newt-tui 0.8.0

//! `/settings` — **one typed form for the knob space** (#1981 slice 1).
//!
//! The operator's directive: aggressively reduce the slash surface. The line
//! that decides each command is **a verb that merely SETS A VALUE is absorbed;
//! a verb that PERFORMS something stays** — and `/vi`, `/emacs`, `/nano`,
//! `/edit-mode` are four verbs for one enum-valued setting.
//!
//! # Why a form and not a fifth verb
//!
//! A form is an `InteractionDefinition`, so it renders through C0's plain
//! projection, through the RichTUI span projection, and on the web — none of
//! which a slash verb does. `crew_form` (D1a, #1885) is the precedent this
//! copies rather than reinvents: the flow is a sequence of definitions asked
//! through C1's seam, so it never carries a private console path and the unit
//! tier stays fully mocked by injecting [`Ask`].
//!
//! **No panel this slice.** `/settings` ships through the plain/typed path
//! only. RegionLease (#1986) has landed and a leased inline panel is a later
//! upgrade; a chooser you drive blind is not a consolidation.
//!
//! # One mutation path, and now one receipt (#1965)
//!
//! [`apply`] is the only place a setting changes, and it is PRIVATE.
//! [`apply_and_record`] is the only way to reach it: the form, a deep link
//! (`/settings edit-mode vi`), the deprecated verbs (`/vi`), the dial setters
//! (`/psyche tenacity`) and `/psyche obsessive` all go through it, and each
//! one writes a content-addressed `newt_core::settings_receipt` line.
//!
//! That privacy is the design. Slash commands reached no receipt path at all —
//! thirty-four commands mutating session state with nothing durable behind
//! them, which is how a round-cap escalation to effectively unlimited left no
//! record in config, receipts, turns or artifacts. Collapsing the knob verbs
//! into one chokepoint is what turned "instrument thirty-four call sites" into
//! "instrument one", and making the mutation unreachable without the recorder
//! is what stops the thirty-fifth from reintroducing the gap.
//!
//! # The deprecated verbs still work
//!
//! Operators have muscle memory. `/vi` does not become "unknown command" and
//! does not become a lecture — it applies the setting AND names where the
//! setting now lives. Routing it through [`apply`] rather than leaving the old
//! arm in place is what keeps "one mutation path" true rather than aspirational.

use newt_core::interaction_surface::SurfaceInteraction;
use newt_core::settings_receipt::SettingChange;
use newt_core::HumanQuestionOutcome;
use newt_interaction::InteractionDefinition;

/// How the form reaches the operator: C1's seam, and nothing wider — the same
/// type `crew_form` uses, for the same reason.
pub(crate) type Ask<'a> = &'a dyn Fn(&SurfaceInteraction) -> HumanQuestionOutcome;

/// A setting `/settings` carries.
///
/// Two families so far: the editor mode (slice 1) and the effort dials (this
/// slice). Every one of them is enum-valued with a small closed vocabulary,
/// which is exactly the shape the operator's line singles out — *a verb that
/// merely SETS A VALUE is absorbed; a verb that PERFORMS something stays*.
///
/// `/psyche` is therefore NOT absorbed: its panel and its status view perform,
/// and they keep performing. What moved here is its two text setters, which
/// only ever set. See `docs/decisions/slash_command_target_set.md`.
/// What a field will accept.
///
/// Four of the five settings are a closed vocabulary, and a menu is the right
/// surface for those. The round cap is a NUMBER, so it gets a text field —
/// widening the form rather than bolting a second dispatch beside it, which is
/// what forced `/rounds` to keep its own unrecorded write until now.
pub(crate) enum ValueSpace {
    /// A closed vocabulary, rendered as a menu of `(value, what it means)`.
    Choice(Vec<(&'static str, String)>),
    /// A number in `min..=max`, plus one token that RELEASES the setting back
    /// to its derived default (`auto`).
    Number {
        release: &'static str,
        min: usize,
        max: usize,
    },
    /// **Free text, taken verbatim.**
    ///
    /// Not a vocabulary and not a number: a prompt template is whatever the
    /// operator typed, trailing space and all. `release` releases the setting
    /// back to config the way `auto` does for a number, so "go back to my
    /// `[tui] prompt`" stays a value rather than becoming a second verb.
    ///
    /// The important half is in `run`: a `Text` field reads the RAW remainder
    /// of the line, because trimming it would silently eat the trailing space
    /// in `/settings prompt "❯ "` — which is the single most likely template
    /// anyone writes.
    Text {
        release: &'static str,
        placeholder: &'static str,
    },
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum Field {
    EditMode,
    Tenacity,
    Initiative,
    Cognition,
    Thinking,
    Nudge,
    Markdown,
    Mode,
    Prompt,
    Compaction,
    Detail,
    Posture,
    Rounds,
    Prefix,
    GitAuthor,
    GitConfig,
    GitSigning,
}

impl Field {
    /// Every field the form offers, menu order.
    pub(crate) const ALL: &'static [Self] = &[
        Self::EditMode,
        Self::Tenacity,
        Self::Initiative,
        Self::Cognition,
        Self::Thinking,
        Self::Nudge,
        Self::Markdown,
        Self::Mode,
        Self::Prompt,
        Self::Compaction,
        Self::Detail,
        Self::Posture,
        Self::Rounds,
        Self::Prefix,
        Self::GitAuthor,
        Self::GitConfig,
        Self::GitSigning,
    ];

    /// The deep-link token: `/settings <name> [value]`. This is ALSO the
    /// registry's command name, which is what lets `apply` ask the registry
    /// where this setting's receipt lands rather than carrying a second list.
    pub(crate) fn name(self) -> &'static str {
        match self {
            Self::EditMode => "edit-mode",
            Self::Tenacity => "tenacity",
            Self::Initiative => "initiative",
            Self::Cognition => "cognition",
            Self::Thinking => "thinking",
            Self::Nudge => "nudge",
            Self::Markdown => "markdown",
            Self::Mode => "mode",
            Self::Prompt => "prompt",
            Self::Compaction => "compaction",
            Self::Detail => "detail",
            Self::Posture => "posture",
            Self::Rounds => "rounds",
            Self::Prefix => "prefix",
            Self::GitAuthor => "git-author",
            Self::GitConfig => "git-config",
            Self::GitSigning => "git-signing",
        }
    }

    pub(crate) fn label(self) -> &'static str {
        match self {
            Self::EditMode => "line-editor key bindings",
            Self::Tenacity => "tenacity",
            Self::Initiative => "initiative",
            Self::Cognition => "cognition",
            Self::Thinking => "reasoning display",
            Self::Nudge => "action-pressure nudges",
            Self::Markdown => "markdown rendering",
            Self::Mode => "operating mode",
            Self::Prompt => "input prompt template",
            Self::Compaction => "automatic-compaction trigger",
            Self::Detail => "tool-output detail rows",
            Self::Posture => "permission posture",
            Self::Rounds => "tool-call round limit",
            Self::Prefix => "meta prefix key",
            Self::GitAuthor => "sandbox git commit author",
            Self::GitConfig => "sandbox git settings",
            Self::GitSigning => "harness commit signing",
        }
    }

    /// The allowed values, as `(value, what it means)`.
    ///
    /// The dial levels and their descriptions come from `Tenacity::all()` /
    /// `Initiative::all()` / `Cognition::all()` — the same lists `/psyche …
    /// list` renders. A second
    /// hand-written copy here is how the form and the dial would drift apart
    /// the first time a level is added.
    pub(crate) fn value_space(self) -> ValueSpace {
        use newt_core::role_profile::Cognition;
        use newt_core::{Initiative, Tenacity};
        let owned = |pairs: &[(&'static str, &str)]| -> ValueSpace {
            ValueSpace::Choice(pairs.iter().map(|(v, d)| (*v, (*d).to_string())).collect())
        };
        match self {
            Self::EditMode => owned(&[
                ("vi", "modal editing (default)"),
                ("emacs", "emacs-style editing"),
                ("nano", "nano-style editing"),
            ]),
            Self::Tenacity => ValueSpace::Choice(
                std::iter::once(("auto", "normal, unless set explicitly".to_string()))
                    .chain(
                        Tenacity::all()
                            .into_iter()
                            .map(|t| (t.label(), t.describe())),
                    )
                    .collect(),
            ),
            Self::Initiative => ValueSpace::Choice(
                std::iter::once((
                    "auto",
                    "inherit from the persona / config / model family".to_string(),
                ))
                .chain(
                    Initiative::all()
                        .into_iter()
                        .map(|i| (i.label(), i.describe())),
                )
                .collect(),
            ),
            Self::Cognition => ValueSpace::Choice(
                std::iter::once(("auto", "follow the active persona (default)".to_string()))
                    .chain(std::iter::once((
                        "off",
                        "send no reasoning controls, overriding any persona".to_string(),
                    )))
                    .chain(
                        Cognition::all()
                            .into_iter()
                            .map(|c| (c.label(), c.describe().to_string())),
                    )
                    .collect(),
            ),
            Self::Thinking => owned(&[
                (
                    "fold",
                    "bounded reasoning, then how long it thought (default)",
                ),
                ("stream", "every reasoning line, unbounded"),
                ("off", "just the answer"),
            ]),
            Self::Nudge => owned(&[
                ("on", "action-pressure steering enabled (default)"),
                ("off", "no narration rescue / workflow repair / plan pushes"),
            ]),
            // `auto` is a real choosable value, not the absence of one: it
            // means "follow colour", which is a different state from `on`
            // on a pipe. The absorbed verb offered all three and so does this.
            // Each choice says what it would shadow, because that is the
            // whole trade: tmux/herdr semantics on a chord of your choosing.
            Self::GitAuthor => owned(&[
                (
                    "agent",
                    "the agent identity, so sandbox commits never pass for yours (default)",
                ),
                ("operator", "your own git name and email"),
            ]),
            Self::GitConfig => owned(&[
                ("baseline", "git's own defaults; nothing copied (default)"),
                (
                    "environment",
                    "copy your ~/.gitconfig's plain settings now (never aliases, credentials or includes)",
                ),
            ]),
            Self::GitSigning => owned(&[
                ("off", "newt's commits are unsigned (default)"),
                (
                    "harness",
                    "a harness key newt holds (created if `signing_key` is unset)",
                ),
                (
                    "operator",
                    "your own git signing key (user.signingkey, gpg.format)",
                ),
            ]),
            Self::Prefix => owned(&[
                ("ctrl+space", "collides with nothing in newt (default)"),
                (
                    "ctrl+a",
                    "GNU Screen's; shadows line-start in emacs/nano editing",
                ),
                (
                    "ctrl+b",
                    "tmux's and herdr's own; inside them it reaches them first",
                ),
                ("ctrl+n", "shadows next-line in emacs editing"),
            ]),
            Self::Markdown => owned(&[
                ("auto", "render when colour is active (default)"),
                ("on", "always render (still needs colour)"),
                ("off", "stream raw text"),
            ]),
            // **Built from the enum, not typed out beside it.** The styles,
            // their order and their one-line descriptions all live on
            // `OperatingMode`; a style added there appears here without an
            // edit, which is the whole reason the type moved to core.
            Self::Mode => ValueSpace::Choice(
                newt_core::operating_mode::OperatingMode::all()
                    .iter()
                    .map(|m| (m.as_str(), m.description().to_string()))
                    .collect(),
            ),
            // Built from the enum's own keywords, so a policy added to
            // `CompactionTriggerPolicy` shows up here without an edit.
            Self::Compaction => ValueSpace::Choice(vec![
                (
                    newt_core::CompactionTriggerPolicy::HeadroomAware.keyword(),
                    "defer a count-only compaction while input headroom is known (default)"
                        .to_string(),
                ),
                (
                    newt_core::CompactionTriggerPolicy::MessageCount.keyword(),
                    "compact whenever the message count exceeds its threshold".to_string(),
                ),
            ]),
            Self::Prompt => ValueSpace::Text {
                release: "reset",
                placeholder: "\"[$TIME] ❯ \"",
            },
            // A count, like the round cap — and for the same reason: the
            // absorbed verb takes `/spill <rows>` with any number, so a
            // vocabulary could not represent the state the operator can
            // already reach.
            //
            // `0` is this knob's UNBOUNDED, which is what `/detail` toggles to
            // and what `--trace` installs. `auto` releases back to
            // `[tui] spill_lines`. The maximum is a formality — a `Number`
            // field must declare one, and no terminal has a hundred thousand
            // rows of useful scrollback.
            // **The vocabulary is the operator's config, read at ask time.**
            // A posture is whatever `[modes.<name>]` they wrote, so a static
            // list could only ever be wrong. `off` releases the clamp — the
            // same word `/posture off` uses.
            Self::Posture => {
                let mut options = vec![("off", "no posture — release the clamp".to_string())];
                if let Ok(cfg) =
                    crate::migration_notices::read(|report| newt_core::Config::resolve(report))
                {
                    for (name, m) in &cfg.modes {
                        let what = m.preset.as_ref().map_or_else(
                            || "guidance only (no permission clamp)".to_string(),
                            |p| format!("clamped by preset '{p}'"),
                        );
                        // Leaked deliberately: `ValueSpace::Choice` holds
                        // `&'static str`, and these names come from a config
                        // read at ask time. One small leak per opened form is
                        // the cost of a runtime-seeded vocabulary; the
                        // alternative is a static list that cannot describe
                        // the operator's own config.
                        options.push((Box::leak(name.clone().into_boxed_str()) as &str, what));
                    }
                }
                ValueSpace::Choice(options)
            }
            Self::Detail => ValueSpace::Number {
                release: "auto",
                min: 0,
                max: 100_000,
            },
            // The one field that is not a vocabulary. `/rounds double` and
            // `/rounds unlimited` stay affordances of the VERB — they are
            // relative operations, not values — and the verb resolves them to a
            // number before it lands here.
            Self::Rounds => ValueSpace::Number {
                release: "auto",
                min: 1,
                max: newt_core::tenacity::RELENTLESS_TOOL_ROUND_TARGET,
            },
        }
    }

