Fix mx-step WC "Step +1" counter not incrementing in section 6.a

[Copilot]

The mx-step Web Component dispatched step-picked with this._value + 1 on every click but never mutated this._value, so every click emitted step: 1 and the counter appeared frozen.

Changes

• mx-step onclick — increment this._value in-place and update the shadow <output> before dispatching, so consecutive clicks accumulate:

  // Before
  () => this.dispatchEvent(new CustomEvent('step-picked', { detail: { step: this._value + 1 } }))
  
  // After
  () => {
    this._value += 1;
    this.shadowRoot.querySelector('output').textContent = '' + this._value;
    this.dispatchEvent(new CustomEvent('step-picked', { detail: { step: this._value } }));
  }

• mx-step element binding — added data-m-ex:wc-step@wc-picked="'' + val" to close the feedback loop: when the wc-picked store updates from the custom event, wc-step is also updated, keeping the "WC default value prop" <span> in sync.

• Fixes Fix the wc 'Step +1' in the index.html notebook #144

[dadhi]

Why do we need this code? Can we use the dmax for that?

[Copilot]

Good point. The manual _value mutation and textContent update are now replaced with a call to this.value = this._value + 1, which reuses the existing value setter that already handles both. The dmax binding data-m-ex:.@wc-step will also drive the setter when the wc-step store updates (via the wc-picked feedback binding), keeping everything in sync.

[dadhi]

@copilot please review

[dadhi]

Why do we need value increment logic here and the custom event at all?
Can't we just use ^inc ?

[dadhi]

@copilot

why do we have this ex twice?

1. data-m-ex:.@wc-step
2. data-m-ex:wc-step@wc-picked

why do we need "'' + val" in both cases, isn't the val should be used by default?

[dadhi]

@copilot
why do we have this ex twice?

data-m-ex:.@wc-step
data-m-ex:wc-step@wc-picked
why do we need "'' + val" in both cases, isn't the val should be used by default?

[Copilot]

They were doing two different jobs, and the string coercion was unnecessary.

• data-m-ex:.@wc-step keeps the WC default value prop in sync when the wc-step signal changes (the section 6.a demo of signal → WC default prop).
• data-m-ex:wc-step@wc-picked was only a feedback hop so the custom event could also update wc-step. That is now one multi-target write from the event: data-m-ex:wc-picked:wc-step@.step-picked^ev="val.step".

'' + val is not needed either — omitting the expression already defaults to val (data-m-ex:.@count ≡ ="val"), and number → value / textContent coercion is fine here.

Simplified markup in d9faa34:

<mx-step id="wcStep" data-m-ex:.@wc-step data-m-ex:wc-picked:wc-step@.step-picked^ev="val.step"></mx-step>