feat(core): score a category by how much is wrong, not whether anything is

.changeset/score-proportionality.md

@@ -0,0 +1,25 @@
+---
+'@svelte-vitals/core': minor
+'svelte-vitals': minor
+'@svelte-vitals/vite': minor
+---
+
+Category scores now reflect **how much** is wrong, not merely whether anything is.
+
+A key — a route or a source file — used to start at 100 and lose a fixed number of points per failing rule.
+That capped what a category could express: `architecture` is eight `info` rules, so no amount of bad code
+moved it below 92, and three more scopes bottomed out above 90. It also erased magnitude, because one
+finding moves a mean of N keys by `1/N`: on a large project, one finding and several hundred displayed the
+same score.
+
+A key now scores the share of what it was measured against that is intact, weighted by severity. Every
+category can reach 0, and the score moves with the number of findings.
+
+**Any category carrying a finding changes, most of them downward and by more than a point; a clean 100 stays 100.** `seo` and `correctness` stay within a point of their old values; `architecture`, `security` and
+`performance` move further, because their scales were the most compressed. A `--min-health` gate calibrated
+against the old numbers will start failing — recalibrate it against the new scale. `routes[].score` in the
+JSON report changes meaning the same way. Stored baselines are unaffected, since they key on findings rather
+than scores.
+
+Unchanged: the site-wide penalty stays in absolute points, a `critical` still caps a category at 79, and a
+displayed 100 still means no finding among the checks that ran.

docs/src/content/docs/guides/(reporting)/health-report.md

@@ -15,12 +15,10 @@ Health is computed in two stages:
 
 For each active category (SEO, Performance), svelte-vitals computes an independent score:
 
-- Every route starts at **100**.
-- Each failing finding deducts points based on severity:
-  - `critical` → −15 per route
-  - `warning` → −5 per route
-  - `info` → −1 per route
-- Deductions are taken once per (route, rule) pair — duplicates take the maximum deduction, not a sum.
+- Each route scores the share of that category's checks it was measured against — weighted by severity —
+  that passed: no failures scores **100**, every applicable check failing scores **0**.
+- Severity sets the weight a failing check carries: `critical` weighs 15, `warning` weighs 5, `info` weighs 1.
+- A failing check counts once per (route, rule) pair — duplicates take the maximum severity, not a sum.
 - Route scores are averaged to produce the category's headline score.
 - If any critical finding is present, the headline score is capped at **79**.
 

docs/src/content/docs/guides/(reporting)/reporters.md

@@ -53,7 +53,7 @@ svelte-vitals --reporter json
   "routes": [
     {
       "route": "/about", // a route id, or a source file path for file-scoped rules
-      "score": 95,
+      "score": 95, // share of this route's rule inventory (by category/scope, weighted by severity) left intact
       "issues": [
         {
           "id": "seo/single-h1", // the rule id

docs/src/content/docs/ja/guides/(reporting)/health-report.md

@@ -15,12 +15,10 @@ Health は 2 段階で計算されます：
 
 svelte-vitals は、アクティブなカテゴリ（SEO、パフォーマンスなど）ごとに独立したスコアを計算します：
 
-- すべてのルートは **100** から始まります。
-- 失敗した検出結果はそれぞれ、重大度に応じてポイントを差し引きます：
-  - `critical` → ルートごとに −15
-  - `warning` → ルートごとに −5
-  - `info` → ルートごとに −1
-- 差し引きは（ルート、ルール）ペアごとに一度だけです。同じペアで重複した場合は、合計せず最大の差し引きだけを適用します。
+- 各ルートは、そのカテゴリで測定対象となったチェックのうち、重大度で重み付けした上で合格した割合をスコアとします。
+  失敗が一つも無ければ **100**、該当するチェックがすべて失敗すれば **0** になります。
+- 失敗したチェックの重みは重大度が決めます：`critical` は 15、`warning` は 5、`info` は 1 です。
+- 失敗したチェックは（ルート、ルール）ペアごとに一度だけ数えます。同じペアで重複した場合は、合計せず最大の重大度を適用します。
 - ルートスコアを平均してカテゴリの見出しスコアを算出します。
 - クリティカルな検出結果が存在する場合、見出しスコアは **79** にキャップされます。
 

docs/src/content/docs/ja/guides/(reporting)/reporters.md

@@ -53,7 +53,7 @@ svelte-vitals --reporter json
   "routes": [
     {
       "route": "/about", // ルート ID。ファイル単位のルールではソースファイルのパス
-      "score": 95,
+      "score": 95, // このルートが属するカテゴリ/スコープのルール一覧（重大度で重み付け）のうち、無傷で残った割合
       "issues": [
         {
           "id": "seo/single-h1", // ルール ID