    /// What this setting is right now, through the one resolver that already
    /// owns the precedence rather than a second reading of it.
    ///
    /// For the dials that means the OVERRIDE, not the effective level: the
    /// setting is what this form can change, and `auto` is a real, choosable
    /// value that resolution then fills in.
    pub(crate) fn current(self) -> String {
        use newt_core::cognition::cli_cognition;
        match self {
            Self::Prefix => prefix_setting(),
            Self::GitAuthor => git_profile().author.as_str().to_string(),
            Self::GitConfig => git_profile().config_source.as_str().to_string(),
            Self::GitSigning => git_profile().signing.as_str().to_string(),
            Self::EditMode => match crate::prompt::resolve_edit_mode() {
                newt_core::EditMode::Vi => "vi",
                newt_core::EditMode::Emacs => "emacs",
                newt_core::EditMode::Nano => "nano",
            }
            .to_string(),
            // Through the one dial→token mapping, which the typed doors also
            // use to report what they changed.
            Self::Tenacity => tenacity_token(newt_core::tenacity::cli_tenacity()),
            Self::Initiative => initiative_token(newt_core::initiative::cli_initiative()),
            Self::Cognition => cognition_token(cli_cognition()),
            // Three states now, so this reports the mode rather than
            // collapsing `fold` and `stream` into one "on".
            Self::Thinking => {
                match crate::migration_notices::read(newt_core::agentic::thinking_mode) {
                    newt_core::ThinkingMode::Fold => "fold",
                    newt_core::ThinkingMode::Stream => "stream",
                    newt_core::ThinkingMode::Off => "off",
                }
                .to_string()
            }
            Self::Nudge => if nudges_off() { "off" } else { "on" }.to_string(),
            // The OVERRIDE, like the dials — `auto` is what this form can set
            // and what resolution then fills in from colour.
            Self::Markdown => {
                crate::migration_notices::read(newt_core::config::session_markdown_mode)
                    .keyword()
                    .to_string()
            }
            Self::Mode => newt_core::operating_mode::session_operating_mode()
                .as_str()
                .to_string(),
            // The TEMPLATE, not the rendered preview: the setting is what this
            // form can change, and the preview is what resolution makes of it.
            Self::Prompt => crate::prompt::active_prompt_template(),
            Self::Compaction => {
                crate::migration_notices::read(newt_core::config::session_compaction_trigger_policy)
                    .keyword()
                    .to_string()
            }
            // The OVERRIDE, like the dials: `auto` is a real choosable value
            // that resolution then fills in from `[tui] spill_lines`.
            Self::Detail => newt_core::config::session_spill_lines()
                .map_or_else(|| "auto".to_string(), |n| n.to_string()),
            Self::Posture => {
                newt_core::posture::active_posture().map_or_else(|| "off".to_string(), |p| p.name)
            }
            Self::Rounds => newt_core::tenacity::session_tool_rounds()
                .map_or_else(|| "auto".to_string(), |n| n.to_string()),
        }
    }

    /// This setting's value **with whatever provenance it has** — the payload a
    /// receipt records (#1998).
    ///
    /// For every token-valued field that is just the token. For the round cap
    /// it is the whole `ToolRoundLimit`, because a cap without the number it
    /// was measured against is precisely the record #1965 found missing. It
    /// falls back to the token when no config baseline has been installed:
    /// "unknown" is an honest answer, an invented `configured` is not.
    fn value_now(self) -> newt_core::settings_receipt::SettingValue {
        use newt_core::settings_receipt::SettingValue;
        match self {
            Self::Rounds => newt_core::tenacity::session_tool_round_limit()
                .map_or_else(|| SettingValue::Token(self.current()), SettingValue::from),
            _ => SettingValue::Token(self.current()),
        }
    }

    /// Whether this field's value is FREE TEXT rather than a vocabulary.
    ///
    /// Asked by `help_request`: a template may legitimately contain `help` or
    /// `-h`, so `/settings prompt "help me"` must not be swallowed by the help
    /// interceptor. The carve-out asks the field instead of carrying a third
    /// hardcoded name beside `start` and `rename` — a list that had already
    /// gone stale by missing `/name` (#2009 PR5).
    pub(crate) fn takes_free_text(self) -> bool {
        matches!(self.value_space(), ValueSpace::Text { .. })
    }

    /// Resolve a deep-link token to a field.
    pub(crate) fn from_token(token: &str) -> Option<Self> {
        Self::ALL
            .iter()
            .copied()
            .find(|f| f.name().eq_ignore_ascii_case(token))
    }

    /// Whether `value` is one this field accepts, normalized.
    ///
    /// The alias arms are not politeness — each one was accepted by the verb
    /// this field absorbed, and absorbing a command must not silently drop an
    /// affordance operators already type.
    pub(crate) fn accepts(self, value: &str) -> Option<String> {
        let want = value.trim().to_lowercase();
        // **The mode aliases live on the enum**, which already owns
        // `developer`/`sysadmin`/`diagnostic`/`full_auto`. Listing them again
        // in the arms below would be a second copy of a vocabulary this slice
        // moved to core precisely so there could be one.
        if matches!(self, Self::Mode) {
            return newt_core::operating_mode::OperatingMode::from_keyword(&want)
                .map(|m| m.as_str().to_string());
        }
        let want = match (self, want.as_str()) {
            // `/edit-mode vim`
            (Self::EditMode, "vim") => "vi",
            // `/psyche tenacity inherit|reset`
            (Self::Tenacity | Self::Initiative, "inherit" | "reset") => "auto",
            // `/thinking on` predates the three-way vocabulary and meant
            // "show me the reasoning". It still does; that is now `fold`.
            (Self::Thinking, "on") => "fold",
            // `/psyche cognition none` / `reset` / `persona`
            (Self::Cognition, "none") => "off",
            (Self::Cognition, "reset" | "persona") => "auto",
            // `/rounds reset|default` release the override, the same word the
            // dials use for the same act.
            (Self::Rounds, "reset" | "default") => "auto",
            // `/spill reset|default|config` release this one — every word the
            // absorbed verb already accepted for the same act.
            (Self::Detail, "reset" | "default" | "config") => "auto",
            // `/detail`'s unbounded, said in words rather than as a bare `0`.
            (Self::Detail, "full" | "unbounded" | "all") => "0",
            // `/markdown always|never` — the keywords `MarkdownMode` has
            // always aliased. Absorbing a verb must not drop an affordance
            // operators already type.
            (Self::Markdown, "always") => "on",
            (Self::Markdown, "never") => "off",
            _ => want.as_str(),
        };
        match self.value_space() {
            ValueSpace::Choice(values) => values
                .into_iter()
                .find(|(v, _)| *v == want)
                .map(|(v, _)| v.to_string()),
            // Verbatim, from the ORIGINAL — `want` is lowercased, and a
            // template is not case-insensitive. One layer of surrounding
            // quotes comes off, which is what lets a trailing space be typed
            // at all.
            ValueSpace::Text { release, .. } => {
                let raw = crate::prompt::strip_one_quote_pair(value);
                if raw.trim().eq_ignore_ascii_case(release) || raw.trim().is_empty() {
                    Some(release.to_string())
                } else {
                    Some(raw.to_string())
                }
            }
            ValueSpace::Number { release, min, max } => {
                if want == release {
                    return Some(release.to_string());
                }
                // Canonical decimal, so `/settings rounds 0050` and
                // `/settings rounds 50` are one value with one address.
                want.parse::<usize>()
                    .ok()
                    .filter(|n| (min..=max).contains(n))
                    .map(|n| n.to_string())
            }
        }
    }

    /// The tokens this field offers, for tests that check the vocabulary is the
    /// dial's own rather than a second copy. Empty for a numeric field.
    #[cfg(test)]
    fn offered(self) -> Vec<&'static str> {
        match self.value_space() {
            ValueSpace::Choice(values) => values.into_iter().map(|(v, _)| v).collect(),
            ValueSpace::Number { release, .. } | ValueSpace::Text { release, .. } => {
                vec![release]
            }
        }
    }

    /// What this field accepts, said in one line — the refusal message, and the
    /// text field's hint.
    pub(crate) fn accepts_hint(self) -> String {
        match self.value_space() {
            ValueSpace::Choice(values) => values
                .into_iter()
                .map(|(v, _)| v)
                .collect::<Vec<_>>()
                .join(", "),
            ValueSpace::Number { release, min, max } => {
                format!("{release}, or a number from {min} to {max}")
            }
            ValueSpace::Text {
                release,
                placeholder,
            } => format!("{release}, or a template like {placeholder}"),
        }
    }
}

/// The one reading of the nudge dial — `NEWT_NUDGE=off` disables it, anything
/// else (including unset) leaves it on.
pub(crate) fn nudges_off() -> bool {
    std::env::var("NEWT_NUDGE").is_ok_and(|v| v.eq_ignore_ascii_case("off"))
}

/// The top-level form: which setting to change, each showing its current value.
pub(crate) fn field_menu() -> InteractionDefinition {
    let entries: Vec<(String, String)> = Field::ALL
        .iter()
        .enumerate()
        .map(|(i, f)| {
            (
                (i + 1).to_string(),
                format!("{} — currently {}", f.label(), f.current()),
            )
        })
        .collect();
    let refs: Vec<(&str, &str)> = entries
        .iter()
        .map(|(k, v)| (k.as_str(), v.as_str()))
        .collect();
    newt_core::interaction_form::menu("settings", "Esc cancels", &refs)
}

/// The second step: which value for `field`.
pub(crate) fn value_menu(field: Field) -> InteractionDefinition {
    let current = field.current();
    let ValueSpace::Choice(values) = field.value_space() else {
        // A number has no menu to pick from, so the form asks for it — still a
        // typed `InteractionDefinition`, so it still renders on the plain
        // scroller, the RichTUI and the web.
        return newt_core::interaction_form::text_field(
            format!("{} — currently {current}", field.label()),
            format!("{} · Esc cancels", field.accepts_hint()),
        );
    };
    let entries: Vec<(String, String)> = values
        .into_iter()
        .enumerate()
        .map(|(i, (value, what))| {
            let mark = if value == current { "  (current)" } else { "" };
            ((i + 1).to_string(), format!("{value} — {what}{mark}"))
        })
        .collect();
    let refs: Vec<(&str, &str)> = entries
        .iter()
        .map(|(k, v)| (k.as_str(), v.as_str()))
        .collect();
    newt_core::interaction_form::menu(field.label(), "Esc cancels", &refs)
}

