docs(index): add dream + experiment-spec rows, and gate the index

Both skills shipped without an index row. The rows existed — on the feature
branches deleted in #22 — and were dropped by the squash-merge that followed
a directory reorg: the SKILL.md landed under skills/, the row did not. Nothing
errored, the index just under-reported the library to every harness reading it.

Adding two rows by hand fixes today and not tomorrow, so the assertion goes in
`task check` via bin/check-index, following the same pattern as
bin/should-skip-release: a real script with a real test, not untested logic
buried in a Taskfile. It checks both directions — a skill with no row, and a
row naming a skill that no longer exists.

Verified by mutation: deleting the `dream` row turns `task check` red and the
report names it.

Closes #15
Bump-Type: patch

SKILLS_INDEX.md

@@ -19,9 +19,11 @@ This index lists all available engineering skills. Load the full SKILL.md on dem
 | `gitea-ci` | Gitea CI/CD pipeline with act_runner, buildah, k3s, GitHub mirror | Setting up or debugging CI on this infra |
 | `debug` | Hypothesis-first debugging discipline | Any test failure or bug whose cause is not immediately obvious |
 | `feature-spec` | Implementation-level feature spec (tighter than spec-driven-dev) | Scoping one feature inside an already-specced project |
+| `experiment-spec` | Rigorous experiment spec — falsifiable hypothesis, quantitative acceptance, null-result protocol | Scoping a research/ML phase instead of a feature |
 | `playwright` | Playwright E2E testing — setup, HTMX patterns, SSE streams, CI wiring | Adding browser tests to any project with a web UI |
 | `session-retrospective` | Surface non-obvious learnings from a session log | After a coding session ends, before context is lost |
 | `trainer` | Two-phase brain curation (score candidates, write past quality gate) | Periodic brain pruning and curation |
+| `dream` | Reflective consolidation pass over an agent's memory directory | Pruning/merging memory files, rebuilding a memory index |
 | `grill-me` | Structured plan interrogation — Quick Poke, Full Grill, Pre-mortem | Stress-testing a plan before committing; end of Diamond 1; before promoting to pre-prod |
 | `own-the-task` | Delegation ownership — Intake → Brief → Plan → Execute | A task is handed over open-ended; "take this off my plate"; before a plan exists |
 | `telos-load` | Load TELOS intention substrate at session start | Starting any koala session; before architectural decisions; CAD pipeline entry |

Taskfile.yml

@@ -94,7 +94,12 @@ tasks:
           count=$((count + 1))
         done
 
-        # 3. Plugin manifest version must match the latest tag, or installers
+        # 3. SKILLS_INDEX.md lists exactly the skills that exist. Delegated
+        #    to bin/check-index so the rule is covered by
+        #    tests/check_index_test.sh rather than living untested here.
+        sh '{{.TASKFILE_DIR}}/bin/check-index' '{{.TASKFILE_DIR}}' || fail=1
+
+        # 4. Plugin manifest version must match the latest tag, or installers
         #    never see the update (Claude Code gates updates on this field).
         if [ -f '{{.PLUGIN_MANIFEST}}' ]; then
           manifest_v=$(sed -n 's/.*"version"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' '{{.PLUGIN_MANIFEST}}' | head -1)

bin/check-index

@@ -0,0 +1,42 @@
+#!/bin/sh
+# check-index — asserts SKILLS_INDEX.md lists exactly the skills that exist.
+#
+# The index is hand-maintained and drifts silently in both directions: a skill
+# ships with no row (`dream` and `experiment-spec` did — their rows lived on
+# branches squash-merged after a directory reorg, so the SKILL.md landed and
+# the row did not, #15), or a row outlives the skill it names. Neither errors
+# anywhere; the library just misreports itself to every harness that reads it.
+#
+# Usage: check-index [checkout-root]   (defaults to this script's repo root)
+
+set -u
+
+ROOT=${1:-$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)}
+INDEX="$ROOT/SKILLS_INDEX.md"
+fail=0
+
+if [ ! -f "$INDEX" ]; then
+  echo "ERROR: missing SKILLS_INDEX.md" >&2
+  exit 1
+fi
+
+# A row is a table line whose first cell is the skill name in backticks.
+listed=$(sed -n 's/^|[[:space:]]*`\([^`]*\)`.*/\1/p' "$INDEX" | sort -u)
+
+for dir in "$ROOT"/skills/*/; do
+  name=$(basename "$dir")
+  [ -f "$dir/SKILL.md" ] || continue
+  printf '%s\n' "$listed" | grep -qx "$name" || {
+    echo "ERROR: skills/$name has no row in SKILLS_INDEX.md" >&2
+    fail=1
+  }
+done
+
+for name in $listed; do
+  [ -f "$ROOT/skills/$name/SKILL.md" ] || {
+    echo "ERROR: SKILLS_INDEX.md lists '$name', which has no skills/$name/SKILL.md" >&2
+    fail=1
+  }
+done
+
+exit $fail

