Add popup help to elements

crates/synth-core/src/audio_out.rs

@@ -25,6 +25,16 @@ impl AudioOut {
         params: &[
             ParamDescriptor { id: "level", label: "Level", min: 0.0, max: 1.0, default: 0.8, unit: "", labels: &[] },
         ],
+        description: "\
+## Output — Audio Sink
+
+The final destination in the signal chain, representing the speakers or DAC.
+
+Connect the last audio module's output jack to **In**. The green **● LIVE** badge lights up when a cable is connected and audio is flowing.
+
+**Level** controls the master output volume.
+
+> The oscilloscope and spectrum analyser always reflect what arrives at this node.",
     };
 }
 

crates/synth-core/src/descriptor.rs

@@ -71,4 +71,6 @@ pub struct ComponentDescriptor {
     pub jacks: &'static [JackDescriptor],
     /// Ordered list of tunable parameters.
     pub params: &'static [ParamDescriptor],
+    /// Markdown-formatted help text shown in the patch-bay tooltip.
+    pub description: &'static str,
 }

crates/synth-core/src/envelope.rs

@@ -39,6 +39,19 @@ impl Adsr {
             ParamDescriptor { id: "sustain",   label: "Sustain", min: 0.0,   max: 1.0, default: 0.7,  unit: "",  labels: &[] },
             ParamDescriptor { id: "release_s", label: "Release", min: 0.001, max: 8.0, default: 0.3,  unit: "s", labels: &[] },
         ],
+        description: "\
+## ADSR — Envelope Generator
+
+Produces a CV signal (0–1) that shapes amplitude over time in four stages:
+
+- **Attack** — time to rise from 0 to peak after gate opens
+- **Decay** — time to fall from peak to sustain level
+- **Sustain** — level held while gate remains open
+- **Release** — time to fall back to 0 after gate closes
+
+**This module outputs CV, not audio.** Connect **Env** to a VCA `cv_gain` jack to shape volume, or to `cv_cutoff_hz` on the Filter for a filter envelope.
+
+> **Tip:** VCO Out → VCA In, Keyboard Gate → ADSR Gate, ADSR Env → VCA cv_gain, VCA Out → Output In",
     };
 
     pub fn gate_on(&mut self)  { self.stage = Stage::Attack; }

crates/synth-core/src/filter.rs

@@ -42,6 +42,16 @@ impl Svf {
             ParamDescriptor { id: "cutoff_hz", label: "Cutoff", min: 20.0, max: 20_000.0, default: 2_000.0, unit: "Hz", labels: &[] },
             ParamDescriptor { id: "resonance", label: "Res",    min: 0.0,  max: 1.0,      default: 0.5,     unit: "",   labels: &[] },
         ],
+        description: "\
+## Filter (SVF) — State-Variable Filter
+
+2-pole filter that shapes the tonal colour of an audio signal.
+
+**In** accepts audio; **Out** emits the filtered result.
+
+**Cutoff** sets the corner frequency — frequencies above this point are attenuated (in low-pass mode). **Res** (resonance) narrows the peak; at 1.0 the filter self-oscillates.
+
+Connect an LFO to `cv_cutoff_hz` for a sweeping wah effect, or an ADSR for a filter envelope.",
     };
 
     #[inline]

crates/synth-core/src/lfo.rs

@@ -31,6 +31,18 @@ impl Lfo {
             ParamDescriptor { id: "depth",    label: "Depth", min: 0.0,  max: 1.0,  default: 0.5, unit: "",   labels: &[] },
             ParamDescriptor { id: "waveform", label: "Wave",  min: 0.0,  max: 4.0,  default: 0.0, unit: "",   labels: &["Sine", "Saw", "Sqr", "Tri", "Pls"] },
         ],
+        description: "\
+## LFO — Low-Frequency Oscillator
+
+Like a VCO but running at sub-audio speeds (0.01–20 Hz). Outputs a CV signal (−1 to +1) for modulation.
+
+**Rate** controls oscillation speed. **Depth** scales the output amplitude (0 = no modulation, 1 = full swing).
+
+**Typical uses:**
+
+- LFO Out → VCO `cv_freq_hz` for **vibrato** (pitch wobble)
+- LFO Out → Filter `cv_cutoff_hz` for a **wah/sweep** effect
+- LFO Out → VCA `cv_gain` for **tremolo** (volume wobble)",
     };
 
     #[inline]

crates/synth-core/src/oscillator.rs

@@ -37,6 +37,16 @@ impl Vco {
             ParamDescriptor { id: "freq_hz",  label: "Freq", min: 20.0, max: 20_000.0, default: 440.0, unit: "Hz", labels: &[] },
             ParamDescriptor { id: "waveform", label: "Wave", min: 0.0,  max: 4.0,      default: 1.0,   unit: "",   labels: &["Sine", "Saw", "Sqr", "Tri", "Pls"] },
         ],
+        description: "\
+## VCO — Voltage-Controlled Oscillator
+
+Generates a periodic audio-rate waveform at the set frequency.
+
+**Waveforms:** Sine · Saw · Square · Triangle · Pulse
+
+**Freq** sets the base pitch. Connect an LFO or keyboard CV to `cv_freq_hz` for 1 V/oct pitch modulation (0 V = 440 Hz, +1 V = 880 Hz).
+
+**Typical chain:** VCO Out → Filter In → VCA In → Output In",
     };
 
     #[inline]

crates/synth-core/src/vca.rs

@@ -22,6 +22,16 @@ impl Vca {
         params: &[
             ParamDescriptor { id: "gain", label: "Gain", min: 0.0, max: 1.0, default: 1.0, unit: "", labels: &[] },
         ],
+        description: "\
+## VCA — Voltage-Controlled Amplifier
+
+Scales the audio level of a signal. Audio enters on **In** and exits at a controlled volume on **Out**.
+
+**Gain** knob sets the base level (0 = silence, 1 = unity gain).
+
+Connect an ADSR **Env** output to the `cv_gain` jack to apply an amplitude envelope — the CV value multiplies with the knob gain each sample.
+
+**Typical chain:** VCO Out → VCA In → Output In, with ADSR Env → VCA cv_gain",
     };
 }