(version, Options, 1) of
+            V when is_integer(V) -> V;
+            X                    -> error({invalid_option, {version, X}})
+        end,
+    Amount =
+        case proplists:get_value(amount, Options, none) of
+            none                          -> none;
+            {value, N} when is_integer(N) -> {value, N};
+            N          when is_integer(N) -> {value, N};
+            Y                             -> error({invalid_option, {amount, Y}})
+        end,
+    Payload =
+        case proplists:get_value(payload, Options, none) of
+            none       -> none;
+            {value, P} -> {value, iolist_to_binary(P)};
+            P          -> {value, iolist_to_binary(P)}
+        end,
+    #o{secure     = Secure,
+       version    = Version,
+       amount     = Amount,
+       payload    = Payload}.
+
+
+
+
+%%-------------------------------------------------------------------
+%% API: ENCODING (Record -> URL)
+%%-------------------------------------------------------------------
+
+-spec encode(GRIDS) -> URL
+    when GRIDS :: grids(),
+         URL   :: string().
+% @doc
+% Encode a grids record type
+% @end
+
+encode(#grids{secure      = Secure,
+              host        = Host,
+              version     = Vsn,
+              instruction = Instruction,
+              path        = Path,
+              amount      = Amt,
+              payload     = Payload}) ->
+    encode(Secure, Host, Vsn, Instruction, Path, Amt, Payload).
+
+
+-spec encode(Secure, Host, Version, Instruction, Path, Amount, Payload) -> URL
+    when Secure      :: boolean(),
+         Host        :: host(),
+         Version     :: integer(),
+         Instruction :: dead_drop | spend | transfer,
+         Path        :: string(),
+         Amount      :: none | {value, integer()},
+         Payload     :: none | {value, binary()},
+         URL         :: string().
+% @doc
+% internal encode that's more verbose
+
+encode(Secure, Host, Version, Instruction, Path, Amount, Payload) ->
+    unicode:characters_to_list(
+        ["grid", i_encode_secure(Secure),
+         "://", i_encode_host(Host),
+         "/", integer_to_list(Version),
+         "/", i_encode_instruction(Instruction),
+         "/", Path,
+         i_encode_qstr(Amount, Payload)]
+    ).
+
+i_encode_secure(true)  -> "s";
+i_encode_secure(false) -> "".
+
+% future-proofing against more complicated host arguments
+i_encode_host(Host) -> Host.
+
+i_encode_instruction(dead_drop) -> "d";
+i_encode_instruction(spend)     -> "s";
+i_encode_instruction(transfer)  -> "t".
+
+i_encode_qstr(none, none) ->
+    "";
+i_encode_qstr({value, Amt}, none) ->
+    ["?a=", integer_to_list(Amt)];
+i_encode_qstr(none, {value, Payload}) ->
+    ["?p=", percent_encode(Payload)];
+i_encode_qstr({value, Amt}, {value, Payload}) ->
+    ["?a=", integer_to_list(Amt),
+     "&p=", percent_encode(Payload)].
+
+
+-spec percent_encode(Payload) -> PercentEncoded
+    when Payload        :: binary(),
+         PercentEncoded :: iolist().
+% @doc
+% internal function to percent-encode binary payload
+% exported for convenience
+%
+% See: https://en.wikipedia.org/wiki/Percent-encoding
+
+percent_encode(Payload) when is_binary(Payload) ->
+    i_percent_encode(Payload, []).
+
+% unreserved characters
+i_percent_encode(<<C:8, Rest/binary>>, Acc)
+        when ($A =< C andalso C =< $Z) orelse
+             ($a =< C andalso C =< $z) orelse
+             ($0 =< C andalso C =< $9) orelse
+             (C =:= $-) orelse
+             (C =:= $_) orelse
+             (C =:= $~) orelse
+             (C =:= $.) ->
+    i_percent_encode(Rest, [Acc, C]);
+i_percent_encode(<<B:8, Rest/binary>>, Acc) ->
+    i_percent_encode(Rest, [Acc, i_pe_byte(B)]);
+i_percent_encode(<<>>, Result) ->
+    Result.
+
+% single hex digit
+i_pe_byte(B) when 16#00 =< B, B =< 16#0F -> ["%0", integer_to_list(B, 16)];
+i_pe_byte(B) when 16#10 =< B, B =< 16#FF -> ["%", integer_to_list(B, 16)].