tests/check_index_test.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+# Tests for bin/check-index.
+#
+# The regression these exist for: SKILLS_INDEX.md is maintained by hand, and
+# two skills (`dream`, `experiment-spec`) shipped without a row — the index
+# rows lived on feature branches that were squash-merged after a directory
+# reorg, so the SKILL.md landed and the row did not (#15, #22). Nothing
+# errored; the index just quietly under-reported the library.
+
+set -u
+
+ROOT=$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)
+SUT="$ROOT/bin/check-index"
+
+pass=0
+fail=0
+WORK=${TMPDIR:-/tmp}/check_index_test.$$
+
+if [ ! -f "$SUT" ]; then
+  printf 'FAIL: %s does not exist\n' "$SUT"
+  exit 1
+fi
+
+cleanup() { rm -rf "$WORK"; }
+trap cleanup EXIT INT TERM
+
+# new_fixture <name> — a checkout with skills/alpha and skills/beta.
+new_fixture() {
+  _f="$WORK/$1"
+  mkdir -p "$_f/skills/alpha" "$_f/skills/beta"
+  printf -- '---\nname: alpha\ndescription: a\n---\n' > "$_f/skills/alpha/SKILL.md"
+  printf -- '---\nname: beta\ndescription: b\n---\n' > "$_f/skills/beta/SKILL.md"
+  printf '%s' "$_f"
+}
+
+index() {
+  _dir=$1; shift
+  printf '# Engineering Skills Index\n\n| Skill | Description | Use when |\n|---|---|---|\n' > "$_dir/SKILLS_INDEX.md"
+  for _n in "$@"; do
+    printf '| `%s` | desc | when |\n' "$_n" >> "$_dir/SKILLS_INDEX.md"
+  done
+}
+
+# expect <0|1> <label> <fixture> [grep-for]
+expect() {
+  _want=$1; _label=$2; _fx=$3; _needle=${4:-}
+  _out=$(sh "$SUT" "$_fx" 2>&1); _rc=$?
+  if [ "$_rc" -ne "$_want" ]; then
+    fail=$((fail + 1)); printf '  FAIL %s (want rc=%s got %s)\n%s\n' "$_label" "$_want" "$_rc" "$_out"; return
+  fi
+  if [ -n "$_needle" ] && ! printf '%s' "$_out" | grep -q "$_needle"; then
+    fail=$((fail + 1)); printf '  FAIL %s (rc ok, but report never names %s)\n%s\n' "$_label" "$_needle" "$_out"; return
+  fi
+  pass=$((pass + 1)); printf '  ok   %s\n' "$_label"
+}
+
+fx=$(new_fixture complete); index "$fx" alpha beta
+expect 0 'every skill has a row' "$fx"
+
+fx=$(new_fixture missing); index "$fx" alpha
+expect 1 'a skill with no row is reported' "$fx" beta
+
+fx=$(new_fixture stale); index "$fx" alpha beta gamma
+expect 1 'a row for a skill that does not exist is reported' "$fx" gamma
+
+fx=$(new_fixture noindex)
+expect 1 'a missing index is reported' "$fx" SKILLS_INDEX.md
+
+printf '\ncheck_index: %d passed, %d failed\n' "$pass" "$fail"
+[ "$fail" -eq 0 ]