Glossary
Alphabetical reference of terms used across FrankenTUI’s codebase and documentation. Each entry is at most three sentences and links to its primary detail page.
A
Alpha-investing — Sequential FDR-control procedure that allocates a “wealth” budget to hypotheses and only spends alpha when rejecting one. Used to run many concurrent statistical monitors (BOCPD, CUSUM, conformal, e-process) without false-alarm inflation. See /intelligence/change-detection/alpha-investing.
Alt-screen — Terminal mode that switches to a separate alternate buffer; the original screen is restored on exit. FrankenTUI supports it but defaults to inline mode. See /concepts/screen-modes.
ANSI — American National Standards Institute, source of the terminal-
control encoding (ESC [ …) that FrankenTUI emits and parses. See
/reference/ansi-sequences.
B
Back buffer — The buffer being rendered to (the desired next state); compared against the front buffer to compute a diff. See /render/cell-and-buffer.
Bayes factor — Ratio of marginal likelihoods for two hypotheses; used in
FrankenTUI’s resize coalescer to decide between steady and burst
regimes. See
/intelligence/bayesian-inference/diff-strategy.
BOCPD — Bayesian Online Change-Point Detection; Adams & MacKay’s run- length-posterior algorithm used by the resize coalescer to detect regime changes online. See /intelligence/change-detection/bocpd.
Buffer — 2D row-major array of Cells representing display state. The
back buffer is diffed against the front buffer each frame. See
/render/cell-and-buffer.
BufferDiff — Algorithm that computes the set of changed cells between two buffers; implements Theorem 2 in the safety & correctness proof sketches.
C
Cell — 16-byte record at one grid position: content (char or
GraphemeId), fg, bg, and style attrs. The canonical unit of rendering. See
/render/cell-and-buffer.
ChangeRun — Contiguous horizontal span of changed cells, used by the presenter as the unit of ANSI emission. See /render/diff.
Cmd — Enum of side effects returned by Model::update; executed by the
effect queue rather than run synchronously. See
/runtime/commands.
Command Palette — Fuzzy-find widget that ranks commands via a Bayesian evidence ledger combining recency, frequency, and user preference. See /widgets/command-palette.
Conformal prediction — Distribution-free method that converts point predictions into prediction sets with a guaranteed marginal coverage probability. FrankenTUI uses Mondrian conformal prediction for frame-time risk gating. See /intelligence/conformal-prediction/mondrian.
CSI — Control Sequence Introducer, ESC [; starts the majority of ANSI
escape sequences. See /reference/ansi-sequences.
CUP / CHA — CUP (CSI {r};{c} H) moves the cursor to an absolute row
and column; CHA (CSI {c} G) moves to a column within the current row. See
/reference/ansi-sequences.
CUSUM — Cumulative Sum chart; a classic SPC technique used by FrankenTUI as a hover stabilizer and in budget-alert pipelines. See /intelligence/change-detection/cusum.
D
Damped spring — Critically-damped harmonic oscillator used by FrankenTUI’s animation system to produce smooth settling without overshoot. See /core/events-and-input.
DECSTBM — DEC Set Top and Bottom Margin (CSI {top};{bottom} r). Scopes
scrolling to a region; used by the inline-mode scroll-region strategy. See
/concepts/screen-modes.
DEC 2026 sync — Terminal synchronization mode (CSI ? 2026 h/l) that
batches output updates so the user sees atomic frame flips. See
ADR-002.
Diff strategy — Choice between full, dirty-row, and tile-skip buffer diffs, selected per frame via a Bayesian posterior. See /render/diff.
Dirty row / Dirty span — Row or horizontal span flagged as containing at least one changed cell. The presenter only emits output for dirty spans. See /render/diff.
Duty cycle — Fraction of wall time a process spends in a given regime (e.g. burst vs. steady); used in the resize coalescer. See /runtime/commands.
E
e-process — Anytime-valid test martingale: a non-negative process whose expectation is bounded by 1 under the null, enabling safe continuous monitoring. See /intelligence/e-processes.
Effect queue — Backpressure-aware queue that executes Cmds and emits
telemetry on queue depth, drops, and coalescing. See
/runtime/rollout/effect-queue.
Event — Raw terminal input in ftui-core: Key, Mouse, Resize,
Paste, Focus, Tick. Feeds both the model and the gesture recognizer. See
/core/events-and-input.
