feat(optimize): add --subtract, the subtraction axis, behind a deterministic floor

Every command so far asked an addition question — what to add, what to move,
what it costs. Nothing asked what is no longer earning its always-loaded rent.
This adds that axis as a fourth lensCheck on the existing hybrid motor rather
than a new scanner or a 22nd command: the measured payoff (~18% of one file)
justifies a mode, not machinery.

It is the only lens that proposes REMOVING config, so it carries a guarantee
the others don't need: a load-bearing block is never a candidate. Precision is
asymmetric — a missed dead line costs a few tokens per turn, a deleted one
costs a wrong remote or a broken script — so the floor is decided in code
(lib/floor-exclusion.mjs) before the opus judge sees anything, never in prose.

Granularity is the leaf block, with two structural exceptions: a paragraph
ending in ':' merges with the list it introduces, and an ordered list is a
contract whose steps inherit floor from any sibling. Unordered lists
deliberately do not inherit — a load-bearing bullet and a disposable one
routinely share a list, and container-reasoning is the error the hand-built
ground truth exists to catch.

Verified against that ground truth (built before any classifier existed), with
the comparison machine-checked rather than read by eye: zero load-bearing
blocks proposed, 11/18 deletable groups surfaced, ~756 tok ~ 18% of a ~4300
token file — inside the pre-registered band. The first run found five floor
violations the synthesized fixture missed; each got a structural rule and a
fixture shape so it cannot regress.

Three real bugs the dogfood run exposed, all now covered:
- JS \b is ASCII-only, so /\bunngå\b/ never matches — every Norwegian keyword
  ending in æ/ø/å was silently dead.
- A bare word/word is not a path; "pros/cons" vetoed the largest deletable
  block until PATH_RE was tightened to rooted paths and globs.
- "Mid-sentence" must key on a preceding lowercase letter; the loose version
  read **bold labels:** and quoted openers as entities, costing 4 of 11 groups.

BP-SUB-001 is grounded entirely in the Anthropic steering blog already cited by
BP-MECH-001..004 and asserts nothing from the talk that motivated the feature —
no "80%", no ablation figure.

Suite 1365 -> 1382/0. Frozen v5.0.0 snapshots untouched; plain optimize output
byte-identical on identical input (--subtract adds keys only when passed).
knowledge-refresh-cli's reference date moved to 2026-08-01: its premise that
every seed entry was verified 2026-06-20 expired when BP-SUB-001 got a genuine
verification date, and backdating the entry to fit the test would have been a
lie about when its source was checked.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RW2haJXbxZpKivKHseSXNh
This commit is contained in:
Kjell Tore Guttormsen 2026-07-31 16:24:51 +02:00
commit e9921d3c9d
13 changed files with 1080 additions and 32 deletions

View file

@ -24,6 +24,7 @@ is hybrid: a cheap deterministic pre-filter finds candidates, then the opus
- **Lifecycle phrasing → hooks** (BP-MECH-001)
- **Unscoped path-specific instructions → path-scoped rules** (BP-MECH-002)
- **Absolute "never" prohibitions → permissions / hooks** (BP-MECH-004)
- **`--subtract`:** instructions that no longer earn their always-loaded rent (BP-SUB-001)
Each finding cites its register rule + source URL. A clean CLAUDE.md returns "no
opportunities" — that is a good result, not a failure.
@ -34,7 +35,21 @@ opportunities" — that is a good result, not a failure.
Split `$ARGUMENTS` into a path (first non-flag argument; default: current working
directory) and flags. Recognized flags: `--global` (include the user `~/.claude`
cascade in discovery).
cascade in discovery) and `--subtract` (add the subtraction axis, below).
**`--subtract` — the inverse question.** Every other lens asks what to *add* or
*move*; this one asks what no longer earns its always-loaded rent. It is opt-in
because it asks something different, and because deleting is not undoable by
reading. Pair it with `--global` to reach the user-level CLAUDE.md, where the
always-loaded cost actually sits (it loads in every repo, every session).
If `--subtract` is present, say so up front:
```
Also running the subtraction axis — instructions that cost tokens every turn
without telling me anything I couldn't work out. Load-bearing local facts
(remotes, versions, paths, policy) are excluded before anything is judged.
```
Tell the user:
@ -52,7 +67,9 @@ Generate a session ID (`YYYYMMDD_HHmmss`) if no active session exists.
mkdir -p ~/.claude/config-audit/sessions/{session-id} 2>/dev/null
GLOBAL_FLAG=""
if echo "$ARGUMENTS" | grep -q -- "--global"; then GLOBAL_FLAG="--global"; fi
node ${CLAUDE_PLUGIN_ROOT}/scanners/optimize-lens-cli.mjs <target-path> --output-file ~/.claude/config-audit/sessions/{session-id}/optimize-lens.json $GLOBAL_FLAG 2>/dev/null; echo $?
SUBTRACT_FLAG=""
if echo "$ARGUMENTS" | grep -q -- "--subtract"; then SUBTRACT_FLAG="--subtract"; fi
node ${CLAUDE_PLUGIN_ROOT}/scanners/optimize-lens-cli.mjs <target-path> --output-file ~/.claude/config-audit/sessions/{session-id}/optimize-lens.json $GLOBAL_FLAG $SUBTRACT_FLAG 2>/dev/null; echo $?
```
Exit code 0 is normal. Only exit code 3 is a real error → "The lens couldn't run.
@ -64,8 +81,13 @@ Read `~/.claude/config-audit/sessions/{session-id}/optimize-lens.json` with the
Read tool. It has `deterministic` (already-confirmed OPT findings), `candidates`
(pre-filter candidates with register provenance), `register`, and `counts`.
**Early exit:** if `counts.deterministic === 0` and `counts.candidates === 0`,
skip the agent and tell the user plainly:
Under `--subtract` it also has a `subtract` block (`candidates`, `register`) and
`counts.subtractCandidates`. Each subtraction candidate spans `line``endLine`
(a whole block). Include the whole `subtract` block when spawning the agent.
**Early exit:** if `counts.deterministic === 0` and `counts.candidates === 0`
(and, under `--subtract`, `counts.subtractCandidates === 0`), skip the agent and
tell the user plainly:
```
✓ No mechanism-fit opportunities found.
@ -117,6 +139,11 @@ End with context-sensitive next steps, explaining WHY each is useful:
- This command is **agent-driven and not byte-stable** — its output is a
human-facing report, deliberately outside the deterministic snapshot suite.
- `--subtract` **proposes, never writes.** Nothing is deleted; act on a finding
via `/config-audit plan``/config-audit implement` (backup + rollback).
- The subtraction floor is deterministic and runs *before* the agent, so a
load-bearing block is never a candidate. It errs toward keeping: on a
well-maintained config this axis is mostly a no-op, and that is a good result.
- The deterministic half (CA-OPT-001) also rides in the normal orchestrated
audit; this command adds the prose-judgment half on top.
- No files are modified. To act on a finding, use `/config-audit plan`