/// The meta prefix as the operator names it: `NEWT_PREFIX_KEY` (this
/// session), else `[tui] prefix_key`, else `ctrl+space`. The ONE owner of that
/// precedence — the panel driver parses this same string (`prefix::configured`).
pub(crate) fn prefix_setting() -> String {
    std::env::var("NEWT_PREFIX_KEY")
        .ok()
        .filter(|value| !value.trim().is_empty())
        .or_else(|| {
            crate::migration_notices::read(|report| newt_core::Config::resolve_unpublished(report))
                .ok()
                .and_then(|c| c.tui)
                .and_then(|t| t.prefix_key)
        })
        .unwrap_or_else(|| "ctrl+space".to_string())
}

/// Write one `[tui]` scalar to the operator's config, preserving the rest.
fn persist_tui_key(key: &str, value: &str) -> Result<(), String> {
    let path = newt_core::Config::user_config_path()
        .ok_or_else(|| "no config directory to save the setting in".to_string())?;
    let text = config_fs::read(&path);
    let updated = newt_core::Config::with_tui_key(&text, key, value).map_err(|e| e.to_string())?;
    config_fs::write(&path, &updated).map_err(|e| format!("saving {key}: {e}"))
}

/// The config file, as a seam: the unit tier never touches a real file.
#[cfg(not(test))]
mod config_fs {
    pub(super) fn read(path: &std::path::Path) -> String {
        std::fs::read_to_string(path).unwrap_or_default()
    }
    pub(super) fn write(path: &std::path::Path, text: &str) -> std::io::Result<()> {
        std::fs::write(path, text)
    }
}

#[cfg(test)]
pub(crate) mod config_fs {
    use std::cell::RefCell;
    use std::path::{Path, PathBuf};

    thread_local! {
        static FILES: RefCell<Vec<(PathBuf, String)>> = const { RefCell::new(Vec::new()) };
    }

    pub(crate) fn read(path: &Path) -> String {
        FILES.with(|files| {
            files
                .borrow()
                .iter()
                .rev()
                .find(|(p, _)| p == path)
                .map(|(_, text)| text.clone())
                .unwrap_or_default()
        })
    }

    pub(crate) fn write(path: &Path, text: &str) -> std::io::Result<()> {
        FILES.with(|files| {
            files
                .borrow_mut()
                .push((path.to_path_buf(), text.to_string()));
        });
        Ok(())
    }
}

/// **THE ONE MUTATION PATH.** Every route — the form, a deep link, a
/// deprecated verb, `/psyche tenacity`, `/psyche obsessive` — lands here.
///
/// **Private on purpose.** The receipt attaches in [`apply_and_record`], and a
/// caller that could reach the write without it would be the #1965 gap with
/// extra steps. The module's own tests call this directly, because what they
/// are checking is the mutation, not the record.
///
/// The `#1668` posture marks are made HERE, beside the write, for the same
/// reason: a caller that sets the dial and forgets to mark the axis leaves the
/// conversation's operator pin stale, and there is now exactly one caller.
fn apply(field: Field, value: &str) -> Result<String, String> {
    use newt_core::cognition::CognitionOverride;
    use newt_core::role_profile::Cognition;
    use newt_core::{Initiative, Tenacity};

    let Some(value) = field.accepts(value) else {
        return Err(format!(
            "/settings {} takes {}",
            field.name(),
            field.accepts_hint()
        ));
    };
    let value = value.as_str();
    match field {
        // Under the process-env lock (#1850); the editor is rebuilt right
        // after a slash command returns, before further input is read.
        Field::EditMode => newt_core::process_env::set_var("NEWT_EDIT_MODE", value),
        // `auto` is the only value that does not parse as a level, because
        // `accepts` already refused everything else. Both dials parse their
        // token and hand it to the SAME writer the typed door uses, so the two
        // routes cannot drift in what they set or what they pin.
        Field::Tenacity => write_tenacity(value.parse::<Tenacity>().ok()),
        Field::Initiative => write_initiative(value.parse::<Initiative>().ok()),
        Field::Cognition => write_cognition(match value {
            "auto" => CognitionOverride::Unset,
            "off" => CognitionOverride::Off,
            level => level
                .parse::<Cognition>()
                .map_or(CognitionOverride::Unset, CognitionOverride::Set),
        }),
        Field::Thinking => newt_core::process_env::set_var("NEWT_THINKING", value),
        // Written the same way `/markdown` writes it, under the #1850 lock,
        // and read back through the one resolver that owns the precedence.
        Field::Markdown => newt_core::process_env::set_var("NEWT_MARKDOWN", value),
        // `accepts` has already resolved the token through `from_keyword`, so
        // this cannot fail — and it goes through the SAME setter `/mode` uses.
        // The session loop clears the stale model-selected style when it sees
        // this value change; see `chat.rs`'s reconcile beside
        // `dispatch_slash_with_ask`.
        Field::Mode => {
            if let Some(mode) = newt_core::operating_mode::OperatingMode::from_keyword(value) {
                newt_core::operating_mode::set_session_operating_mode(mode);
            }
        }
        // `on` REMOVES the variable rather than setting it, which is what the
        // absorbed `/nudge on` did: the readers test for `=off`, so an unset
        // variable and `on` are the same state and only one of them is a
        // leftover for the next `/nudge status` to explain.
        Field::Nudge => {
            if value == "off" {
                newt_core::process_env::set_var("NEWT_NUDGE", "off");
            } else {
                newt_core::process_env::remove_var("NEWT_NUDGE");
            }
        }
        // `auto` releases the override so the cap derives from tenacity +
        // config again; anything else is a number `accepts` has already
        // bounded, so the parse cannot fail.
        Field::Rounds => newt_core::tenacity::set_session_tool_rounds(value.parse::<usize>().ok()),
        // `reset` removes the variable rather than storing the word, so the
        // session falls back to `[tui] prompt` and no leftover survives for
        // the next `/prompt` to explain — the same shape `/nudge on` uses.
        // Resolved by the SAME `build_posture` the verb calls, over the same
        // config-rooted skill dirs, and installed through the one writer — so
        // `/posture` and `/settings posture` cannot install different
        // bindings. A posture that fails to resolve installs NOTHING: it is
        // atomic-or-nothing, and `accepts` has already bounded the name to one
        // the config declares.
        Field::Posture => {
            if value == "off" {
                newt_core::posture::set_active_posture(None);
            } else {
                let cfg =
                    crate::migration_notices::read(|report| newt_core::Config::resolve(report))
                        .map_err(|e| e.to_string())?;
                let dirs = cfg.skill_search_dirs();
                let posture = newt_core::posture::build_posture(value, &cfg, |skill| {
                    newt_skills::load_body_from(&dirs, skill)
                })
                .map_err(|e| e.to_string())?;
                newt_core::posture::set_active_posture(Some(posture));
            }
        }
        // Through the same writer `/spill` and `/detail` use, so the three
        // doors onto this one knob cannot disagree.
        Field::Detail => {
            newt_core::config::set_session_spill_lines(value.parse::<usize>().ok());
        }
        // Through the same writer `/context compaction` uses.
        Field::Compaction => {
            if let Some(policy) = newt_core::CompactionTriggerPolicy::from_keyword(value) {
                newt_core::process_env::set_var("NEWT_COMPACTION_TRIGGER", policy.keyword());
            }
        }
        Field::Prompt => {
            if value == "reset" {
                newt_core::process_env::remove_var("NEWT_PROMPT");
            } else {
                newt_core::process_env::set_var("NEWT_PROMPT", value);
            }
        }
        // The one field here that PERSISTS: a prefix you had to set again every
        // session would be a trap. `[tui] prefix_key`, through the
        // comment-preserving writer; and the session, so the next panel uses it
        // at once.
        // Persisted to the operator's `agent-identity.toml`: the shell reads
        // it on every dispatch, so the next command already uses it.
        Field::GitAuthor => persist_git_profile(|git| {
            git.author = if value == "operator" {
                newt_core::agent_identity::SandboxAuthor::Operator
            } else {
                newt_core::agent_identity::SandboxAuthor::Agent
            };
            Ok(())
        })?,
        // Choosing `environment` takes the snapshot NOW, so choosing it again
        // is how the operator refreshes it.
        Field::GitConfig => persist_git_profile(|git| {
            if value == "environment" {
                let listing = newt_core::git_hardening::ambient_git_config_listing()
                    .map_err(|e| format!("could not read your git config: {e}"))?;
                git.config = newt_core::git_hardening::copyable_git_config(&listing);
                git.config_source = newt_core::agent_identity::GitConfigSource::Environment;
            } else {
                git.config.clear();
                git.config_source = newt_core::agent_identity::GitConfigSource::Baseline;
            }
            Ok(())
        })?,
        // `harness` with no `signing_key` creates one, and says where its
        // public half goes, because a signature nobody can verify is noise.
        Field::GitSigning => {
            let mut created = None;
            persist_identity(|identity| {
                use newt_core::agent_identity::SigningMode;
                identity.git.signing = match value {
                    "harness" => SigningMode::Harness,
                    "operator" => SigningMode::Operator,
                    _ => SigningMode::Off,
                };
                if value == "harness" && identity.signing_key.is_none() {
                    let dir = newt_core::Config::user_config_dir()
                        .ok_or("no config directory for the harness key")?;
                    let path = dir.join("harness-signing.pem");
                    created = Some(newt_core::commit_signing::generate_harness_key(&path)?);
                    identity.signing_key = Some(path.to_string_lossy().into_owned());
                }
                Ok(())
            })?;
            if let Some(public) = created {
                return Ok(format!(
                    "{}: {value}\nnew harness key; add this to the agent's GitHub account \
                     as a signing key so its commits verify:\n{public}",
                    field.label()
                ));
            }
        }
        Field::Prefix => {
            persist_tui_key("prefix_key", value)?;
            newt_core::process_env::set_var("NEWT_PREFIX_KEY", value);
            #[cfg(feature = "rich-tui")]
            crate::prefix::invalidate();
        }
    }
    Ok(format!("{}: {value}", field.label()))
}

/// The sandbox git profile in force (`[agent-identity.git]`).
fn git_profile() -> newt_core::agent_identity::GitProfile {
    newt_core::AgentIdentity::resolve().unwrap_or_default().git
}

/// Edit the sandbox git profile in the operator's own `agent-identity.toml`,
/// keeping every other field of that file as it was.
fn persist_git_profile(
    edit: impl FnOnce(&mut newt_core::agent_identity::GitProfile) -> Result<(), String>,
) -> Result<(), String> {
    persist_identity(|identity| edit(&mut identity.git))
}

/// Edit the operator's own `agent-identity.toml`, keeping every other field.
fn persist_identity(
    edit: impl FnOnce(&mut newt_core::AgentIdentity) -> Result<(), String>,
) -> Result<(), String> {
    let path = newt_core::AgentIdentity::user_identity_path()
        .ok_or("no home directory to hold agent-identity.toml")?;
    let mut identity = if path.is_file() {
        newt_core::AgentIdentity::load(&path).map_err(|e| e.to_string())?
    } else {
        newt_core::AgentIdentity::default()
    };
    edit(&mut identity)?;
    identity.save(&path).map_err(|e| e.to_string())
}

