Design notes#

The house style is phosphor: green on black, box-drawing frames, dim labels and bright values. Panels shrink to fit their content rather than filling the window.

┌─ WALLET ────────────────────────────────────────────────┐
│ addr        RXyz9k2mP…7Qa4                              │
│ tip         ▸ 3,481,207        node ✓ api.verustest.net │
├─────────────────────────────────────────────────────────┤
│ SPENDABLE  312.50000000  VRSCTEST  (4 utxos)            │
│ WITHHELD     6.00000000  VRSCTEST  (1 coinbase)         │
├─ TOKENS ────────────────────────────────────────────────┤
│ 1200.00000000  pecu@    iJhCe4Ap7…y8Kd                  │
│    0.50000000  bridge@  i3f7QwErT…V2Lm                  │
├─ PENDING ───────────────────────────────────────────────┤
│ in flight   2 transactions                              │
│ INCOMING   0.25000000  VRSCTEST                         │
│ OUTGOING   1.00010000  VRSCTEST                         │
│ NET       -0.75010000  VRSCTEST                         │
└─────────────────────────────────────────────────────────┘
  ▸ pending: in this node's mempool, not in any block, and excluded from the totals above

It is deliberately readable when piped. --theme plain drops the frames, the colour and the box-drawing entirely; --theme auto (the default) picks plain whenever stdout is not a terminal; NO_COLOR always wins; and --json will bypass the renderer completely once commands have data to serialise.

--theme light is the same layout in dark ink, for a terminal with a light background — phosphor is unreadable there and no terminal profile can fix it, because every colour it asks for is a 256-colour index outside the sixteen slots a profile can remap. Nine roles, each measured against white at 4.5:1 or better and pinned by a test rather than asserted in prose. auto never chooses it: the background of a terminal cannot be asked about reliably, so it is something you say (--theme light, or PECU_THEME) rather than something pecu guesses.

$ pecu dev ui --theme plain
WALLET
  addr        RXyz9k2mP...7Qa4
  tip         - 3,481,207        node ok api.verustest.net

  SPENDABLE  312.50000000  VRSCTEST  (4 utxos)
  WITHHELD     6.00000000  VRSCTEST  (1 coinbase)

pecu dev ui renders every widget in the kit — it is both the design reference and what the snapshot tests read, so a change to the renderer shows up as a diff rather than as a surprise somewhere else. Run make gallery to see it in colour.

Nothing outside src/ui/ emits an escape sequence or a box-drawing character. Commands describe what a block contains; the renderer decides how it looks.

Design notes#

• Keys never leave the machine. The SDK is offline-first by construction: the transaction builders open no sockets. Signing happens locally; only finished bytes go to the node.
• The SDK has no generate() on purpose — the caller supplies entropy. That job belongs to the keystore, which is why pecu key gen exists rather than a library call.
• Money is integer satoshis end to end. No floats, anywhere.
• The SDK dependency is pinned by commit. It is pre-1.0 and not on crates.io, so "latest main" would not be a reproducible build. pecu --version prints the rev.