feat(model-router): wave 4-B — prompt classifier

Plain composer prompts with no route in force get a turn-scoped effort
from $.model.classify (design/analysis/coding/bookkeeping/chat → phase
effort, effort only, never the model). Bounded by a 3 s clock race, a
user interrupt neither counts nor writes, three failures in a row pause
it for cooldownMinutes (one toast, status marker, cleared by /route
reload). No dialog, no routing.json write on a classified route. New
Config key `classify` (default on, pickSwitch), `/route classify on|off`
session toggle, `/route show` line and argumentHint. An explicit user
/effort beats the guess (engineBase check).

Docs: README classifier paragraph, USAGE row + sentence, CHANGELOG,
effort-shift.md. Kit suite 428 tests.

README.md

@@ -135,12 +135,13 @@ effort, never version. Transcript audit `python3 lib/effort-audit.py`.
 - Main loop: every request gets the route in force. A typed skill with a row routes the main loop to it; a best-tier row (`plan`, `reflect`, `orchestrate`, `escalate`) holds across turns in a run slot until `/route clear`, `/route off`, a user `/model` or a typed skill on a non-best row. A skill without a row leaves the route as it is.
 - Sub-agents: a routed agent gets its row's model at spawn, within its tier and only upward from its frontmatter model, and the row's effort on every step. Explicit `model` / `effort` params on the Agent call win; a project-defined agent of the same name keeps its own definition. Built-ins: Explore runs on sonnet/medium, Plan on opus/xhigh.
 - Levers inside a run: `ultrathink` in a prompt sets the turn's minimum effort; `/route effort=max` holds until `/route clear`. The built-in `/effort` is not a lever inside a run, rows and routes outrank it.
-- `/route` (user command) shows or sets the route: `show`, `clear`, `off`, `on`, `reload`, `pending` (rows and phases not confirmed yet), `ask on|off` (first-use dialog on or off), `forget <name|all|projects>` (takes decisions back: a changed row returns to its shipped phase; `all` and `projects` ask first), a phase name, `model=<alias|id> effort=<level>`, `switch on|off`, `verbose on|off` (logs transitions only: each change of model or effort, with a few words of cause). `/route show` names the run slot when one holds (`main: run <phase>`). The model sets routes through a `route` tool.
+- Prompt classifier: a plain prompt typed in the composer (12 characters or more, not a slash command) that no keyword rule, skill, run slot, `/route` or floor covers is sent to the engine's small fast model, one call, bounded to 3 seconds (the prompt waits for it, typically under a second). The label (`design`, `analysis`, `coding`, `bookkeeping`, `chat`) maps to plan, reflect, implement or apply (`chat` routes nothing), and that phase's effort becomes the turn's default. Effort only: the main model never moves because of a guess, no dialog opens and no file is written. The route is gone at the end of the turn, a later route call or typed skill replaces it, and a `/effort` you set yourself beats it. A typed best-tier skill holds its run slot across turns, so nothing is classified there until `/route clear`. Long prompts are sampled (first 500 and last 1500 code points), so pasted text at the end can steer one turn's effort. Three failures in a row pause it for `cooldownMinutes` (one toast, `classifier: paused` in the status line). Never in a sub-agent, mid-turn or under `-p`. Off per session with `/route classify off`, per machine with `"classify": false`. The status line reads `route: classifier <phase>`; `/route verbose on` adds the transition line.
+- `/route` (user command) shows or sets the route: `show`, `clear`, `off`, `on`, `reload`, `pending` (rows and phases not confirmed yet), `ask on|off` (first-use dialog on or off), `forget <name|all|projects>` (takes decisions back: a changed row returns to its shipped phase; `all` and `projects` ask first), a phase name, `model=<alias|id> effort=<level>`, `switch on|off`, `classify on|off` (the prompt classifier, below), `verbose on|off` (logs transitions only: each change of model or effort, with a few words of cause). `/route show` names the run slot when one holds (`main: run <phase>`). The model sets routes through a `route` tool.
 - First use: the first time a rowed skill is typed, a rowed agent is spawned or a phase is declared on the main loop through the `route` tool, the mod asks once whether the route is right. The question gives context: the skill's description (first sentence of its `SKILL.md` frontmatter) or the agent's, the phase with its `about` line, and the model id and effort the next step really runs on; a declared phase also says what uses it (rows, prompt rules). A row offers Later, Keep or Change; a declared phase offers Later or Keep. Change asks the model (fable, opus, sonnet, haiku, each shown with the tier it heads), then the effort among those the phases on that model use (shipped table: fable medium, high, xhigh or max; sonnet low, medium, high or xhigh; opus and haiku have one level each, so no question), then Everywhere or This project only. Rows stay phase names, so the pair maps to an existing phase: the row's current phase wins a tie and the same phase counts as Keep; a pair no phase offers needs a new phase added by hand in routing.json. Everywhere moves the row and records the shipped phase under `changed`; This project only stores an exception under `projects`, keyed by the origin remote reduced to `host/path` (no credentials, no local paths; a remote that cannot be read that way offers no project choice). Keep lands under `confirmed`; Later, a dismissed dialog or a free-text answer asks again next session. After a skill row changes, a toast names the model and effort that skill now runs on, plus the `/route switch on` hint when the main loop holds back a downgrade. One dialog at a time, never in a headless (`-p`) run, never inside a sub-agent.
 - Only a dialog answer, `/route ask on|off` or `/route forget` writes `routing.json`, never the model. Writes are serialized, capped at 64 KiB, and refused when the file is missing (it is never created). Each write leaves the config repo dirty; a toast reminds you to commit it from there.
 - The spinner suffix and the status line under the prompt show the route in force.
 