/// The change a transition is recorded as, or `None` when the registry
/// declares no destination for this setting.
///
/// **This is the production reader of the registry's receipt column.** The
/// decision is data, not a call site's memory: a field is receipted because
/// `slash_registry` says where its receipt lands. A `Receipt::Missing` field
/// writes nothing and stays counted in the #1965 debt, which is the honest
/// answer — a receipt sent to a destination nobody declared looks like
/// coverage without being any.
///
/// Pure, so the whole decision is exercised with no filesystem: the write
/// itself belongs to `settings_receipt::record`.
fn change_for(
    setting: &str,
    from: newt_core::settings_receipt::SettingValue,
    to: newt_core::settings_receipt::SettingValue,
    via: &str,
) -> Option<SettingChange> {
    match crate::slash_registry::receipt_for(setting) {
        crate::slash_registry::Receipt::Journal => Some(SettingChange::new(setting, from, to, via)),
        _ => None,
    }
}

/// **THE ONE ROUTE OUT.** Apply a setting and durably record that it happened.
///
/// [`apply`] is private precisely so this cannot be bypassed: a caller that
/// could reach the mutation without the receipt is the #1965 defect with extra
/// steps, and there were thirty-four of those. `via` is the verb the operator
/// actually typed — `/vi` and `/settings edit-mode` produce the same setting
/// and two different events, and the route is the half a reader cannot
/// reconstruct afterwards.
///
/// A no-op (`/vi` when already `vi`) is recorded too. The journal records what
/// the operator DID, and "asked for vi, was already vi" is a fact about the
/// session, not noise to be filtered by a rule nobody can see.
///
/// Recording is best effort by construction (`settings_receipt::record`
/// swallows its own failures): failing to observe a change must never undo the
/// change.
pub(crate) fn apply_and_record(field: Field, value: &str, via: &str) -> Result<String, String> {
    recorded(field, via, || apply(field, value)).map(|(message, _)| message)
}

/// Snapshot the setting, run the write, record what moved.
///
/// The recording half of [`apply_and_record`], factored out because there is
/// now a second door — a TYPED one, for callers that hold a dial rather than a
/// token (see [`apply_cognition`]). Two doors, ONE recorder: a second copy of
/// this five-line dance is exactly how one of them would quietly stop
/// journalling.
fn recorded<T>(
    field: Field,
    via: &str,
    write: impl FnOnce() -> Result<T, String>,
) -> Result<(T, Option<SettingChange>), String> {
    recorded_values(field.name(), field.value_now(), via, || {
        let applied = write()?;
        Ok((applied, field.value_now()))
    })
}

/// Shared recorder for both process-owned fields and caller-owned tab state.
/// A failed write produces no receipt; every successful write consults the
/// same registry destination and stores the actual typed before/after values.
fn recorded_values<T>(
    setting: &str,
    from: newt_core::settings_receipt::SettingValue,
    via: &str,
    write: impl FnOnce() -> Result<(T, newt_core::settings_receipt::SettingValue), String>,
) -> Result<(T, Option<SettingChange>), String> {
    let (applied, to) = write()?;
    let change = change_for(setting, from, to, via);
    if let Some(change) = change.clone() {
        let _ = newt_core::settings_receipt::record(change);
    }
    Ok((applied, change))
}

/// **The typed door, for a caller holding a dial rather than a token.**
///
/// The `/psyche` panel has a `CognitionOverride` in hand and used to write it
/// straight through `set_cli_cognition`, which is the #1965 gap in the one
/// place best positioned to know better: a panel that changes a dial and
/// leaves no receipt. The obvious fix — render the dial to a token and call
/// [`apply_and_record`] — buys a `Result` the panel cannot report (its apply
/// runs inside `close_outcome`, which has no error arm), so an unaccepted
/// token would silently drop the operator's change. A typed door has no such
/// failure mode: the value is already the thing the runtime stores.
///
/// Same writer, same recorder, same posture mark as the token path — it is
/// literally the arm [`apply`] runs, called directly.
///
/// **`rich-tui`, to match its only caller.** The panel is the thing that holds
/// a typed dial, and the panel does not exist in a lean / headless / wyvern
/// build. The token door stays ungated, because slash commands do.
#[cfg(feature = "rich-tui")]
pub(crate) fn apply_cognition(
    choice: newt_core::cognition::CognitionOverride,
    via: &str,
) -> String {
    journalled_cognition(choice, via).0
}

/// [`apply_cognition`], also handing back the change it journalled.
///
/// **The change is returned so a test can SEE which setting was recorded.**
/// Without it the `Field` handed to [`recorded`] is unguarded: swapping
/// `Field::Cognition` for `Field::Tenacity` here leaves the runtime state
/// right, the returned message right (it is built from an explicit label),
/// and every source-scanning guard passing — while the journal gains a false
/// `tenacity` row whose from and to are equal, and the operator's real
/// cognition change is recorded nowhere. An adversarial review ran exactly
/// that mutation against the whole suite and got 1289 green.
///
/// It cannot be observed through the journal in the unit tier, deliberately:
/// `GlobalSettingsGuard` blanks `RECEIPT_PATH_ENV` so tests write no files.
/// Returning the value is what makes the claim checkable without one.
#[cfg(feature = "rich-tui")]
fn journalled_cognition(
    choice: newt_core::cognition::CognitionOverride,
    via: &str,
) -> (String, Option<SettingChange>) {
    // Infallible by construction, so the `Result` is unwrapped rather than
    // returned: `write_cognition` cannot fail, and a caller forced to handle
    // an impossible error would invent a behaviour for it.
    recorded(Field::Cognition, via, || {
        write_cognition(choice);
        // The message reads the resolver, which is the ONE place that renders
        // a dial as its token — a second rendering here would be a second
        // opinion about what `auto` is called.
        Ok(format!(
            "{}: {}",
            Field::Cognition.label(),
            Field::Cognition.current()
        ))
    })
    .unwrap_or_else(|never| (never, None))
}

/// The typed door for tenacity. `None` releases the override — `auto`.
#[cfg(feature = "rich-tui")]
pub(crate) fn apply_tenacity(level: Option<newt_core::Tenacity>, via: &str) -> String {
    journalled_tenacity(level, via).0
}

/// [`apply_tenacity`], also handing back the change it journalled — see
/// [`journalled_cognition`] for why that is returned rather than inferred.
#[cfg(feature = "rich-tui")]
fn journalled_tenacity(
    level: Option<newt_core::Tenacity>,
    via: &str,
) -> (String, Option<SettingChange>) {
    recorded(Field::Tenacity, via, || {
        write_tenacity(level);
        Ok(format!(
            "{}: {}",
            Field::Tenacity.label(),
            Field::Tenacity.current()
        ))
    })
    .unwrap_or_else(|never| (never, None))
}

/// The typed door for initiative. `None` releases the override — `auto`.
#[cfg(feature = "rich-tui")]
pub(crate) fn apply_initiative(level: Option<newt_core::Initiative>, via: &str) -> String {
    journalled_initiative(level, via).0
}

/// [`apply_initiative`], also handing back the change it journalled — see
/// [`journalled_cognition`] for why that is returned rather than inferred.
#[cfg(feature = "rich-tui")]
fn journalled_initiative(
    level: Option<newt_core::Initiative>,
    via: &str,
) -> (String, Option<SettingChange>) {
    recorded(Field::Initiative, via, || {
        write_initiative(level);
        Ok(format!(
            "{}: {}",
            Field::Initiative.label(),
            Field::Initiative.current()
        ))
    })
    .unwrap_or_else(|never| (never, None))
}

/// Apply only to the caller's active tab. Style cannot mark cognition,
/// tenacity, initiative, model preferences or change capability-bearing persona metadata.
#[cfg(feature = "rich-tui")]
pub(crate) fn apply_personality(
    current: &mut newt_core::role_profile::PersonalityTraits,
    next: newt_core::role_profile::PersonalityTraits,
    via: &str,
) -> String {
    journalled_personality(current, next, via).0
}

#[cfg(feature = "rich-tui")]
fn journalled_personality(
    current: &mut newt_core::role_profile::PersonalityTraits,
    next: newt_core::role_profile::PersonalityTraits,
    via: &str,
) -> (String, Option<SettingChange>) {
    recorded_values("psyche", (*current).into(), via, || {
        *current = next;
        let to = newt_core::settings_receipt::SettingValue::from(*current);
        Ok((format!("personality overrides: {to}"), to))
    })
    .unwrap_or_else(|never| (never, None))
}

/// The runtime write for cognition, and the posture mark that must accompany
/// it. Private: every route in reaches it through [`recorded`].
fn write_cognition(choice: newt_core::cognition::CognitionOverride) {
    newt_core::cognition::set_cli_cognition(choice);
    // #1668: setting a dial pins its axis as an operator preference.
    newt_core::runtime::mark_cognition_choice(choice);
}

fn write_tenacity(level: Option<newt_core::Tenacity>) {
    match level {
        Some(level) => newt_core::tenacity::set_cli_tenacity(level),
        None => newt_core::tenacity::clear_cli_tenacity(),
    }
    newt_core::runtime::mark_tenacity_choice(level);
}

fn write_initiative(level: Option<newt_core::Initiative>) {
    match level {
        Some(level) => newt_core::initiative::set_cli_initiative(level),
        None => newt_core::initiative::clear_cli_initiative(),
    }
    newt_core::runtime::mark_initiative_choice(level);
}

/// The vocabulary token for a dial position — the same string the menu offers
/// and `accepts` takes.
///
/// **The one mapping**, called by [`Field::current`] rather than duplicated
/// there. It was written as a second copy of that arm; a review named it, and
/// two renderings of "what is this dial called" is precisely how one of them
/// starts saying `inherit` where the other says `auto`.
fn cognition_token(choice: newt_core::cognition::CognitionOverride) -> String {
    use newt_core::cognition::CognitionOverride;
    match choice {
        CognitionOverride::Unset => "auto".to_string(),
        CognitionOverride::Off => "off".to_string(),
        CognitionOverride::Set(level) => level.label().to_string(),
    }
}

fn tenacity_token(level: Option<newt_core::Tenacity>) -> String {
    level.map_or_else(|| "auto".to_string(), |l| l.label().to_string())
}

fn initiative_token(level: Option<newt_core::Initiative>) -> String {
    level.map_or_else(|| "auto".to_string(), |l| l.label().to_string())
}

/// What a deprecated verb prints in addition to doing its job.
pub(crate) fn moved_notice(verb: &str, field: Field) -> String {
    format!(
        "(/{verb} still works; this setting now lives in /settings {})",
        field.name()
    )
}

/// Drive `/settings [field] [value]`.
///
/// `rest` is everything after the command word. Empty opens the form; one
/// token deep-links to a field's value menu; two apply directly. Returns the
/// lines to print — the caller owns the terminal, this owns no I/O.
pub(crate) fn run(ask: Ask<'_>, rest: &str) -> Vec<String> {
    // `trim_end` only for the split: a trailing space belongs to a `Text`
    // value, so trimming the whole line here would eat it before anything
    // could decide whether it mattered.
    let mut parts = rest.trim_start().splitn(2, char::is_whitespace);
    let first = parts.next().unwrap_or("").trim();
    let raw_second = parts.next().unwrap_or("");
    let second = raw_second.trim();

    // `/settings <field> <value>` — no question needed.
    if !first.is_empty() {
        let Some(field) = Field::from_token(first) else {
            let known: Vec<&str> = Field::ALL.iter().map(|f| f.name()).collect();
            return vec![format!(
                "/settings has no `{first}` setting (have: {})",
                known.join(", ")
            )];
        };
        // **The deep link carries the quoted template verbatim** (#2009 PR5).
        //
        // This is the parsing the `/prompt set` verb owned, ported rather than
        // reinvented: everything after the field name is the literal value,
        // taken from the RAW remainder so internal and trailing spaces
        // survive, with one layer of surrounding quotes stripped by `accepts`.
        //
        // `/settings prompt "❯ "` is the case that decides it. Trimming turns
        // it into `❯`, which renders flush against whatever the operator
        // types, and nothing in the pipeline would report the difference.
        let is_text = matches!(field.value_space(), ValueSpace::Text { .. });
        let value = if is_text { raw_second } else { second };
        if !value.trim().is_empty() {
            return vec![match apply_and_record(field, value, "/settings") {
                Ok(msg) | Err(msg) => msg,
            }];
        }
        return ask_value(ask, field);
    }