+
+
+
+%%---------------------------------------------------------
+%% API: DECODING
+%%---------------------------------------------------------
+
+-record(dt,
+        {secure      = undefined :: undefined | boolean(),
+         host        = undefined :: undefined | iolist(),
+         version     = undefined :: undefined | integer(),
+         instruction = undefined :: undefined | spend | transfer | dead_drop,
+         path        = undefined :: undefined | iolist(),
+         amount      = undefined :: undefined | none | {value, integer()},
+         payload     = undefined :: undefined | none | {value, binary()}}).
+
+% -type decode_target() :: #dt{}.
+
+
+-spec decode(URL) -> Result
+    when URL    :: string(),
+         Result :: {ok, grids(), Remainder :: string()}
+                 | {error, Reason},
+         Reason :: term().
+
+decode(URL) ->
+    case i_decode(unicode:characters_to_binary(URL)) of
+        {ok, DT, Remainder} ->
+            {ok, i_decode_dt(DT), unicode:characters_to_list(Remainder)};
+        Error ->
+            Error
+    end.
+
+i_decode_dt(#dt{secure      = S,
+                host        = H,
+                version     = V,
+                path        = P,
+                instruction = Instruction,
+                amount      = A,
+                payload     = L}) ->
+    HStr = unicode:characters_to_list(H),
+    PStr = unicode:characters_to_list(P),
+    #grids{secure      = S,
+           host        = HStr,
+           version     = V,
+           path        = PStr,
+           instruction = Instruction,
+           amount      = A,
+           payload     = L}.
+
+
+i_decode(URL) ->
+    i_pipeline([fun i_decode_secure/2,
+                fun i_decode_host/2,
+                fun i_decode_version/2,
+                fun i_decode_instruction/2,
+                fun i_decode_path/2,
+                fun i_decode_qstr/2],
+                {ok, #dt{}, URL}).
+
+
+i_pipeline([Fun | Funs], Acc) ->
+    case Acc of
+        {ok, DT, URL} -> i_pipeline(Funs, Fun(DT, URL));
+        Error         -> Error
+    end;
+i_pipeline([], Result) ->
+    Result.
+
+
+i_decode_secure(DT = #dt{secure = undefined},
+                <<"grid://", Rest/binary>>) ->
+    {ok, DT#dt{secure = false}, Rest};
+i_decode_secure(DT = #dt{secure = undefined},
+                <<"grids://", Rest/binary>>) ->
+    {ok, DT#dt{secure = true}, Rest};
+i_decode_secure(_, URL) ->
+    {error, {bad_protocol, URL}}.
+
+
+
+i_decode_host(DT = #dt{host = undefined}, URL) ->
+    case idh2([], URL) of
+        {ok, Host, Rest} -> {ok, DT#dt{host = Host}, Rest};
+        Error            -> Error
+    end.
+
+% eliminate empty hosts and hosts not followed by /
+idh2([],   <<$/:8, _/binary>>)      -> {error, empty_host};
+idh2([],   <<>>)                    -> {error, empty_host};
+idh2(Host, <<>>)                    -> {error, {bad_host, Host}};
+idh2(Host, <<$/:8, Rest/binary>>)   -> {ok, Host, Rest};
+idh2(Acc,  <<Char:8, Rest/binary>>) -> idh2([Acc, Char], Rest).
+
+
+i_decode_version(DT = #dt{version = undefined}, URL) ->
+    case idv2([], URL) of
+        {ok, VStr, Rest} ->
+            Version = list_to_integer(unicode:characters_to_list(VStr)),
+            NewDT = DT#dt{version = Version},
+            {ok, NewDT, Rest};
+        Error ->
+            Error
+    end.
+
+idv2([],   <<$/:8, _/binary>>)    -> {error, empty_host};
+idv2([],   <<>>)                  -> {error, empty_host};
+idv2(Vstr, <<>>)                  -> {error, {bad_version, iolist_to_binary(Vstr)}};
+idv2(Vstr, <<$/:8, Rest/binary>>) -> {ok, Vstr, Rest};
+idv2(Acc,  <<N:8, Rest/binary>>)  ->
+    case ($0 =< N) andalso (N =< $9) of
+        true  -> idv2([Acc, N], Rest);
+        false -> {error, {illegal_version_char, [N]}}
+    end.
