User Guide

The operator's manual — workflow-first.

The operator's manual. Workflow-first: each chapter walks through something you can actually do with Sirius. Read in order if you're new; jump to the chapter you need otherwise.

For the conceptual model, design philosophy, and architectural rationale, see the white paper. The white paper says why the system works the way it does. This guide says how to make music with it.

Glossary

These terms appear throughout the guide. Pin them down once here.

Term	Meaning
Tape	The always-running recording of one input. Every audio input has a tape that is continuously capturing while Sirius is open. Tapes are infrastructure — you usually don't see them in the normal view. They make retroactive capture possible.
Input	One audio source. A guitar plugged into channel 1, a microphone, a synthesizer plugged into channel 2 — each is an input, and each input has its own tape.
Phrase	A musical thought you've captured. A verse, a chorus, an intro, a fill. A Phrase is a container; it holds Loops (and can hold sub-Phrases). Phrases carry musical meaning — role, intent, how they begin and end.
Loop	A specific slice of a tape that's part of a Phrase. The actual audio. Loops are leaves — they don't contain anything else; they point at a slice of audio on a specific tape. Every Loop lives inside a Phrase.
Pill	The colored rounded shape on the timeline. Each Pill is the visual rendering of one Phrase.
CaptureRegion	The temporary bookmark made by a Mark In / Mark Out gesture. Internal — you don't normally see it. The system immediately turns it into a Loop (and a Phrase, if needed).
Mark In	The gesture that marks the start of a captured region.
Mark Out	The gesture that marks the end of a captured region. Auto-promotes the captured region into the song.
Arm	Standing the system up so capture gestures take effect. Disarmed = nothing captures, no surprises. Armed = the next Mark In / Mark Out will land.
Playhead	The current time position. Where you are in the song.
LMC	"Local Machine Clock" — the system's continuous time reference. The unit on the Tape rulers. You don't usually need to think about LMC; the playhead and the song timeline handle this for you.

Chapter 1 — Capturing Phrases and Loops

The capture gesture

Every capture is the same three-step sequence:

Arm — tap the Arm button (or the per-input Arm in the Preparation tab). The button turns red. The system is now listening for capture gestures. Until you arm, nothing captures — Sirius starts disarmed on purpose, so you never capture by surprise.
Mark In — at the moment you want the captured region to start, tap Mark In. The system records the playhead position as the in-point. Visually, you'll see Mark Out become available.
Mark Out — at the moment you want the captured region to end, tap Mark Out. The system closes the region, and immediately promotes it into the song.

You can re-tap Mark In before Mark Out — that replaces the in-point without losing the armed state. You can also switch which input you're capturing onto in between Mark In and Mark Out, by tapping a different input's row.

What Mark Out does — the auto-promotion rule

When Mark Out fires, Sirius decides what to do with the captured region based on the playhead position at the moment of Mark In:

Mark In was outside any existing Phrase → Sirius mints a new Phrase containing the captured Loop, and adds it to the song. A new Pill appears on the timeline.
Mark In was inside an existing Phrase's span → Sirius adds the captured Loop as a child of that Phrase. No new Pill — the existing Pill quietly gains another layer.

This is the rule for everything. There's no "create phrase" button versus "create loop" button. The same physical gesture (Mark In → Mark Out) means different things based on whether you're inside an existing Phrase or not.

Diagram — outside any Phrase

Timeline (empty so far):
   0s    4s    8s   12s   16s   20s
   ┃     │     │     │     │     │
         Mark In here       Mark Out here
         (no Phrase exists)

Result:
   0s    4s    8s   12s   16s   20s
   ┃     ╭─────new Phrase─────╮
         │  (with one Loop)   │
         ╰────────────────────╯

Diagram — inside an existing Phrase

Timeline (a Verse Phrase already exists):
   0s    4s    8s   12s   16s   20s
   ┃     ╭─────────Verse──────────╮
         │                         │
         Mark In here  Mark Out here
         (inside Verse)

Result:
   0s    4s    8s   12s   16s   20s
   ┃     ╭─────────Verse──────────╮
         │       (now with        │
         │        one more Loop)  │
         ╰─────────────────────────╯

When the captured region straddles a Phrase boundary

If your Mark In was inside a Phrase but your Mark Out lands past the Phrase's end (or vice versa), Mark In wins — the captured region is treated as belonging to the Phrase that contained Mark In. The Loop's boundaries are clamped to fit within the host Phrase.

The reasoning: Mark In is the moment you committed to the capture; Mark Out is just where you stopped. If you intended a different Phrase as the host, hit Undo and try again with the playhead in the right place.

Recovering from an early Mark Out

If you hit Mark Out by accident, too soon, or you don't like what just landed, Undo is non-destructive of your capture state. Two ways to undo:

Tap the CaptureBanner that just appeared. The banner shows what was captured (Loop added to Verse · 3.6 s · tape #200 or Phrase 3 captured · 3.6 s · tape #200) and includes a small ↶ Undo affordance on the right. Tap it within the 1.5-second window the banner is visible.
Tap the bottom-bar Undo button. Always works.

After undoing a promotion, Sirius restores the capture session to its state before Mark Out: your Mark In is intact, the system is armed and awaiting an out-point. The tape never stopped recording — it has all the samples between Mark In and where you (mistakenly) marked out, and beyond. So you can immediately tap Mark Out again at the right moment, or tap Disarm to abandon the capture entirely.

In short: hitting Mark Out early costs you a single tap to recover. It does not cost you the capture itself.

Building a song from one instrument, then layering instruments on top

A natural workflow that uses the auto-promotion rule end-to-end.

Pass 1 — lay down the song structure on one instrument

Plug a guitar into input 1. Arm input 1.

Play through the song's sections, one at a time, with Mark Out at the end of each:

0s ──── play intro ──── Mark Out  (Phrase 1: Intro)
       ──── play verse ──── Mark Out  (Phrase 2: Verse)
       ──── play chorus ──── Mark Out  (Phrase 3: Chorus)
       ──── play bridge ──── Mark Out  (Phrase 4: Bridge)
                                        ...

Each Mark Out is outside any existing Phrase (you're building forward in time on a fresh timeline), so each mints a fresh Phrase. By the end of Pass 1 you have a row of Phrases on the timeline, each with one Loop child pointing at the guitar tape.

Pass 2 — overdub layers

Plug a bass into input 2. Arm input 2. Scrub the playhead back to song-time zero. Play along through the song.

As the playhead crosses each Phrase's span, hit Mark In (start of bass part) and Mark Out (end of bass part). Because Mark In is now inside an existing Phrase, each capture lands as a Loop child of that Phrase — no new Pills appear, but each Phrase quietly gains a bass layer.

Repeat for piano, drums, vocals, or anything else. Each pass adds Loops to the existing Phrases.

What's deferred (Roadmap)

Repeating song sections (verse × 3 sharing common layers, with per-instance vocal differences). The data and architecture for this is being designed in a separate spec; until then, each Phrase appears in the song exactly once.
A normally-hidden tapes view with an explicit "show tapes" affordance. Today the Preparation tab still surfaces tape rows by default. Future versions move tapes underneath a phrase-centric primary view.
Naming and editing Phrases. Today minted Phrases get a default role of capture and an empty name; editing the name / role / intent / grammar is a future Preparation-pane feature.
Capture-history widget. Superseded by auto-promotion — captures are now Pills on the timeline, which serve the same need as a history list.