diff --git a/CLAUDE.md b/CLAUDE.md
index ced80711a..fefd383cd 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -226,6 +226,16 @@ conversation. The failure message carries the re-measure + ratchet protocol.
 tree (always-on vs per-invocation, `--diff`, `--budget`; `--exact` opts into the
 real tokenizer and POSTs file text to api.anthropic.com with an egress receipt).
 
+A third enforced ceiling is the context-budget ratchet:
+`test/context-budget-ratchet.test.ts` (free, runs in `bun run test`) grades the
+two ledgers the other guards don't cover — the always-on FULL-frontmatter
+aggregate and each skill's per-invocation eager tokens (SKILL.md + forced-read
+references) — against `test/fixtures/context-budget.json`. A skill that grows
+past its ceiling fails; a new skill fails until it's consciously budgeted. For
+legitimate growth or a landed reduction, re-run
+`bun test/helpers/capture-context-budget.ts` and commit the refreshed fixture
+in the same commit, so ceilings ratchet down and every win is locked.
+
 **Merge conflicts on SKILL.md files:** NEVER resolve conflicts on generated SKILL.md
 files by accepting either side. Instead: (1) resolve conflicts on the `.tmpl` templates
 and `scripts/gen-skill-docs.ts` (the sources of truth), (2) run `bun run gen:skill-docs`
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 77e188ae8..1dad1c54e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -174,6 +174,7 @@ eval files, and misses the strict classifier. No API keys needed.
 - **Generator tests** (`test/gen-skill-docs.test.ts`) — Tests the template system: verifies placeholders resolve correctly, output includes value hints for flags (e.g. `-d <N>` not just `-d`), enriched descriptions for key commands (e.g. `is` lists valid states, `press` lists key examples).
 - **Tier-alignment invariant** (`test/e2e-tier-alignment.test.ts`) — For every self-gated `test/skill-e2e-*.test.ts` named in a touchfiles dep list, the file's `EVALS_TIER` self-gate must match its declared tier in `E2E_TIERS`. Kills the "inert demotion" class where a test is re-tiered in `touchfiles.ts` but the file still gates on the old tier and keeps running in the wrong lane. Unmapped or mixed-tier files are reported, never silently skipped.
 - **Catalog budget** (`test/catalog-budget.test.ts`) — Caps the aggregate discovery surface: the sum of every skill's frontmatter `name` + `description` (what every host loads at discovery, every session) must stay under 1,150 token-equivalents, with a 260-byte per-skill cap. Counting goes through the shared census in `test/helpers/skill-census.ts` (physical files vs authored skills vs registry entries — three deliberately different counts). Adding a skill? The failure message carries the re-measure + ratchet protocol.
+- **Context-budget ratchet** (`test/context-budget-ratchet.test.ts`) — CI ceilings on the two token ledgers the catalog budget doesn't cover: the always-on full-frontmatter aggregate and each skill's per-invocation eager tokens (SKILL.md + forced-read references), graded against `test/fixtures/context-budget.json` via `lib/context-bill.ts`. New skills fail until they have a ceiling; ceilings for removed skills must be pruned. Legitimate growth or a landed reduction: re-run `bun test/helpers/capture-context-budget.ts` and commit the refreshed fixture in the same commit, so the change is a visible decision in the diff.
 
 ### Tier 2: E2E via `claude -p` (~$3.85/run)
 
@@ -418,7 +419,8 @@ When you add a new skill template, all hosts get it automatically:
 1. Create `{skill}/SKILL.md.tmpl`
 2. Run `bun run gen:skill-docs --host all`
 3. The dynamic template discovery picks it up, no static list to update
-4. Commit `{skill}/SKILL.md`, external host output is generated at setup time and gitignored
+4. Budget it: run `bun test/helpers/capture-context-budget.ts` and commit the refreshed `test/fixtures/context-budget.json` — the context-budget ratchet fails any skill without a ceiling
+5. Commit `{skill}/SKILL.md`, external host output is generated at setup time and gitignored
 
 ## Conductor workspaces