Evidence ledger — Structured record of scored candidates; used by the command palette to make its ranking auditable. See /widgets/command-palette.
Evidence sink — JSONL file or stdout destination that receives deterministic decision logs (diff strategy, resize, BOCPD). See /runtime/evidence-sink.
F
Fenwick tree — Binary-indexed tree for O(log n) prefix sums; powers the virtualized list widget’s height prediction. See /widgets/virtualized-list.
Focus graph — Directed graph that drives Tab-order traversal in the a11y and focus-management subsystems. See /a11y-i18n/focus-graph.
Frame — Render-pass object combining a Buffer, cursor position, and hit
grid; represents the desired terminal state for one tick. See
/render/frame.
Frame budget — Per-frame time target (default 16ms for 60 FPS); drives the degradation cascade when exceeded. See /operations/frame-budget.
G
GRAPA — Generalized Rank-based Anytime-valid Procedure; the framework underlying FrankenTUI’s e-process budget alerts. See /intelligence/e-processes.
GraphemeId — 32-bit reference to an interned grapheme cluster in the
GraphemePool. Encodes pool slot (24 bits) + display width (7 bits) so most
cells can avoid a pool lookup. See
/render/grapheme-pool.
Grapheme pool — Reference-counted interned storage for complex grapheme clusters that don’t fit in 4 bytes. See /render/grapheme-pool.
H
Hyperlink (OSC 8) — Terminal-level clickable link: ESC ] 8 ; ; URL ST
opens, ESC ] 8 ; ; ST closes. FrankenTUI tracks link state per cell. See
/widgets/hyperlinks.
I
Inline mode — Default screen mode that preserves scrollback and pins the UI to a fixed region. See /concepts/screen-modes.
IVM — Incremental View Maintenance; propagates deltas through a DAG of
operators rather than recomputing entire views. Used in FrankenTUI’s
RenderPlan. See /intelligence/ivm.
J
Jain’s fairness index — Ratio (Σxᵢ)² / (n · Σxᵢ²) measuring how evenly a
resource is shared; used by the input guard to detect render work starving
input processing. See
/widgets/observability-widgets.
K
Kitty keyboard protocol — Progressive keyboard-reporting extension that disambiguates escape codes and reports press/release/repeat events. See /reference/ansi-sequences.
L
Lens — Compositional getter/putter satisfying GetPut and PutGet laws; used
in ftui-runtime to focus updates on a subfield of the model. See
/runtime/lenses.
Live region — ARIA-inspired a11y concept: a region whose changes should be announced to assistive tech. FrankenTUI emits live-region updates via the accessibility tree. See /a11y-i18n/a11y-tree.
M
Magnetic docking — Pane-snap behavior where a dragged pane snaps to neighboring edges; includes a ghost preview. See /layout/panes/magnetic-docking.
Model (trait) — Elm-style trait Model<Message> with init/update/view;
the core of the runtime programming model. See
/runtime/model-trait.
MPC — Model Predictive Control; used in ftui-runtime to evaluate
control-policy candidates for budget pacing. See
/intelligence/control-theory.
O
One-writer rule — Invariant that only one entity writes to stdout at a
time; enforced by TerminalWriter ownership. See
/operations/one-writer-rule.
Operation (pane) — Discrete pane-tree mutation (split, close, resize) recorded on the operations timeline for undo/redo/replay. See /layout/panes/operations-and-timeline.
OSC 8 — See Hyperlink.
P
PAC-Bayes — Generalization bound framework used to validate FrankenTUI’s Bayesian ranking choices. See /intelligence/bayesian-inference/hint-ranking.
Pane (HSplit/VSplit/Leaf) — Node of the PaneTree: a split is an internal
node, a leaf holds a widget. See
/layout/panes/pane-tree.
PaneTree — Binary tree of Panes that describes the workspace layout.
Drag-resize and magnetic docking operate on this tree. See
/layout/panes/pane-tree.
PID / PI — Proportional-Integral(-Derivative) controller used for frame- budget pacing; FrankenTUI tunes gains for 16ms targets. See /intelligence/control-theory.
Presenter — State-tracked ANSI emitter that converts a Frame into bytes
on the wire; implements the reset+apply strategy from ADR-002. See
/render/presenter.
