diff --git a/deploy/README.md b/deploy/README.md
index 0383f00f..fa1a40cf 100644
--- a/deploy/README.md
+++ b/deploy/README.md
@@ -87,6 +87,7 @@ RECTIFICATION_PRICE_CREDITS=3
 
 # Required to encrypt/decrypt model-provider API keys stored in the admin database.
 # Base64 decoding must produce exactly 32 random bytes; do not reuse other keys.
+# Staging migration/deploy creates this once when absent and removes legacy model API-key settings.
 MODEL_PROVIDER_CONFIG_ENCRYPTION_KEY=<independent-base64-encoded-32-byte-key>
 # OpenAI-compatible origins must be explicitly server-allowlisted.
 # MODEL_PROVIDER_BASE_URL_ALLOWLIST=https://api.deepseek.com
diff --git a/deploy/prepare-staging-model-provider-env.sh b/deploy/prepare-staging-model-provider-env.sh
new file mode 100755
index 00000000..a377811b
--- /dev/null
+++ b/deploy/prepare-staging-model-provider-env.sh
@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+set -euo pipefail
+set +x
+
+ENV_FILE="${1:-.env.staging}"
+if [ ! -f "$ENV_FILE" ] || [ -L "$ENV_FILE" ]; then
+  echo "staging environment file is missing or unsafe: $ENV_FILE" >&2
+  exit 1
+fi
+
+legacy_pattern='^(OPENAI_API_KEY|ANTHROPIC_API_KEY|DEEPSEEK_API_KEY|LLM_API_KEY|LLM_MODELS_JSON|LLM_BASE_URL|LLM_MODEL|LLM_DEFAULT_MODEL_ID|LLM_PROVIDER_ID|MASTRA_MODEL|MODEL_PROVIDER_[A-Z0-9_]+_API_KEY)='
+key_count="$(grep -Ec '^MODEL_PROVIDER_CONFIG_ENCRYPTION_KEY=' "$ENV_FILE" || true)"
+if [ "$key_count" -gt 1 ]; then
+  echo "duplicate staging model provider encryption key" >&2
+  exit 1
+fi
+
+if mode="$(stat -c '%a' "$ENV_FILE" 2>/dev/null)"; then
+  owner="$(stat -c '%u' "$ENV_FILE")"
+  group="$(stat -c '%g' "$ENV_FILE")"
+else
+  mode="$(stat -f '%Lp' "$ENV_FILE")"
+  owner="$(stat -f '%u' "$ENV_FILE")"
+  group="$(stat -f '%g' "$ENV_FILE")"
+fi
+temporary="$(mktemp "${ENV_FILE}.tmp.XXXXXX")"
+trap 'rm -f -- "$temporary"' EXIT
+
+grep -Ev "$legacy_pattern" "$ENV_FILE" > "$temporary" || true
+if [ "$key_count" -eq 0 ]; then
+  key="$(openssl rand -base64 32 | tr -d '\n')"
+  [[ "$key" =~ ^[A-Za-z0-9+/]{43}=$ ]] || exit 1
+  printf 'MODEL_PROVIDER_CONFIG_ENCRYPTION_KEY=%s\n' "$key" >> "$temporary"
+fi
+
+chmod "$mode" "$temporary"
+chown "$owner:$group" "$temporary"
+mv -f -- "$temporary" "$ENV_FILE"
+trap - EXIT
diff --git a/deploy/run-staging-deploy.sh b/deploy/run-staging-deploy.sh
index 7a52c90d..4fd18af4 100755
--- a/deploy/run-staging-deploy.sh
+++ b/deploy/run-staging-deploy.sh
@@ -126,6 +126,7 @@ EXPECTED_STAGING_ENV_OWNER_UID="$(stat -c '%u' "$DEPLOY_PATH" 2>/dev/null || sta
   exit 1
 }
 export EXPECTED_STAGING_ENV_OWNER_UID
+bash deploy/prepare-staging-model-provider-env.sh .env.staging
 bash deploy/validate-staging-env.sh \
   .env.staging staging.jyotisha.chat deploy/Caddyfile.staging
 bash deploy/validate-staging-database-env.sh .env.staging.database
diff --git a/deploy/run-staging-migration.sh b/deploy/run-staging-migration.sh
index 60dda620..743e30a8 100755
--- a/deploy/run-staging-migration.sh
+++ b/deploy/run-staging-migration.sh
@@ -78,6 +78,7 @@ EXPECTED_STAGING_ENV_OWNER_UID="$(stat -c '%u' "$DEPLOY_PATH" 2>/dev/null || sta
   exit 1
 }
 export EXPECTED_STAGING_ENV_OWNER_UID
+bash deploy/prepare-staging-model-provider-env.sh .env.staging
 bash deploy/validate-staging-env.sh \
   .env.staging staging.jyotisha.chat deploy/Caddyfile.staging