    // Bare `/settings` — pick a field, then a value.
    let menu = field_menu();
    let Some(choice) = ask_choice(ask, &menu) else {
        return vec!["settings: cancelled".to_string()];
    };
    let Some(index) = choice.parse::<usize>().ok().filter(|i| *i >= 1) else {
        return vec!["settings: cancelled".to_string()];
    };
    let Some(field) = Field::ALL.get(index - 1).copied() else {
        return vec!["settings: cancelled".to_string()];
    };
    ask_value(ask, field)
}

fn ask_value(ask: Ask<'_>, field: Field) -> Vec<String> {
    ask_and_apply(ask, field, "/settings")
}

/// Ask for one field's value and apply it through [`apply_and_record`],
/// recorded as reached `via` (`/settings`, `/setup`). Setup asks the git
/// profile through this, so its questions and its write are `/settings`' own.
pub(crate) fn ask_and_apply(ask: Ask<'_>, field: Field, via: &str) -> Vec<String> {
    let cancelled = || vec!["settings: cancelled".to_string()];
    let definition = value_menu(field);
    let value = match field.value_space() {
        // A number is taken as typed; `apply` is the one validator, so the
        // form does not grow a second opinion about what is in range.
        ValueSpace::Number { .. } => {
            let interaction = SurfaceInteraction::blocking(definition.clone());
            let HumanQuestionOutcome::Answer(answer) = ask(&interaction) else {
                return cancelled();
            };
            let answer = answer.trim().to_string();
            // An empty line is backing out, not an invalid number.
            if answer.is_empty() {
                return cancelled();
            }
            answer
        }
        // Free text, taken as typed — `accepts` is the one validator, and for
        // a template it accepts anything, so the form grows no second opinion
        // about what a prompt may contain.
        ValueSpace::Text { .. } => {
            let interaction = SurfaceInteraction::blocking(definition.clone());
            let HumanQuestionOutcome::Answer(answer) = ask(&interaction) else {
                return cancelled();
            };
            // NOT trimmed: `"❯ "` is the likeliest template anyone types and
            // its trailing space is the point. An empty line is backing out.
            if answer.trim().is_empty() {
                return cancelled();
            }
            answer
        }
        ValueSpace::Choice(values) => {
            let Some(choice) = ask_choice(ask, &definition) else {
                return cancelled();
            };
            let Some(index) = choice.parse::<usize>().ok().filter(|i| *i >= 1) else {
                return cancelled();
            };
            let Some((value, _)) = values.get(index - 1) else {
                return cancelled();
            };
            (*value).to_string()
        }
    };
    vec![match apply_and_record(field, &value, via) {
        Ok(msg) | Err(msg) => msg,
    }]
}

/// Ask one menu and return the chosen option id, or `None` when the operator
/// backed out. The resolution is `interaction_form::resolve`'s, not a second
/// parser.
fn ask_choice(ask: Ask<'_>, definition: &InteractionDefinition) -> Option<String> {
    let interaction = SurfaceInteraction::blocking(definition.clone());
    match ask(&interaction) {
        HumanQuestionOutcome::Answer(answer) => {
            newt_core::interaction_form::resolve(definition, answer.trim())
                .map(|id| id.as_str().to_string())
        }
        _ => None,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Every test that reaches [`apply_and_record`] holds this. It serializes
    /// the process-global dials AND turns the receipt journal off, so a unit
    /// test cannot append to the developer's real `~/.newt/receipts.jsonl` —
    /// which it did until the guard learned about the journal.
    fn settings_guard() -> newt_core::test_guard::GlobalSettingsGuard {
        newt_core::test_guard::GlobalSettingsGuard::acquire()
    }

    /// A scripted operator. The `Ask` seam is injected, so the whole form is
    /// exercised with no terminal, no I/O and no real prompt — the unit tier
    /// stays fully mocked, which is the reason `crew_form`'s shape was copied
    /// rather than a private console path invented.
    fn answering(
        answers: &'static [&'static str],
    ) -> impl Fn(&SurfaceInteraction) -> HumanQuestionOutcome {
        let next = std::cell::Cell::new(0usize);
        move |_| {
            let i = next.get();
            next.set(i + 1);
            answers.get(i).map_or(HumanQuestionOutcome::Cancelled, |a| {
                HumanQuestionOutcome::Answer((*a).to_string())
            })
        }
    }

    /// Like [`answering`] but for answers built at runtime (a field index, a
    /// typed number).
    fn answering_owned(
        answers: Vec<String>,
    ) -> impl Fn(&SurfaceInteraction) -> HumanQuestionOutcome {
        let next = std::cell::Cell::new(0usize);
        move |_| {
            let i = next.get();
            next.set(i + 1);
            answers.get(i).map_or(HumanQuestionOutcome::Cancelled, |a| {
                HumanQuestionOutcome::Answer(a.clone())
            })
        }
    }

    fn declining() -> impl Fn(&SurfaceInteraction) -> HumanQuestionOutcome {
        |_| HumanQuestionOutcome::Cancelled
    }

    /// **Deep link: `/settings edit-mode vi` asks nothing and applies.**
    #[test]
    fn a_full_deep_link_applies_without_a_question() {
        let _g = settings_guard();
        let asked = std::cell::Cell::new(false);
        let ask = |_: &SurfaceInteraction| {
            asked.set(true);
            HumanQuestionOutcome::Cancelled
        };
        let out = run(&ask, "edit-mode emacs");
        assert!(!asked.get(), "a fully-specified deep link must not prompt");
        assert_eq!(out, vec!["line-editor key bindings: emacs".to_string()]);
        assert_eq!(Field::EditMode.current(), "emacs");
    }

    /// The two-step form: pick the field, then the value.
    #[test]
    fn the_form_walks_field_then_value() {
        let _g = settings_guard();
        // "1" selects the first field, "1" selects its first value (vi).
        let out = run(&answering(&["1", "1"]), "");
        assert_eq!(out, vec!["line-editor key bindings: vi".to_string()]);
        assert_eq!(Field::EditMode.current(), "vi");
    }

    /// **Anti-vacuous twin.** Every assertion above would hold over a form
    /// that applied unconditionally. Backing out changes nothing.
    #[test]
    fn cancelling_the_form_changes_no_setting() {
        let _g = settings_guard();
        let _ = apply(Field::EditMode, "nano");
        let before = Field::EditMode.current();
        let out = run(&declining(), "");
        assert_eq!(out, vec!["settings: cancelled".to_string()]);
        assert_eq!(
            Field::EditMode.current(),
            before,
            "a cancelled form must not write"
        );
    }

    /// A value the field does not accept is refused with the allowed set, and
    /// writes nothing.
    #[test]
    fn an_unaccepted_value_is_refused_and_writes_nothing() {
        let _g = settings_guard();
        let _ = apply(Field::EditMode, "vi");
        let err = apply(Field::EditMode, "ed").expect_err("`ed` is not an edit mode");
        assert!(err.contains("vi, emacs, nano"), "{err}");
        assert_eq!(Field::EditMode.current(), "vi", "a refusal must not write");
    }

    /// `vim` was accepted by the old `/edit-mode` arm. Absorbing a command
    /// must not silently drop an alias operators type.
    #[test]
    fn the_vim_alias_the_old_verb_took_still_resolves() {
        assert_eq!(Field::EditMode.accepts("vim").as_deref(), Some("vi"));
        assert_eq!(Field::EditMode.accepts("VI").as_deref(), Some("vi"));
        assert_eq!(Field::EditMode.accepts("ed"), None);
    }

    /// An unknown setting name lists what exists rather than failing silently.
    #[test]
    fn an_unknown_field_names_the_ones_that_exist() {
        let out = run(&declining(), "nosuchsetting");
        assert!(out[0].contains("no `nosuchsetting` setting"), "{out:?}");
        assert!(out[0].contains("edit-mode"), "{out:?}");
    }

    /// The menus are typed definitions, not printed strings — which is what
    /// makes them render on the plain scroller, the RichTUI and the web.
    #[test]
    fn the_menus_are_definitions_carrying_every_choice() {
        let _g = settings_guard();
        let menu = value_menu(Field::EditMode);
        let rendered = newt_core::markup::plain::render(&menu);
        for value in ["vi", "emacs", "nano"] {
            assert!(rendered.contains(value), "{value} missing: {rendered}");
        }
        assert!(
            rendered.contains("(current)"),
            "the current value is marked: {rendered}"
        );
        assert_eq!(field_menu().controls.len(), 1, "one choice control");
    }

    /// **Every dial the form claims reports the value its own resolver owns.**
    ///
    /// The knobs are process globals set through four different modules; a
    /// form that read them by hand would show a stale value the moment one
    /// module changed. Each `current()` goes through that module's reader.
    #[test]
    fn each_field_reports_what_its_own_resolver_says() {
        let _g = settings_guard();
        for (field, value) in [
            (Field::EditMode, "nano"),
            (Field::Tenacity, "relentless"),
            (Field::Initiative, "decisive"),
            (Field::Cognition, "thoughtful"),
            (Field::Thinking, "off"),
            (Field::Nudge, "off"),
        ] {
            apply(field, value).expect("an offered value applies");
            assert_eq!(field.current(), value, "{} did not read back", field.name());
        }
        // ...and every one of them goes back, which a write-only global would
        // not manage.
        for (field, value) in [
            (Field::Tenacity, "auto"),
            (Field::Initiative, "auto"),
            (Field::Cognition, "auto"),
            (Field::Thinking, "fold"),
            (Field::Nudge, "on"),
        ] {
            apply(field, value).expect("an offered value applies");
            assert_eq!(field.current(), value, "{} did not release", field.name());
        }
    }

    /// The dial levels come from the dial, not a second list in this file.
    ///
    /// Adding a `Tenacity` level must make it choosable here without anyone
    /// remembering to; a hand-copied list is how `/psyche … list` and the form
    /// would silently disagree.
    #[test]
    fn the_dial_levels_are_the_dials_own() {
        let offered = Field::Tenacity.offered();
        for level in newt_core::Tenacity::all() {
            assert!(offered.contains(&level.label()), "{level:?} not offered");
        }
        assert!(offered.contains(&"auto"), "the release value is missing");
        assert_eq!(offered.len(), newt_core::Tenacity::all().len() + 1);

        let offered = Field::Initiative.offered();
        for level in newt_core::Initiative::all() {
            assert!(offered.contains(&level.label()), "{level:?} not offered");
        }
        assert_eq!(offered.len(), newt_core::Initiative::all().len() + 1);

        let offered = Field::Cognition.offered();
        for level in newt_core::role_profile::Cognition::all() {
            assert!(offered.contains(&level.label()), "{level:?} not offered");
        }
        assert!(offered.contains(&"off") && offered.contains(&"auto"));
    }

    /// **Every alias the absorbed verbs took still resolves.** Each of these
    /// was reachable before the family moved; absorbing a command must not
    /// quietly delete an affordance operators already type.
    /// **Three doors onto one knob** (#2009 PR7b).
    ///
    /// `/spill <rows>`, `/detail` and `/settings detail` all set the session
    /// spill override. The code already claimed "one variable, so the launch
    /// flag and the runtime control cannot disagree"; absorbing it added a
    /// third door, and this is what keeps that claim true across all of them.
    #[test]
    fn the_detail_field_shares_one_knob_with_spill_and_the_toggle() {
        let _guard = settings_guard();
        newt_core::config::set_session_spill_lines(None);
        assert_eq!(Field::Detail.current(), "auto", "unpinned follows config");

        // The field sets it...
        assert_eq!(
            apply(Field::Detail, "12"),
            Ok("tool-output detail rows: 12".to_string())
        );
        assert_eq!(newt_core::config::session_spill_lines(), Some(12));

        // ...`/detail`'s toggle reads the SAME value and flips it to unbounded.
        let toggled = crate::toggle_spill_detail(newt_core::config::session_spill_lines(), 3);
        newt_core::config::set_session_spill_lines(toggled);
        assert_eq!(Field::Detail.current(), "0", "0 is this knob's unbounded");

        // ...and the field reports what the toggle did, with no second state.
        assert_eq!(newt_core::config::session_spill_lines(), Some(0));
    }

