feat: dsh-session-projection-cache — durable projection checkpoints and the cold-read ladder

New package on the domain data form: one session_projcache record per
session (key → {stateVersion, observedSeq, state}), landing beside
workspace.json under the shipped json backend. Write policy: two mandatory
points (turn/end + session disposal) with count/interval throttling between
them (both Config fields required — flush cadence is a deployment choice);
every background write is fail-soft (log + stay stale, self-heal on the
next write or cold read). coldSnapshot(id) runs the read ladder — cached
rows + persistence readFrom from the registry's anchored restore floor +
registry restore + fail-soft write-back — detecting crash-repair-shrunk
logs via the one-below anchor and degrading to a single full re-read.
Mounted in apps/cli/cordis.yml (writeEveryEvents 200 / writeIntervalMs
5000).

packages/session-projection/session-projection-cache/package.json

@@ -0,0 +1,52 @@
+{
+  "name": "@deepseek-ai/dsh-session-projection-cache",
+  "description": "Persisted projection cache (ctx.sessionProjectionCache): durable per-session projection checkpoints over the domain data form, throttled write-behind, and the cold-read ladder (cache row + persistence tail replay)",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "main": "lib/index.js",
+  "types": "lib/types/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./lib/types/index.d.ts",
+      "default": "./lib/index.js"
+    },
+    "./invariant": {
+      "types": "./lib/types/invariant.d.ts",
+      "default": "./lib/invariant.js"
+    },
+    "./src/*": "./src/*",
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "lib/index.js",
+    "lib/invariant.js",
+    "lib/types/**/*.js",
+    "lib/types/**/*.d.ts",
+    "lib/types/**/*.d.ts.map",
+    "src"
+  ],
+  "license": "BSD-3-Clause",
+  "dependencies": {
+    "schemastery": "^3.18.0",
+    "zod": "^4.4.3"
+  },
+  "peerDependencies": {
+    "@deepseek-ai/dsh-invariants": "^0.0.1",
+    "@deepseek-ai/dsh-session": "^0.0.1",
+    "@deepseek-ai/dsh-session-persistence": "^0.0.1",
+    "@deepseek-ai/dsh-session-projection": "^0.0.1",
+    "@deepseek-ai/dsh-storage-domain": "^0.0.1",
+    "cordis": "^4.0.0-rc.7"
+  },
+  "devDependencies": {
+    "@deepseek-ai/dsh-invariants": "workspace:^",
+    "@deepseek-ai/dsh-session": "workspace:^",
+    "@deepseek-ai/dsh-session-persistence": "workspace:^",
+    "@deepseek-ai/dsh-session-projection": "workspace:^",
+    "@deepseek-ai/dsh-storage": "workspace:^",
+    "@deepseek-ai/dsh-storage-domain": "workspace:^",
+    "@deepseek-ai/dsh-storage-json": "workspace:^",
+    "cordis": "^4.0.0-rc.7"
+  }
+}