feat(effort): five shifter skills, lib/effort-shift.md, model-gate second axis

lib/effort-shift.md

@@ -0,0 +1,57 @@
+# Effort shift — phase-level reasoning effort on the main loop (BDR-NEXT)
+
+Shared include, companion of `lib/model-gate.md`: the gate fixes WHICH model
+reflects, this include fixes HOW HARD each phase thinks. The rungs are the
+user's: low (fix a line, run a script) · medium (day-to-day) · high
+(refactor, resisting bug) · xhigh (architecture, audit before validation) ·
+max (stuck error, judged need).
+
+## Mechanics (verified on Claude Code 2.1.283)
+
+- A skill's `effort:` frontmatter applies from the moment it loads to the
+  end of the turn: on the user's `/skill` and on a `Skill(...)` call by
+  Claude in an interactive session. Last loaded wins, both directions. The
+  prompt cache survives a shift.
+- Dispatched agents run on their own `effort:` pin, never on a shift.
+  Unpinned agents inherit the level in force at dispatch.
+- Headless sessions (`-p`, `claude agents`, SDK) ignore skill-level effort:
+  the run stays at the session level. `CLAUDE_CODE_EFFORT_LEVEL` beats every
+  frontmatter; keep it unset (the session banner warns).
+
+## Shifters
+
+`Skill(effort-low)` · `Skill(effort-medium)` · `Skill(effort-high)` ·
+`Skill(effort-xhigh)` · `Skill(effort-max)`. One tool call, one-line body.
+Typed by the user, `/effort-max` is a turn-scoped max: the relaunch lever
+after a STOP. `ultrathink` only adds an in-context nudge; the API level
+does not move.
+
+## Wiring — per orchestrator
+
+1. A dispatch span starts (executor, collector, fan-out) →
+   `Skill(effort-medium)`.
+2. Reflection resumes after a dispatch span (challenge synthesis, verdict,
+   plan revision) → `Skill(effort-<the skill's own level>)`. Concretely:
+   the line before every `lib/challenge-plan.md` call.
+3. The bookkeeping tail (memory commit, doc commit) → `Skill(effort-low)`.
+4. Escalation → `Skill(effort-max)`, then the skill's own level again once
+   the diagnosis is produced. Automatic points: verify-secure loop caps
+   (GATE 0 floor, GATE 1 conformity, GATE 2 security) and ship-feature
+   STEP 4b. Not automatic, by doctrine: the challenge fail-safe (a mute
+   challenger is an infrastructure failure) and "gone WRONG → STOP" (STOP
+   precedes any further reasoning); their STOP text names the level
+   reached and suggests `/effort-max` for the relaunch.
+
+## Re-assert
+
+- After any nested `Skill(...)` whose frontmatter carries a different
+  effort (feat → commit-change), reload the orchestrator's own level.
+- After a prose gate that ends the turn, the resumed turn runs at the
+  session level. If the resumed phase is reflection, its first step is
+  `Skill(effort-<own level>)`; dispatch and orchestration phases need
+  nothing.
+
+## Never
+
+- A shift never inside a dispatched agent: pins rule there.
+- Max is for diagnosis, not for retrying the same fix harder.

lib/model-gate.md

@@ -45,3 +45,7 @@ site — `model: "fable"` when the child performs reflection/orchestration on
 the main loop's behalf (skill-runners), otherwise its complexity tier
 (opus = dispatched judgment, sonnet = execution/collection, haiku = short
 mechanical probes).
+
+Effort is the second axis of the same table (BDR-NEXT): every typed agent
+carries an `effort:` pin next to `model:`, and the main loop shifts per phase
+through `lib/effort-shift.md`. Nothing dispatched inherits either axis.

lib/tests/effort-routing.test.sh

@@ -56,6 +56,13 @@ for s in brainstorming writing-plans; do
 done
 has "install-plugins.sh" 'effort: xhigh'
 
+# ── 5) shifter skills + include (spec D4)
+for l in low medium high xhigh max; do fm_has_effort "skills/effort-$l/SKILL.md" "$l"; has "skills/effort-$l/SKILL.md" "name: effort-$l"; done
+has "lib/effort-shift.md" 'Headless sessions'
+has "lib/effort-shift.md" 'Skill(effort-max)'
+has "lib/effort-shift.md" 'never inside a dispatched agent'
+has "lib/model-gate.md" 'lib/effort-shift.md'
+
 # ── summary (later tasks insert their locks ABOVE this line)
 printf 'effort-routing census: %d pass, %d fail\n' "$pass" "$fail"
 [ "$fail" -eq 0 ]