    /// `auto` releases; the launch flag's unbounded is a real value, not a
    /// release. Those are different states and the field keeps them apart.
    #[test]
    fn releasing_detail_is_not_the_same_as_setting_it_unbounded() {
        let _guard = settings_guard();

        apply(Field::Detail, "0").expect("0 is in range");
        assert_eq!(newt_core::config::session_spill_lines(), Some(0));
        assert_eq!(Field::Detail.current(), "0");

        apply(Field::Detail, "auto").expect("auto releases");
        assert_eq!(
            newt_core::config::session_spill_lines(),
            None,
            "release must REMOVE the override, not store a word"
        );
        assert_eq!(Field::Detail.current(), "auto");
    }

    /// Every word the absorbed verbs accepted for these two acts still works.
    #[test]
    fn the_detail_verbs_vocabulary_survives_absorption() {
        for word in ["reset", "default", "config"] {
            assert_eq!(
                Field::Detail.accepts(word),
                Some("auto".to_string()),
                "`/spill {word}` released the override"
            );
        }
        for word in ["full", "unbounded", "all"] {
            assert_eq!(Field::Detail.accepts(word), Some("0".to_string()), "{word}");
        }
        assert_eq!(Field::Detail.accepts("40"), Some("40".to_string()));
        assert_eq!(Field::Detail.accepts("-1"), None);
        assert_eq!(Field::Detail.accepts("banana"), None);
    }

    /// **`off` releases the clamp, and the field reports what is installed.**
    ///
    /// The posture field is the last of §5.1's relocations: the value lives in
    /// core, so a pure `apply` can install it. `off` is the same word
    /// `/posture off` uses — a released clamp is a value, not a second verb.
    #[test]
    fn the_posture_field_reports_and_releases_what_is_installed() {
        let _guard = settings_guard();
        newt_core::posture::set_active_posture(None);
        assert_eq!(Field::Posture.current(), "off");

        newt_core::posture::set_active_posture(Some(newt_core::posture::ActivePosture {
            name: "locked".to_string(),
            preset_name: "strict".to_string(),
            clamp: newt_core::Caveats::default(),
            clamp_summary: "deny writes".to_string(),
            skill_body: None,
            framing: None,
        }));
        assert_eq!(Field::Posture.current(), "locked");

        assert_eq!(
            apply(Field::Posture, "off"),
            Ok("permission posture: off".to_string())
        );
        assert!(
            newt_core::posture::active_posture().is_none(),
            "`off` releases the clamp rather than storing the word"
        );
    }

    /// Grounds the atomic resolver tests in the real config-loading and
    /// receipt path used by the settings form. A declared but invalid posture
    /// must neither change authority nor journal a successful setting change.
    #[tokio::test]
    async fn posture_settings_resolution_failure_is_not_a_success_receipt() {
        // Config::resolve also has unguarded readers and subprocess consumers
        // in this test binary. Keep this new NEWT_CONFIG fixture in a child,
        // so it cannot leak into another test's environment snapshot.
        const CHILD: &str = "NEWT_POSTURE_CONFIG_FIXTURE";
        if std::env::var_os(CHILD).is_none() {
            let fixture = tempfile::tempdir().unwrap();
            let config_dir = fixture.path().join(".newt");
            std::fs::create_dir_all(&config_dir).unwrap();
            let config = config_dir.join("config.toml");
            std::fs::write(&config, "[modes.broken]\npreset = 'missing'\n").unwrap();
            let mut command = tokio::process::Command::new(std::env::current_exe().unwrap());
            // Same three-axis policy as CLI common::isolate: an explicit
            // config alone does not stop the project walk or user drop-ins.
            for (key, _) in std::env::vars_os() {
                if key.to_string_lossy().starts_with("NEWT_") {
                    command.env_remove(key);
                }
            }
            for key in [
                "OPENAI_BASE_URL",
                "OPENAI_API_KEY",
                "OPENAI_MODEL",
                "OLLAMA_HOST",
            ] {
                command.env_remove(key);
            }
            command.args([
                    "--exact",
                    "settings_form::tests::posture_settings_resolution_failure_is_not_a_success_receipt",
                    "--nocapture",
                ])
                .current_dir(fixture.path())
                .env("HOME", fixture.path())
                .env("USERPROFILE", fixture.path())
                .env("NEWT_CONFIG_DIR", &config_dir)
                .env("NEWT_CONFIG", &config)
                .env(CHILD, "1")
                .stdin(std::process::Stdio::null())
                .kill_on_drop(true);
            let output = tokio::time::timeout(newt_core::test_guard::HANG_GUARD, command.output())
                .await
                .expect("settings fixture watchdog expired; child is killed on drop")
                .unwrap();
            assert!(
                output.status.success(),
                "isolated settings fixture failed: {}\n{}",
                String::from_utf8_lossy(&output.stdout),
                String::from_utf8_lossy(&output.stderr)
            );
            assert!(String::from_utf8_lossy(&output.stdout).contains("1 passed"));
            return;
        }
        let _guard = settings_guard();
        let receipts = std::env::current_dir().unwrap().join("receipts.jsonl");
        let saved_posture = newt_core::posture::active_posture();
        std::env::set_var(newt_core::settings_receipt::RECEIPT_PATH_ENV, &receipts);
        let previous = newt_core::posture::ActivePosture {
            name: "existing".into(),
            preset_name: "strict".into(),
            clamp: newt_core::Caveats::default(),
            clamp_summary: "deny writes".into(),
            skill_body: None,
            framing: Some("Keep the existing guidance.".into()),
        };
        newt_core::posture::set_active_posture(Some(previous.clone()));
        let result = apply_and_record(Field::Posture, "broken", "/settings posture");
        let installed = newt_core::posture::active_posture();
        newt_core::posture::set_active_posture(saved_posture);
        let error = result.expect_err("an unresolved preset must fail");
        assert!(
            error.contains("names preset 'missing'")
                && error.contains("[permission_presets.missing]"),
            "must reach the missing-preset resolver, not an unrelated config error: {error}"
        );
        let installed = installed.expect("failed resolution must preserve the old posture");
        assert_eq!(installed.name, previous.name);
        assert_eq!(installed.clamp, previous.clamp);
        assert_eq!(installed.framing, previous.framing);
        assert!(
            !receipts.exists(),
            "failed settings must not emit success receipts"
        );
    }

    /// The vocabulary is the operator's own config, read at ask time — a
    /// static list could only ever be wrong about `[modes.<name>]`.
    #[test]
    fn the_posture_vocabulary_always_offers_the_release() {
        let offered = Field::Posture.offered();
        assert!(
            offered.contains(&"off"),
            "releasing the clamp is always available: {offered:?}"
        );
        assert_eq!(offered.first().copied(), Some("off"), "and it leads");
    }

    /// **The verb and the field write one policy** (#2009 PR7).
    ///
    /// `/context compaction` set a `run_chat` local that
    /// `settings_form::apply` could not see. Both doors go through
    /// `NEWT_COMPACTION_TRIGGER` now, read back by the one resolver that owns
    /// the precedence.
    #[test]
    fn the_compaction_field_and_its_verb_resolve_to_one_state() {
        let _guard = settings_guard();
        newt_core::process_env::remove_var("NEWT_COMPACTION_TRIGGER");
        assert_eq!(
            Field::Compaction.current(),
            newt_core::CompactionTriggerPolicy::default().keyword(),
            "unpinned, the field reports what the resolver resolves"
        );

        assert_eq!(
            apply(Field::Compaction, "message_count"),
            Ok("automatic-compaction trigger: message_count".to_string())
        );
        assert_eq!(Field::Compaction.current(), "message_count");
        assert!(newt_core::config::compaction_trigger_is_session_pinned());
    }

    /// The field's vocabulary is the enum's, and only the enum's.
    #[test]
    fn the_compaction_fields_choices_are_the_policies_that_exist() {
        use newt_core::CompactionTriggerPolicy as P;
        let offered = Field::Compaction.offered();
        assert_eq!(
            offered,
            vec![P::HeadroomAware.keyword(), P::MessageCount.keyword()]
        );
        // A policy the enum does not have is refused, not stored.
        assert_eq!(Field::Compaction.accepts("aggressive"), None);
        // ...and the canonical parser's case-insensitivity is inherited.
        assert_eq!(
            Field::Compaction.accepts("HEADROOM_AWARE"),
            Some("headroom_aware".to_string())
        );
    }

    /// **The trailing space survives the deep link.**
    ///
    /// `/settings prompt "❯ "` is the case that decides whether the port was
    /// real. `run` split on whitespace and trimmed, which would turn that
    /// template into `❯` — rendering flush against whatever the operator
    /// types — and nothing downstream would report the difference. The quoted
    /// parsing the `/prompt set` verb owned is carried, not reinvented.
    #[test]
    fn a_quoted_template_reaches_the_field_verbatim() {
        let _guard = settings_guard();
        newt_core::process_env::remove_var("NEWT_PROMPT");

        let out = run(&declining(), "prompt \"[$TIME] ❯ \"");
        assert_eq!(out.len(), 1, "{out:?}");
        assert_eq!(
            Field::Prompt.current(),
            "[$TIME] ❯ ",
            "the trailing space is the whole point of quoting it"
        );

        // Internal spaces too, and one layer of quotes only.
        run(&declining(), "prompt \"a  b\"");
        assert_eq!(Field::Prompt.current(), "a  b");
    }

    /// `reset` is a VALUE of the field, not a second verb — and it removes the
    /// variable rather than storing the word, so nothing is left for the next
    /// `/prompt` to explain.
    #[test]
    fn resetting_the_prompt_releases_it_to_config() {
        let _guard = settings_guard();
        newt_core::process_env::set_var("NEWT_PROMPT", "custom ");
        assert_eq!(Field::Prompt.current(), "custom ");

        run(&declining(), "prompt reset");
        assert!(
            std::env::var("NEWT_PROMPT").is_err(),
            "reset must remove the override, not store the word"
        );
        assert_ne!(Field::Prompt.current(), "reset");
    }

    /// A `Text` field is not a menu and not a number, and the hint says so.
    #[test]
    fn the_text_field_offers_a_release_and_a_shape_not_a_vocabulary() {
        assert_eq!(Field::Prompt.offered(), vec!["reset"]);
        let hint = Field::Prompt.accepts_hint();
        assert!(hint.contains("reset"), "{hint}");
        assert!(hint.contains("template"), "{hint}");
    }

    /// **The mode field's vocabulary IS the enum's** (#2009 PR4b).
    ///
    /// The styles, their order and their descriptions are read off
    /// `OperatingMode` rather than typed out beside it. A style added to the
    /// enum appears in the form without an edit here — which is the reuse the
    /// type's move down to core buys, beyond making the field possible at all.
    #[test]
    fn the_mode_fields_choices_are_the_enums_own() {
        use newt_core::operating_mode::OperatingMode;
        let offered = Field::Mode.offered();
        let want: Vec<&str> = OperatingMode::all().iter().map(|m| m.as_str()).collect();
        assert_eq!(offered, want, "the form drifted from the mode vocabulary");
        assert!(!want.is_empty(), "an empty list would make this vacuous");
        // Every style is choosable, `full-auto` included: this is the human's
        // door, and the human-only exclusion belongs to the MODEL's schema.
        assert!(offered.contains(&"full-auto"));
    }

    /// The verb and the field select one style, through one setter.
    #[test]
    fn the_mode_field_and_its_verb_resolve_to_one_state() {
        use newt_core::operating_mode::{session_operating_mode, OperatingMode};
        let _guard = settings_guard();
        newt_core::process_env::remove_var("NEWT_MODE");
        assert_eq!(session_operating_mode(), OperatingMode::Chat);
        assert_eq!(Field::Mode.current(), "chat");

        assert_eq!(
            apply(Field::Mode, "plan"),
            Ok("operating mode: plan".to_string())
        );
        assert_eq!(session_operating_mode(), OperatingMode::Plan);
        assert_eq!(Field::Mode.current(), "plan");
    }