ProgramConfig — Builder for runtime configuration (screen mode, mouse policy, evidence sink, rollout lane). See /runtime/program-config.
R
RAII — Resource Acquisition Is Initialization; cleanup is tied to
Drop. TerminalSession::Drop restores raw mode and features even on panic.
See /core/terminal-session.
Raw mode — Terminal mode with unbuffered input; keys are delivered immediately without line-editing. See /core/terminal-session.
Rollout lane — One of Legacy, Structured, or Asupersync; selects the
runtime execution backend for shadow runs and migration. See
/runtime/rollout/lanes.
Rope — Balanced tree of text chunks backing the text editor; supports O(log n) insertions and splits. See /text/rope.
Rough-path signature — Truncated Chen-series signature of a path; used by FrankenTUI’s gesture system for trajectory-aware inputs. See /intelligence/rough-path-signatures.
S
S3-FIFO — Sieve/Stochastic/Small FIFO cache admission policy; used in the grapheme-pool admission cache. See /render/grapheme-pool.
SAT — Summed-Area Table; 2D prefix-sum for O(1) rectangle queries. Powers the tile-skip diff path. See /render/diff.
Scissor stack — Push/pop stack of clipping rectangles with monotonically decreasing intersection; prevents child clips from enlarging parents’. See /render/frame.
Screen mode — Inline (preserves scrollback) or AltScreen (full-
screen). See /concepts/screen-modes.
Scrollback — Terminal history buffer above the active view. Inline mode is scrollback-safe; alt-screen is not. See /concepts/screen-modes.
Session (terminal) — See TerminalSession.
Shadow run — Running two runtime lanes in parallel and comparing frame checksums to prove semantic equivalence. See /runtime/rollout/shadow-run.
Smith’s rule — SRPT/WSPT scheduling heuristic weight / time; used in the
effect-queue prioritizer. See /intelligence/scheduling.
Snapshot test — Test that compares byte-exact output against a saved
.txt or .jsonl baseline. Update with BLESS=1 cargo test. See
/testing/snapshot-tests.
SOS barrier — Sum-of-squares polynomial barrier certificate used for frame-budget admissibility; precomputed offline via semidefinite programming. See /intelligence/sos-barrier.
SRPT — Shortest Remaining Processing Time; scheduling discipline used by the effect queue. See /intelligence/scheduling.
Stylesheet — Named-style registry for the cascading style system. See /style/stylesheet.
Subscription — Declarative event source (ticks, IO, resize) reconciled by the runtime each frame. See /runtime/subscriptions.
Summed-area table — See SAT.
T
TableTheme — 3,500-line theming engine for the Table widget; handles
row/col striping, header styling, selection. See
/style/table-theme.
Telemetry schema — Canonical OTEL event/span schema; versioned 1.0.0.
See /reference/telemetry-events.
TerminalCapabilities — Detected terminal features: color profile, mux presence, sync output, kitty keyboard. Drives inline-mode strategy. See /core/capabilities.
TerminalSession — RAII guard that owns terminal state and restores it on
Drop, even under panic. See /core/terminal-session.
TerminalWriter — Single gate for all terminal output; enforces the one- writer rule. See /operations/one-writer-rule.
Test martingale — Non-negative process whose expectation under the null is bounded by 1; the formal device underlying e-processes. See /intelligence/e-processes.
Timeline (pane) — History of pane operations enabling undo/redo/replay. See /layout/panes/operations-and-timeline.
V
VOI — Value of Information; the expected decision utility gain from an additional sample. FrankenTUI uses VOI sampling to pick which hints/commands to re-rank. See /intelligence/voi-sampling.
W
WCAG 2.1 contrast — Web Content Accessibility Guidelines 2.1 contrast ratios (AA = 4.5:1 body, AAA = 7:1). FrankenTUI ships contrast-check utilities. See /a11y-i18n/contrast-checking.
Widget — Implementor of the Widget trait; renders itself into a Frame
within a given Rect. See /widgets/traits.
WidgetId — Opaque identifier for a widget instance; used by the focus manager and hit grid. See /widgets/focus.
W-TinyLFU — Window-TinyLFU cache admission policy, used in the width cache. See /text/grapheme-width.
Z
ZWJ — Zero Width Joiner (U+200D); Unicode combining mark that joins graphemes into compound emojis (e.g. family emoji). See /text/normalization.