-Config layers: `mods/model-router/routing.json` (tracked: phases with their tier, effort and `about` line, rows, decisions, `ask`), then the optional per-machine `~/.claude/model-router.json`, which wins. A `.claude/model-router.json` inside a project is never read. Machine keys: `models` (alias → full id), `windows` (context window per full id), `tiers` (ordered alias lists per tier: `best` fable>opus>sonnet, `big` opus>fable>sonnet, `work` sonnet>opus, `cheap` haiku>sonnet; the first alias not down is used), `fallback` (the rank order of the aliases, best first, used by the breaker), `cooldownMinutes` (how long a model stays marked down after an availability error, 15 by default, doubling per episode up to 300), `mainUpgrade` (default `true`: the main loop may move up to a phase's tier), `upgradeMaxTokens` (default 200000: no main-loop upgrade above this context size, since an upgrade re-reads the whole context cold), `phases`, `agents`, `skills`, `prompt` (rules), `mainModelSwitch` (default `false`), `verbose` (default `false`; `true` logs transitions only, a non-boolean value falls back to `false`), `spinner` (default `true`), `enabled` (default `true`; `false` turns the mod off on that machine), `ask` (overrides routing.json's `ask` on that machine). A `null` value in `agents` or `skills` drops a row. Edit phases and rows by hand in routing.json (a phase's `about`, 120 characters at most, is read from there only and shown in the dialog; a model and effort pair no phase offers needs a new phase there); without it the mod runs the code's default phases, with no rows and no dialog. `/route reload` re-reads both files.
+Config layers: `mods/model-router/routing.json` (tracked: phases with their tier, effort and `about` line, rows, decisions, `ask`), then the optional per-machine `~/.claude/model-router.json`, which wins. A `.claude/model-router.json` inside a project is never read. Machine keys: `models` (alias → full id), `windows` (context window per full id), `tiers` (ordered alias lists per tier: `best` fable>opus>sonnet, `big` opus>fable>sonnet, `work` sonnet>opus, `cheap` haiku>sonnet; the first alias not down is used), `fallback` (the rank order of the aliases, best first, used by the breaker), `cooldownMinutes` (how long a model stays marked down after an availability error, 15 by default, doubling per episode up to 300), `mainUpgrade` (default `true`: the main loop may move up to a phase's tier), `upgradeMaxTokens` (default 200000: no main-loop upgrade above this context size, since an upgrade re-reads the whole context cold), `phases`, `agents`, `skills`, `prompt` (rules), `mainModelSwitch` (default `false`), `classify` (default `true`; `false` stops the prompt classifier on that machine), `verbose` (default `false`; `true` logs transitions only, a non-boolean value falls back to `false`), `spinner` (default `true`), `enabled` (default `true`; `false` turns the mod off on that machine), `ask` (overrides routing.json's `ask` on that machine). A `null` value in `agents` or `skills` drops a row. Edit phases and rows by hand in routing.json (a phase's `about`, 120 characters at most, is read from there only and shown in the dialog; a model and effort pair no phase offers needs a new phase there); without it the mod runs the code's default phases, with no rows and no dialog. `/route reload` re-reads both files.
 
 Limits: the main loop changes model only with `mainModelSwitch` on, and each switch into another model costs one cold-cache step. The hooks send full model ids, so the `models` table has to follow new model versions.
 
@@ -234,7 +235,7 @@ a different package, ships its own conflicting `graphify` bin) — see
 | `/profile` | Activate a skill profile (web / seo / web-full / full / max / backend / design / dev / qa / audit / minimal) (default: full) |
 | `/tour` | Grouped all-axes sweep — cleanup + security + reconcile + doc, fix and loop until clean |
 | `/site-motion` | Site-level motion: scroll engine choice, page transitions, pin/scrub sequencing across a page or Astro route (design stack) |
-| `/route` | model-router mod: show or set the main-loop route (show, clear, off, on, reload, pending, ask on\|off, <phase>, model=… effort=…, switch on\|off, verbose on\|off: transitions only) |
+| `/route` | model-router mod: show or set the main-loop route (show, clear, off, on, reload, pending, ask on\|off, <phase>, model=… effort=…, switch on\|off, classify on\|off, verbose on\|off: transitions only) |
 
 > This table lists personal skills. Gstack skills (investigate, review, retro,
 > office-hours, cso…) and marketplace plugins add many more — run