+
+i_decode_instruction(DT = #dt{instruction = undefined}, <<"s/", Rest/binary>>) ->
+    {ok, DT#dt{instruction = spend}, Rest};
+i_decode_instruction(DT = #dt{instruction = undefined}, <<"t/", Rest/binary>>) ->
+    {ok, DT#dt{instruction = transfer}, Rest};
+i_decode_instruction(DT = #dt{instruction = undefined}, <<"d/", Rest/binary>>) ->
+    {ok, DT#dt{instruction = dead_drop}, Rest};
+i_decode_instruction(_ = #dt{instruction = undefined}, Bad) ->
+    {error, {illegal_instruction, Bad}}.
+
+
+i_decode_path(DT = #dt{path = undefined}, URL) ->
+    {Path, Rest} = idp([], URL),
+    {ok, DT#dt{path = Path}, Rest}.
+
+% consume until we get to end of string or ?
+idp(Path, <<"?", Rest/binary>>) -> {Path, Rest};
+idp(Path, <<>>)                 -> {Path, <<>>};
+idp(Path, <<C:8, Rest/binary>>) -> idp([Path, C], Rest).
+
+
+i_decode_qstr(DT = #dt{amount = undefined, payload = undefined}, URL) ->
+    case idq([], URL) of
+        {ok, Proplist, Remainder} ->
+            Amount  = proplists:get_value(amount, Proplist, none),
+            Payload = proplists:get_value(payload, Proplist, none),
+            NewDT   = DT#dt{amount = Amount, payload = Payload},
+            {ok, NewDT, Remainder};
+        Error ->
+            Error
+    end.
+
+
+-spec idq(Proplist, URL) -> Result
+    when URL        :: binary(),
+         Result     :: {ok, Proplist, Remainder}
+                     | {error, ParseError},
+         Proplist   :: [Prop],
+         Prop       :: {amount, {value, integer()}}
+                     | {payload, {value, binary()}},
+         ParseError :: any(),
+         Remainder  :: binary().
+
+idq(Params, <<"a=", Rest/binary>>) ->
+    case i_parse_amt(none, Rest) of
+        {ok, Amt, NewRest} ->
+            NewParams = [{amount, {value, Amt}} | Params],
+            idq(NewParams, NewRest);
+        Error ->
+            Error
+    end;
+idq(Params, <<"p=", Rest/binary>>) ->
+    case i_parse_payload(none, Rest) of
+        {ok, Payload, NewRest} ->
+            NewParams = [{payload, {value, Payload}} | Params],
+            idq(NewParams, NewRest);
+        Error ->
+            Error
+    end;
+idq(Params, Rest) ->
+    {ok, Params, Rest}.
+
+
+-spec i_parse_amt(MaybeAmount, URL) -> Result
+    when URL         :: binary(),
+         Result      :: {ok, MaybeAmount, Rest}
+                      | {error, term()},
+         MaybeAmount :: none | {value, integer()},
+         Rest        :: binary().
+% @private context here is we have an a= and we're parsing what comes after
+% that
+%
+% we can error on empty amounts
+
+i_parse_amt(Acc, <<DigitChar:8, Rest/binary>>)
+        when $0 =< DigitChar, DigitChar =< $9 ->
+    DigitInt = DigitChar - $0,
+    NewAcc =
+        case Acc of
+            none       -> {value, DigitInt};
+            {value, N} -> {value, N*10 + DigitInt}
+        end,
+    i_parse_amt(NewAcc, Rest);
+% either end of string or non-digit char
+i_parse_amt(Acc, <<"&", Rest/binary>>) ->
+    case Acc of
+        {value, Amount} -> {ok, Amount, Rest};
+        none            -> {error, empty_amount}
+    end;
+i_parse_amt(Acc, Rest) ->
+    case Acc of
+        {value, Amount} -> {ok, Amount, Rest};
+        none            -> {error, empty_amount}
+    end.
+
+
+
+-define(IS_HEX_CHAR(P), ((($0 =< P) andalso (P =< $9)) orelse
+                         (($A =< P) andalso (P =< $F)))).
+
+-spec i_parse_payload(MaybePayload, URL) -> Result
+    when URL          :: binary(),
+         Result       :: {ok, MaybePayload, Rest}
+                       | {error, term()},
+         MaybePayload :: none | {value, binary()},
+         Rest         :: binary().