    /// The keywords the verb accepted, kept by the absorption.
    #[test]
    fn the_mode_verbs_aliases_survive_absorption() {
        assert_eq!(Field::Mode.accepts("developer"), Some("dev".to_string()));
        assert_eq!(Field::Mode.accepts("sysadmin"), Some("admin".to_string()));
        assert_eq!(
            Field::Mode.accepts("FULL-AUTO"),
            Some("full-auto".to_string())
        );
        assert_eq!(Field::Mode.accepts("nonsense"), None);
    }

    /// **The verb and the field write the same state** (#2009 PR4).
    ///
    /// `/markdown off` set a `run_chat` local; `/settings markdown off` could
    /// not see it. Two writers for one setting is how they come to disagree,
    /// and it is why the receipt could not record a from→to. Both doors now
    /// go through `NEWT_MARKDOWN`, read back by the one resolver.
    /// `/settings prefix ctrl+a` persists to `[tui] prefix_key` (through the
    /// config seam — no real file) and takes effect this session; the
    /// resolver the panel driver parses reads it back; an unoffered chord is
    /// refused and writes nothing.
    #[test]
    fn the_prefix_field_persists_and_takes_effect_now() {
        let _guard = settings_guard();
        newt_core::process_env::remove_var("NEWT_PREFIX_KEY");
        let path = newt_core::Config::user_config_path().expect("a config path");
        assert_eq!(
            apply(Field::Prefix, "ctrl+a"),
            Ok("meta prefix key: ctrl+a".to_string())
        );
        let saved = config_fs::read(&path);
        assert!(
            saved.contains("[tui]") && saved.contains("prefix_key = \"ctrl+a\""),
            "{saved}"
        );
        assert_eq!(Field::Prefix.current(), "ctrl+a");
        assert_eq!(prefix_setting(), "ctrl+a");
        assert!(
            apply(Field::Prefix, "ctrl+q").is_err(),
            "not an offered chord"
        );
        assert_eq!(
            config_fs::read(&path),
            saved,
            "a refused value writes nothing"
        );
        newt_core::process_env::remove_var("NEWT_PREFIX_KEY");
    }

    #[test]
    fn the_markdown_field_and_its_verb_resolve_to_one_state() {
        let _guard = settings_guard();
        newt_core::process_env::remove_var("NEWT_MARKDOWN");
        assert_eq!(
            Field::Markdown.current(),
            crate::migration_notices::read(newt_core::config::session_markdown_mode).keyword(),
            "unpinned, the field reports what the resolver resolves"
        );

        assert_eq!(
            apply(Field::Markdown, "off"),
            Ok("markdown rendering: off".to_string())
        );
        assert_eq!(Field::Markdown.current(), "off");
        assert!(newt_core::config::markdown_is_session_pinned());

        // `auto` is a value, not a release: it means "follow colour", which
        // is a different state from `on` on a pipe.
        assert_eq!(
            apply(Field::Markdown, "auto"),
            Ok("markdown rendering: auto".to_string())
        );
        assert_eq!(Field::Markdown.current(), "auto");
        assert!(
            newt_core::config::markdown_is_session_pinned(),
            "`auto` is still an operator pin — it beats a config that says off"
        );
    }

    /// The keywords the verb accepted, kept. Absorbing a command must not
    /// silently drop an affordance operators already type.
    #[test]
    fn the_markdown_verbs_aliases_survive_absorption() {
        assert_eq!(Field::Markdown.accepts("always"), Some("on".to_string()));
        assert_eq!(Field::Markdown.accepts("never"), Some("off".to_string()));
        assert_eq!(Field::Markdown.accepts("AUTO"), Some("auto".to_string()));
        assert_eq!(Field::Markdown.accepts("sometimes"), None);
    }

    #[test]
    fn the_aliases_the_absorbed_verbs_took_still_resolve() {
        for (field, typed, want) in [
            (Field::EditMode, "vim", "vi"),
            (Field::Tenacity, "inherit", "auto"),
            (Field::Tenacity, "reset", "auto"),
            (Field::Initiative, "inherit", "auto"),
            (Field::Initiative, "reset", "auto"),
            (Field::Cognition, "none", "off"),
            (Field::Cognition, "reset", "auto"),
            (Field::Cognition, "persona", "auto"),
        ] {
            assert_eq!(
                field.accepts(typed).as_deref(),
                Some(want),
                "/{} {typed} stopped resolving",
                field.name()
            );
        }
        // Anti-vacuous: `accepts` is not "yes to everything".
        assert_eq!(Field::Tenacity.accepts("obsessive"), None);
        assert_eq!(Field::Initiative.accepts("relentless"), None);
        assert_eq!(Field::Cognition.accepts("hard"), None);
        assert_eq!(Field::Thinking.accepts("maybe"), None);
    }

    /// A refused value on a dial writes nothing — the same law slice 1 pinned
    /// for the editor, now that four more fields can be refused.
    #[test]
    fn a_refused_dial_value_changes_nothing() {
        let _g = settings_guard();
        apply(Field::Tenacity, "relentless").expect("a level applies");
        let err = apply(Field::Tenacity, "obsessive").expect_err("not a level");
        assert!(err.contains("relentless"), "{err}");
        assert_eq!(Field::Tenacity.current(), "relentless", "a refusal wrote");
        // A pre-split level is not a tenacity level any more.
        assert!(apply(Field::Tenacity, "insistent").is_err());
        assert_eq!(Field::Tenacity.current(), "relentless", "a refusal wrote");
    }

    /// **The receipt destination is read from the registry, not assumed.**
    ///
    /// This is the law that keeps the two files honest with each other: a
    /// field of `/settings` whose verb the registry has not given a
    /// destination writes nothing, and the ratchet keeps counting it. You
    /// cannot add a knob to this form and get provenance by accident.
    #[test]
    fn every_field_declares_where_its_receipt_lands() {
        use crate::slash_registry::{receipt_for, Receipt};
        for field in Field::ALL {
            assert_eq!(
                receipt_for(field.name()),
                Receipt::Journal,
                "/settings {} has no declared receipt destination",
                field.name()
            );
            assert!(change_for(field.name(), "a".into(), "b".into(), "/settings").is_some());
        }
        // **Anti-vacuous.** If the column read `Journal` for everything,
        // reading it would prove nothing. `/setup` mutates and records no
        // decision; `/help` mutates nothing.
        //
        // This used to name `/rounds`, which is the whole point of #1998: the
        // example had to be replaced because the debt it stood for was paid.
        // It then named `/remember`, and #2085 PR-E2 paid that one too — to the
        // OTHER destination. That makes it the sharpest row here: the loop
        // above demands `Journal` of every field, and `/remember` is `Event`,
        // so the two writers provably read disjoint variants rather than one
        // shared "somebody records this".
        assert_eq!(receipt_for("remember"), Receipt::Event);
        assert_eq!(receipt_for("setup"), Receipt::Missing);
        assert_eq!(receipt_for("help"), Receipt::None_);
        assert_eq!(receipt_for("zzznotacommand"), Receipt::Missing);
    }

    /// The recorded change carries the transition AND the route taken — the
    /// half of the event a reader cannot reconstruct from the resulting state.
    #[test]
    fn the_recorded_change_names_the_route_and_the_transition() {
        let change = change_for(Field::EditMode.name(), "vi".into(), "emacs".into(), "/vi")
            .expect("declared");
        assert_eq!(change.setting, "edit-mode");
        assert_eq!(change.from.to_string(), "vi");
        assert_eq!(change.to.to_string(), "emacs");
        assert_eq!(change.via, "/vi");
        assert_eq!(
            change.schema,
            newt_core::settings_receipt::SETTING_CHANGE_SCHEMA_V1
        );
    }

    /// **The round cap takes a number, which no other field does** (#1998).
    ///
    /// The form only knew closed vocabularies, and that — not the derived
    /// operations — is what actually kept `/rounds` outside it.
    #[test]
    fn the_round_cap_accepts_a_bounded_number_and_a_release_token() {
        let max = newt_core::tenacity::RELENTLESS_TOOL_ROUND_TARGET;
        assert_eq!(Field::Rounds.accepts("50").as_deref(), Some("50"));
        // Canonicalized, so `0050` and `50` are one value with one address.
        assert_eq!(Field::Rounds.accepts(" 0050 ").as_deref(), Some("50"));
        assert_eq!(
            Field::Rounds.accepts(&max.to_string()).as_deref(),
            Some(max.to_string().as_str())
        );
        // Every word the verb uses to RELEASE the override lands on one value.
        for release in ["auto", "reset", "default"] {
            assert_eq!(Field::Rounds.accepts(release).as_deref(), Some("auto"));
        }
        // Anti-vacuous: the bound is real at both ends, and it is a number
        // field, not a "take anything" field.
        assert_eq!(Field::Rounds.accepts("0"), None, "0 rounds is not a limit");
        assert_eq!(Field::Rounds.accepts(&(max + 1).to_string()), None);
        assert_eq!(
            Field::Rounds.accepts("unlimited"),
            None,
            "a verb affordance, not a value"
        );
        assert_eq!(Field::Rounds.accepts("banana"), None);
    }

    /// A numeric field is asked for, not chosen from — and it is still a typed
    /// definition, so it still renders everywhere the menus do.
    #[test]
    fn the_number_field_is_a_text_definition_not_a_menu() {
        let _g = settings_guard();
        let asked = value_menu(Field::Rounds);
        assert!(
            asked
                .controls
                .iter()
                .all(|c| !matches!(c.kind, newt_interaction::ControlKind::Choice { .. })),
            "a number has no menu to pick from"
        );
        let rendered = newt_core::markup::plain::render(&asked);
        assert!(rendered.contains("10000"), "the bound is shown: {rendered}");

        // …and the menus still are menus.
        assert!(value_menu(Field::Tenacity)
            .controls
            .iter()
            .any(|c| matches!(c.kind, newt_interaction::ControlKind::Choice { .. })));
    }

    /// **The form drives the numeric field end to end**: pick `rounds`, type a
    /// number, and the cap is set.
    #[test]
    fn the_form_walks_to_the_round_cap_and_takes_a_typed_number() {
        let _g = settings_guard();
        newt_core::tenacity::set_session_tool_rounds(None);
        let index = Field::ALL
            .iter()
            .position(|f| *f == Field::Rounds)
            .expect("rounds is offered")
            + 1;
        let out = run(
            &answering_owned(vec![index.to_string(), "320".to_string()]),
            "",
        );
        assert_eq!(out, vec!["tool-call round limit: 320".to_string()]);
        assert_eq!(newt_core::tenacity::session_tool_rounds(), Some(320));

        // An empty line backs out rather than being an invalid number.
        let out = run(
            &answering_owned(vec![index.to_string(), "  ".to_string()]),
            "",
        );
        assert_eq!(out, vec!["settings: cancelled".to_string()]);
        assert_eq!(
            newt_core::tenacity::session_tool_rounds(),
            Some(320),
            "backing out of the number must not clear the cap"
        );
    }

    /// **The receipt for a cap carries the whole derivation** (#1998) — the
    /// difference between "320 rounds" and the record #1965 asked for.
    #[test]
    fn the_round_cap_records_its_derivation_not_just_the_number() {
        use newt_core::settings_receipt::SettingValue;
        let _g = settings_guard();
        newt_core::tenacity::set_configured_tool_rounds(Some(40));
        newt_core::tenacity::set_cli_tenacity(newt_core::Tenacity::Relentless);
        newt_core::tenacity::set_session_tool_rounds(None);

        let from = Field::Rounds.value_now();
        apply(Field::Rounds, "320").expect("in range");
        let to = Field::Rounds.value_now();
        let change = change_for(Field::Rounds.name(), from, to, "/max-rounds").expect("declared");

        let SettingValue::ToolRounds(after) = &change.to else {
            panic!("the cap was recorded as a bare token: {:?}", change.to);
        };
        assert_eq!(after.rounds, 320);
        assert_eq!(after.configured, 40, "the baseline it escalated over");
        assert!(after.is_escalated());
        assert_eq!(change.via, "/max-rounds", "the alias typed is bound in");