 bash deploy/validate-staging-database-env.sh .env.staging.database
diff --git a/frontend/tests/health-deployment.test.ts b/frontend/tests/health-deployment.test.ts
index 1c6cac2c..253cd53e 100644
--- a/frontend/tests/health-deployment.test.ts
+++ b/frontend/tests/health-deployment.test.ts
@@ -4,6 +4,7 @@ import {
   mkdtempSync,
   readFileSync,
   rmSync,
+  statSync,
   writeFileSync,
 } from "node:fs";
 import { tmpdir } from "node:os";
@@ -222,6 +223,33 @@ test("staging deploy consumes only the isolated staging environment and tested r
   assert.match(syncController, /--exclude='\/backups\/'/);
 });
 
+test("staging model provider env preparation removes legacy settings and keeps one stable key", () => {
+  const prepare = fileURLToPath(
+    new URL("../../deploy/prepare-staging-model-provider-env.sh", import.meta.url),
+  );
+  const root = mkdtempSync(join(tmpdir(), "jyotisha-staging-model-env-"));
+  const envFile = join(root, ".env.staging");
+  try {
+    writeFileSync(envFile, "APP_ENV_FILE=../.env.staging\nOPENAI_API_KEY=legacy\nLLM_MODEL=legacy\n");
+    chmodSync(envFile, 0o600);
+    const first = spawnSync("bash", [prepare, envFile], { encoding: "utf8" });
+    assert.equal(first.status, 0, first.stderr);
+    const prepared = readFileSync(envFile, "utf8");
+    assert.match(prepared, /^APP_ENV_FILE=\.\.\/\.env\.staging$/m);
+    assert.doesNotMatch(prepared, /^(OPENAI_API_KEY|LLM_MODEL)=/m);
+    const key = prepared.match(/^MODEL_PROVIDER_CONFIG_ENCRYPTION_KEY=([A-Za-z0-9+/]{43}=)$/m)?.[1];
+    assert.ok(key);
+    assert.equal(statSync(envFile).mode & 0o777, 0o600);
+
+    const second = spawnSync("bash", [prepare, envFile], { encoding: "utf8" });
+    assert.equal(second.status, 0, second.stderr);
+    const secondKey = readFileSync(envFile, "utf8").match(/^MODEL_PROVIDER_CONFIG_ENCRYPTION_KEY=([A-Za-z0-9+/]{43}=)$/m)?.[1];
+    assert.equal(secondKey, key);
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
 test("staging env validator rejects selector drift, duplicates, and unsafe permissions", () => {
   const validator = fileURLToPath(
     new URL("../../deploy/validate-staging-env.sh", import.meta.url),
diff --git a/frontend/tests/staging-backend-workflows.test.ts b/frontend/tests/staging-backend-workflows.test.ts
index 3019e20f..4c9756b9 100644
--- a/frontend/tests/staging-backend-workflows.test.ts
+++ b/frontend/tests/staging-backend-workflows.test.ts
@@ -649,6 +649,7 @@ test("first immutable deployment rolls back to validated local image IDs", () =>
   writeFileSync(join(deploymentPath, ".state", "deployed-revision"), `${previousSha}\n`);
   for (const script of [
     join(incomingDeploy, "sync-staging-tree.sh"),
+    join(liveDeploy, "prepare-staging-model-provider-env.sh"),
     join(liveDeploy, "validate-staging-env.sh"),
     join(liveDeploy, "validate-staging-database-env.sh"),
   ]) {
@@ -726,6 +727,7 @@ test("normal deployment checks migrations but never applies them", () => {
   assert.match(runner, /^#!\/usr\/bin\/env bash\nset -euo pipefail\nset \+x\n/);
   assert.match(runner, /-f deploy\/docker-compose\.staging\.yml/);
   assertOrder(runner, [
+    "prepare-staging-model-provider-env.sh",
     "validate-staging-env.sh",
     "validate-staging-database-env.sh",
     "compose=(",