diff --git a/devlog/2026-08-15_viable-ranges/REQ.md b/devlog/2026-08-15_viable-ranges/REQ.md
new file mode 100644
index 0000000..02978bf
--- /dev/null
+++ b/devlog/2026-08-15_viable-ranges/REQ.md
@@ -0,0 +1,31 @@
+# REQ - Filter status compressible ranges via billion-context-kit
+
+- Task ID: `2026-08-15_viable-ranges`
+- Home Repo: `billion-context-opencode`
+- Created: 2026-08-15
+- Status: Done
+- Priority: P2
+- Owner: 5258MF
+- References: `packages/core/src/status-tool.ts`; PR #19
+
+## 1. Background & Problem Statement
+
+- **Context**: The sibling adapters (billion-context-omp, billion-context-pi) hit a production failure mode: the nudge/status recommendation lists can contain fragmented ranges (e.g. a 16-token one-message ack). A model that batches the whole list into one compress call gets atomically rejected by acp-kernel — `minSummaryLength` (50 chars) cannot be satisfied by a tiny range, and the kernel validates the batch as a whole. omp issue evidence: 14-range list containing a 16-token range, every batch attempt failed.
+- **Current behavior (symptom)**: `packages/core/src/status-tool.ts` lists `nudge.compressibleRanges` unfiltered, so sub-viability fragments are recommended to the model/user.
+- **Expected behavior**: every surface that recommends ranges (this PR: the status tool) applies the shared viability floor from `billion-context-kit` (`viableRanges`, `VIABLE_RANGE_MIN_TOKENS = 200`).
+
+## 2. Requirements
+
+- R1: `status-tool.ts` compressible list is filtered by `viableRanges` before rendering.
+- R2: No kernel bump — opencode stays on acp-kernel 0.0.19; the kit's `viableRanges` has no kernel dependency, so pulling the kit does not change kernel semantics.
+- R3: The kit dependency is an exact pin (build-time, bundled inline); transitional git pin `git+https#v0.1.1` now swapped to npm `0.1.1` after publication.
+
+## 3. Non-Goals
+
+- Adopting the kit panel (`buildStatusPanel`) — larger surface, follow-up when the repo stabilizes.
+- Filtering the nudge injection itself (omp/pi do this in their adapters; opencode's nudge path is host-side and out of scope here).
+
+## 4. Acceptance Criteria
+
+- AC1: `npm run typecheck --workspaces` and `npm test` (54/54) pass.
+- AC2: Status output contains no compressible range below 200 tokens.
diff --git a/devlog/2026-08-15_viable-ranges/WORKLOG.md b/devlog/2026-08-15_viable-ranges/WORKLOG.md
new file mode 100644
index 0000000..292335f
--- /dev/null
+++ b/devlog/2026-08-15_viable-ranges/WORKLOG.md
@@ -0,0 +1,27 @@
+# WORKLOG - Filter status compressible ranges via billion-context-kit
+
+- Task ID: `2026-08-15_viable-ranges`
+- Home Repo: `billion-context-opencode`
+- Status: Done
+- Updated: 2026-08-15
+
+## 1. Summary
+
+- **What was done**: Wired `billion-context-kit`'s `viableRanges` (>=200-token floor) into the status tool's compressible-range list, and pinned the kit dependency to the published npm version (`0.1.1`, was the transitional `git+https#v0.1.1`).
+
+## 2. Changes
+
+- `packages/core/package.json`: devDependency `billion-context-kit@0.1.1` (exact pin, bundled inline at build time).
+- `packages/core/src/status-tool.ts`: `compressibleRanges` passed through `viableRanges()` before rendering.
+- `package-lock.json` refreshed via `npm install --package-lock-only -w packages/core`.
+
+## 3. Verification
+
+- `npm run typecheck --workspaces`: clean.
+- `npm test`: 54/54 pass.
+- CI: build matrix (22/24) green; pr-validation initially failed on the missing devlog entry (this entry) — added, retriggered.
+
+## 4. Notes
+
+- acp-kernel intentionally stays at 0.0.19: `viableRanges` is a pure function with no kernel dependency, so no kernel semantics change rides along.
+- The 200-token floor matches the sibling adapters (omp PR #20/#15, pi PR #148) — all three now share the same viability rule from one source.
diff --git a/package-lock.json b/package-lock.json
index b8d6a67..2aaeba1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -953,6 +953,28 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/billion-context-kit": {
+      "version": "0.1.1",
+      "resolved": "git+ssh://git@github.com/ranxianglei/billion-context-kit.git#6e1577002fbb8752f9530d785927e6bcceb28ac6",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "acp-kernel": "0.0.23"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/billion-context-kit/node_modules/acp-kernel": {
+      "version": "0.0.23",
+      "resolved": "https://registry.npmjs.org/acp-kernel/-/acp-kernel-0.0.23.tgz",
+      "integrity": "sha512-bG28aYfBda8z34fsaoNc4QBix4gRtQDQznR6G4XBaz9z1xgxdmdYtazQQMBjxnfEL9yCrDb9CTpkl7IXWiuviA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=20"
+      }
+    },
     "node_modules/billion-context-opencode": {
       "resolved": "packages/billion-context-opencode",
       "link": true
@@ -2098,6 +2120,7 @@
       },
       "devDependencies": {
         "@types/node": "^22.10.0",
+        "billion-context-kit": "0.1.1",
         "typescript": "^5.7.0"
       }
     },
diff --git a/packages/core/package.json b/packages/core/package.json
index 61f6e34..9f5604b 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -14,6 +14,7 @@
   },
   "devDependencies": {
     "@types/node": "^22.10.0",
+    "billion-context-kit": "0.1.1",
     "typescript": "^5.7.0"
   }
 }
diff --git a/packages/core/src/status-tool.ts b/packages/core/src/status-tool.ts
index 58fa29d..1ede90a 100644
--- a/packages/core/src/status-tool.ts
+++ b/packages/core/src/status-tool.ts
@@ -1,5 +1,6 @@
 import { z } from "zod"
 import { buildStatusReport, defaultCountTokens, formatRanges } from "acp-kernel"
+import { viableRanges } from "billion-context-kit"
 import type { AcpRuntime } from "./runtime.js"
 import type { ToolDef } from "./compress-tool.js"
 import { estimateTokens, collectCoveredMessageIds } from "./tokens.js"
@@ -53,7 +54,10 @@ async function handleStatus(args: Record<string, unknown>, runtime: AcpRuntime,
   if (args.scope) return base
 
   const nudge = turn.nudge
-  const ranges = nudge?.compressibleRanges ?? []
+  // Kit filter: fragmented ranges (<200 tokens) cannot carry a meaningful
+  // summary and would fail the kernel's atomic batch validation — same guard
+  // as the omp/pi adapters (billion-context-kit viableRanges).
+  const ranges = viableRanges(nudge?.compressibleRanges ?? [])
   const protectedRanges = nudge?.protectedRanges ?? []
 
   const extra: string[] = []