        // Anti-vacuous: a token-valued field is still a token, so the branch
        // above is about `Rounds` and not about every field.
        let token = change_for(
            Field::EditMode.name(),
            Field::EditMode.value_now(),
            Field::EditMode.value_now(),
            "/vi",
        )
        .expect("declared");
        assert!(matches!(token.to, SettingValue::Token(_)));
    }

    /// **No baseline means no invented one.** With nothing installed the cap
    /// records as a token — honest — rather than claiming a `configured` it
    /// never saw.
    #[test]
    fn a_cap_with_no_installed_baseline_records_a_token_not_a_guess() {
        use newt_core::settings_receipt::SettingValue;
        let _g = settings_guard();
        newt_core::tenacity::set_configured_tool_rounds(None);
        newt_core::tenacity::set_session_tool_rounds(Some(320));
        assert!(
            matches!(Field::Rounds.value_now(), SettingValue::Token(ref t) if t == "320"),
            "with no baseline the cap must record as a token, not a guessed derivation"
        );

        // Anti-vacuous: install one and the SAME override records as a
        // derivation, so the assertion above is about the baseline and not
        // about `value_now` always returning a token.
        newt_core::tenacity::set_configured_tool_rounds(Some(40));
        assert!(matches!(
            Field::Rounds.value_now(),
            SettingValue::ToolRounds(_)
        ));
    }

    /// The recording route applies exactly what the bare mutation would.
    ///
    /// The guard holds the journal off, so this creates no filesystem state:
    /// what it proves is that `apply_and_record` still performs the change,
    /// not what the written line looks like — which
    /// `newt_core::settings_receipt`'s own tests own.
    #[test]
    fn recording_does_not_change_what_gets_applied() {
        let _g = settings_guard();
        let recorded = apply_and_record(Field::Tenacity, "relentless", "/settings")
            .expect("an offered value applies");
        assert_eq!(Field::Tenacity.current(), "relentless");
        apply(Field::Tenacity, "auto").expect("released");
        let bare = apply(Field::Tenacity, "relentless").expect("an offered value applies");
        assert_eq!(recorded, bare, "the recorder changed the outcome");
    }

    /// **Every dial position is a token the form would accept.**
    ///
    /// The load-bearing guard for the typed door. `apply_cognition` /
    /// `apply_tenacity` report the change using a token, and `change_for`
    /// records that token as the new value — so a dial position whose token
    /// the form does not offer would journal a value `/settings cognition`
    /// could never be given. The two vocabularies derive from the same
    /// `Cognition::all()` / `Tenacity::all()` labels; this is what keeps that
    /// true after someone adds a ladder position to one of them.
    // Guards the typed door, which the lean build has no panel to call.
    #[cfg(feature = "rich-tui")]
    #[test]
    fn every_dial_position_is_a_token_the_form_offers() {
        use newt_core::cognition::CognitionOverride;
        use newt_core::role_profile::Cognition;
        use newt_core::Tenacity;

        let mut cognition = vec![CognitionOverride::Unset, CognitionOverride::Off];
        cognition.extend(Cognition::all().iter().copied().map(CognitionOverride::Set));
        for choice in cognition {
            let token = cognition_token(choice);
            assert!(
                Field::Cognition.accepts(&token).is_some(),
                "cognition dial position {choice:?} renders {token:?}, which the form refuses"
            );
        }

        let mut tenacity: Vec<Option<Tenacity>> = vec![None];
        tenacity.extend(Tenacity::all().iter().copied().map(Some));
        for level in tenacity {
            let token = tenacity_token(level);
            assert!(
                Field::Tenacity.accepts(&token).is_some(),
                "tenacity dial position {level:?} renders {token:?}, which the form refuses"
            );
        }

        let mut initiative: Vec<Option<newt_core::Initiative>> = vec![None];
        initiative.extend(newt_core::Initiative::all().iter().copied().map(Some));
        for level in initiative {
            let token = initiative_token(level);
            assert!(
                Field::Initiative.accepts(&token).is_some(),
                "initiative dial position {level:?} renders {token:?}, which the form refuses"
            );
        }
    }

    /// **The receipt names the setting the door was asked to change, and the
    /// route the operator took.**
    ///
    /// The guard an adversarial review earned: with the `Field` handed to
    /// `recorded` unobserved, swapping `Field::Cognition` for
    /// `Field::Tenacity` inside `apply_cognition` left the runtime state
    /// right, the returned message right, and all 1289 tests green — while
    /// the journal gained a false `tenacity` row (from == to) and the
    /// operator's real cognition change was recorded nowhere. Exactly the
    /// #1965 gap this change closes, with a fabricated entry on top.
    ///
    /// Asserted through the DOOR, on the change the door produced. A test
    /// that called `change_for(Field::Cognition, ..)` beside it would supply
    /// the very field the door was supposed to choose, and could not catch
    /// the swap. Filesystem-free: `settings_guard` blanks the receipt path, so
    /// what is checked is the change that WOULD be written.
    ///
    /// **Grounded by `settings_form_pty_test`**, which drives the token door
    /// against a real `receipts.jsonl` and proves `record` actually appends.
    /// This test owns the half that one cannot vary — which setting and which
    /// route each door names — and that one owns the half this cannot see.
    #[cfg(feature = "rich-tui")]
    #[test]
    fn each_typed_door_journals_its_own_setting_and_route() {
        use newt_core::cognition::CognitionOverride;
        use newt_core::role_profile::Cognition;
        let _g = settings_guard();

        apply(Field::Cognition, "off").expect("arrange");
        let (_, change) =
            journalled_cognition(CognitionOverride::Set(Cognition::all()[0]), "/psyche edit");
        let change = change.expect("cognition declares a journal destination");
        assert_eq!(change.setting, "cognition", "the door journals ITS setting");
        assert_eq!(change.via, "/psyche edit", "the route is the one taken");
        assert_eq!(change.from.to_string(), "off");
        assert_eq!(change.to.to_string(), Cognition::all()[0].label());

        apply(Field::Tenacity, "normal").expect("arrange");
        let (_, change) = journalled_tenacity(None, "/psyche");
        let change = change.expect("tenacity declares a journal destination");
        assert_eq!(change.setting, "tenacity");
        assert_eq!(change.via, "/psyche");
        assert_eq!(change.from.to_string(), "normal");
        assert_eq!(change.to.to_string(), "auto", "None releases the override");

        apply(Field::Initiative, "patient").expect("arrange");
        let (_, change) = journalled_initiative(Some(newt_core::Initiative::Eager), "/psyche");
        let change = change.expect("initiative declares a journal destination");
        assert_eq!(
            change.setting, "initiative",
            "the door journals ITS setting"
        );
        assert_eq!(change.via, "/psyche");
        assert_eq!(change.from.to_string(), "patient");
        assert_eq!(change.to.to_string(), "eager");
    }

    /// **The two doors apply the same thing.**
    ///
    /// A typed caller and a token caller must be indistinguishable in what
    /// they leave behind, or the panel and the slash verb would drift into
    /// two settings wearing one name. Asserted on the runtime state AND on
    /// the reported message, since the message is what a receipt records.
    // Guards the typed door, which the lean build has no panel to call.
    #[cfg(feature = "rich-tui")]
    #[test]
    fn the_typed_door_and_the_token_door_agree() {
        use newt_core::cognition::CognitionOverride;
        use newt_core::role_profile::Cognition;
        use newt_core::Tenacity;
        let _g = settings_guard();

        // EVERY ladder position, not a sample: the panel offers all of them,
        // so a position the two doors disagree about is one an operator can
        // actually reach.
        let mut cognition = vec![
            (CognitionOverride::Unset, "auto".to_string()),
            (CognitionOverride::Off, "off".to_string()),
        ];
        cognition.extend(
            Cognition::all()
                .iter()
                .map(|c| (CognitionOverride::Set(*c), c.label().to_string())),
        );
        for (choice, token) in cognition {
            let token = token.as_str();
            // Start from somewhere else, so each door has something to change.
            apply(Field::Cognition, "off").expect("arrange");
            let typed = apply_cognition(choice, "/psyche");
            let after_typed = Field::Cognition.current();

            apply(Field::Cognition, "off").expect("arrange");
            let by_token =
                apply_and_record(Field::Cognition, token, "/settings").expect("offered token");
            assert_eq!(
                Field::Cognition.current(),
                after_typed,
                "same runtime state"
            );
            assert_eq!(typed, by_token, "same reported change");
        }

        let mut tenacity = vec![(None, "auto".to_string())];
        tenacity.extend(
            Tenacity::all()
                .iter()
                .map(|t| (Some(*t), t.label().to_string())),
        );
        for (level, token) in tenacity {
            let token = token.as_str();
            apply(Field::Tenacity, "normal").expect("arrange");
            let typed = apply_tenacity(level, "/psyche");
            let after_typed = Field::Tenacity.current();

            apply(Field::Tenacity, "normal").expect("arrange");
            let by_token =
                apply_and_record(Field::Tenacity, token, "/settings").expect("offered token");
            assert_eq!(Field::Tenacity.current(), after_typed, "same runtime state");
            assert_eq!(typed, by_token, "same reported change");
        }

        let mut initiative = vec![(None, "auto".to_string())];
        initiative.extend(
            newt_core::Initiative::all()
                .iter()
                .map(|i| (Some(*i), i.label().to_string())),
        );
        for (level, token) in initiative {
            let token = token.as_str();
            apply(Field::Initiative, "measured").expect("arrange");
            let typed = apply_initiative(level, "/psyche");
            let after_typed = Field::Initiative.current();

            apply(Field::Initiative, "measured").expect("arrange");
            let by_token =
                apply_and_record(Field::Initiative, token, "/settings").expect("offered token");
            assert_eq!(
                Field::Initiative.current(),
                after_typed,
                "same runtime state"
            );
            assert_eq!(typed, by_token, "same reported change");
        }
    }

    /// The deprecated verbs point at their new home and say they still work —
    /// never "unknown command" (#1981).
    #[test]
    fn a_deprecated_verb_names_its_replacement_without_retiring_itself() {
        let notice = moved_notice("vi", Field::EditMode);
        assert!(notice.contains("/vi still works"), "{notice}");
        assert!(notice.contains("/settings edit-mode"), "{notice}");
    }

    #[cfg(feature = "rich-tui")]
    #[test]
    fn personality_apply_records_typed_override_and_inherit_without_pinning_other_dials() {
        use newt_core::role_profile::{PersonalityLevel, PersonalityTraits};
        use newt_core::settings_receipt::SettingValue;
        let _g = newt_core::test_guard::GlobalSettingsGuard::acquire();
        let _ = newt_core::runtime::drain_preference_actions();
        let before_cognition = newt_core::cognition::cli_cognition();
        let before_tenacity = newt_core::tenacity::cli_tenacity();
        let before_initiative = newt_core::initiative::cli_initiative();
        let mut current = PersonalityTraits::default();
        let next = PersonalityTraits {
            warmth: Some(PersonalityLevel::try_from(0).unwrap()),
            ..Default::default()
        };
        let (_, receipt) = journalled_personality(&mut current, next, "/psyche edit");
        assert_eq!(current, next);
        let receipt = receipt.expect("psyche declares its journal destination");
        assert_eq!(receipt.setting, "psyche");
        assert_eq!(receipt.via, "/psyche edit");
        assert_eq!(
            receipt.from,
            SettingValue::from(PersonalityTraits::default())
        );
        assert_eq!(receipt.to, SettingValue::from(next));
        let (_, reset) =
            journalled_personality(&mut current, PersonalityTraits::default(), "/psyche");
        let reset = reset.unwrap();
        assert_eq!(reset.from, SettingValue::from(next));
        assert_eq!(reset.to, SettingValue::from(PersonalityTraits::default()));
        assert_eq!(current, PersonalityTraits::default());
        assert_eq!(newt_core::cognition::cli_cognition(), before_cognition);
        assert_eq!(newt_core::tenacity::cli_tenacity(), before_tenacity);
        assert_eq!(newt_core::initiative::cli_initiative(), before_initiative);
        assert!(newt_core::runtime::drain_preference_actions().is_empty());
    }
}