+
+% unreserved chars
+i_parse_payload(Acc, <<C:8, Rest/binary>>)
+        when ($A =< C andalso C =< $Z) orelse
+             ($a =< C andalso C =< $z) orelse
+             ($0 =< C andalso C =< $9) orelse
+             (C =:= $-) orelse
+             (C =:= $_) orelse
+             (C =:= $~) orelse
+             (C =:= $.) ->
+    NewAcc =
+        case Acc of
+            none           -> {value, <<C:8>>};
+            {value, Bytes} -> {value, <<Bytes/bytes, C:8>>}
+        end,
+    i_parse_payload(NewAcc, Rest);
+% percent char
+i_parse_payload(Acc, <<"%", A:8, B:8, Rest/binary>>)
+        when ?IS_HEX_CHAR(A), ?IS_HEX_CHAR(B) ->
+    AInt = list_to_integer([A], 16),
+    BInt = list_to_integer([B], 16),
+    NewByte = AInt*16 + BInt,
+    NewAcc =
+        case Acc of
+            none           -> {value, <<NewByte:8>>};
+            {value, Bytes} -> {value, <<Bytes/binary, NewByte:8>>}
+        end,
+    i_parse_payload(NewAcc, Rest);
+% random char
+i_parse_payload(Acc, <<"&", Rest/binary>>) ->
+    case Acc of
+        none             -> {error, empty_payload};
+        {value, Payload} -> {ok, Payload, Rest}
+    end;
+i_parse_payload(Acc, Rest) ->
+    case Acc of
+        none             -> {error, {illegal_payload, Rest}};
+        {value, Payload} -> {ok, Payload, Rest}
+    end.
@@ -5,7 +5,18 @@
 {prefix,"fd"}.
 {desc,"Front End Web Dev in Erlang stuff"}.
 {package_id,{"otpr","fewd",{0,2,0}}}.
-{deps,[{"otpr","zj",{1,1,2}}]}.
+{deps,[{"otpr","hakuzaru",{0,8,3}},
+            {"otpr","sophia",{9,0,0}},
+            {"otpr","gmserialization",{0,1,3}},
+                {"otpr","eblake2",{1,0,1}},
+                {"otpr","base58",{0,1,1}},
+            {"otpr","gmbytecode",{3,4,1}},
+            {"otpr","base58",{0,1,1}},
+            {"otpr","eblake2",{1,0,1}},
+            {"otpr","ec_utils",{1,0,0}},
+            {"otpr","zj",{1,1,2}},
+            {"otpr","getopt",{1,0,2}},
+       {"otpr","qr",{0,1,0}}]}.
 {key_name,none}.
 {a_email,"peterharpending@qpq.swiss"}.
 {c_email,"peterharpending@qpq.swiss"}.
Author	SHA1	Message	Date
Peter Harpending	46345da283	we now spy keyblocks for spends, need to test but probably close to working	2026-03-02 18:54:33 -08:00
Peter Harpending	bc870e5f2d	wip	2026-03-02 18:27:05 -08:00
Peter Harpending	4ee1825b43	grids random payload defined ok so next step is go on the server side - extract recipient, amount, payload, - register search pattern - wait for matching transaction to appear - notify correct party	2026-02-27 11:43:33 -08:00
Peter Harpending	be6aceb41a	start spy process	2026-02-27 11:34:33 -08:00
pharpend	8a9f060b2d	made a little progress on grids demo i mostly have my head wrapped around the problem a lot more, and need to just let my brain sit	2026-02-25 18:22:26 -08:00
pharpend	9adbf67ebd	shed biketh	2025-12-30 11:45:25 -08:00
pharpend	ee35e6cf1f	HTML BIKESHED	2025-12-29 15:41:29 -08:00
pharpend	3343dcf137	basic grids demo seems to work...	2025-12-29 14:04:03 -08:00
pharpend	f0d1097f1f	qr demo	2025-12-29 08:49:42 -08:00
pharpend	60803b4a4e	start grids qr demo	2025-12-19 17:47:31 -08:00
pharpend	139f9cb9e4	add qr as a dep	2025-12-17 17:34:08 -08:00
				`@@ -0,0 +1 @@`
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