diff --git a/tests/authenticated_stream_test.nu b/tests/authenticated_stream_test.nu
index b808875..3a9049d 100644
--- a/tests/authenticated_stream_test.nu
+++ b/tests/authenticated_stream_test.nu
@@ -1,65 +1,6 @@
 #!/usr/bin/env nu
 use common.nu *
 
-# simplistic dotenv parser
-def load-env-file [] {
-    if (".env" | path exists) {
-        let content = (open .env)
-        $content | lines 
-        | where { |x| ($x | str trim | is-empty) == false and ($x | str trim | str starts-with "#") == false } 
-        | each { |x| 
-            let parts = ($x | split row "=" -n 2)
-            { key: ($parts.0 | str trim), value: ($parts.1 | str trim | str trim -c '"' | str trim -c "'") } 
-        }
-        | reduce -f {} { |it, acc| $acc | insert $it.key $it.value }
-    } else {
-        {}
-    }
-}
-
-def authenticate [pds_url: string, identifier: string, password: string] {
-    print $"authenticating with ($pds_url) for ($identifier)..."
-    let resp = (http post -t application/json $"($pds_url)/xrpc/com.atproto.server.createSession" {
-        identifier: $identifier,
-        password: $password
-    })
-    return $resp
-}
-
-def create-record [pds_url: string, jwt: string, repo: string, collection: string, record: any] {
-    http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.repo.createRecord" {
-        repo: $repo,
-        collection: $collection,
-        record: $record
-    }
-}
-
-def delete-record [pds_url: string, jwt: string, repo: string, collection: string, rkey: string] {
-    http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.repo.deleteRecord" {
-        repo: $repo,
-        collection: $collection,
-        rkey: $rkey
-    }
-}
-
-def deactivate-account [pds_url: string, jwt: string] {
-    print "deactivating account..."
-    http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.server.deactivateAccount" {}
-}
-
-def activate-account [pds_url: string, jwt: string] {
-    print "activating account..."
-    curl -X POST -H "Content-Type: application/json" -H $"Authorization: Bearer ($jwt)" $"($pds_url)/xrpc/com.atproto.server.activateAccount"
-}
-
-def resolve-pds [did: string] {
-    print $"resolving pds for ($did)..."
-    let doc = (http get $"https://plc.wtf/($did)" | from json)
-    let pds = ($doc.service | where type == "AtprotoPersonalDataServer" | first).serviceEndpoint
-    print $"resolved pds: ($pds)"
-    return $pds
-}
-
 def main [] {
     let env_vars = load-env-file
     let did = ($env_vars | get --optional TEST_REPO)
diff --git a/tests/common.nu b/tests/common.nu
index 4fab236..2afae64 100644
--- a/tests/common.nu
+++ b/tests/common.nu
@@ -1,3 +1,54 @@
+export def load-env-file [] {
+    if (".env" | path exists) {
+        let content = (open .env)
+        $content | lines
+        | where { |x| ($x | str trim | is-empty) == false and ($x | str trim | str starts-with "#") == false }
+        | each { |x|
+            let parts = ($x | split row "=" -n 2)
+            { key: ($parts.0 | str trim), value: ($parts.1 | str trim | str trim -c '"' | str trim -c "'") }
+        }
+        | reduce -f {} { |it, acc| $acc | insert $it.key $it.value }
+    } else {
+        {}
+    }
+}
+
+export def resolve-pds [did: string] {
+    let doc = (http get $"https://plc.wtf/($did)" | from json)
+    ($doc.service | where type == "AtprotoPersonalDataServer" | first).serviceEndpoint
+}
+
+export def authenticate [pds_url: string, identifier: string, password: string] {
+    http post -t application/json $"($pds_url)/xrpc/com.atproto.server.createSession" {
+        identifier: $identifier,
+        password: $password
+    }
+}
+
+export def create-record [pds_url: string, jwt: string, repo: string, collection: string, record: any] {
+    http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.repo.createRecord" {
+        repo: $repo,
+        collection: $collection,
+        record: $record
+    }
+}
+
+export def delete-record [pds_url: string, jwt: string, repo: string, collection: string, rkey: string] {
+    http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.repo.deleteRecord" {
+        repo: $repo,
+        collection: $collection,
+        rkey: $rkey
+    }
+}
+
+export def deactivate-account [pds_url: string, jwt: string] {
+    http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.server.deactivateAccount" {}
+}
+
+export def activate-account [pds_url: string, jwt: string] {
+    curl -X POST -H "Content-Type: application/json" -H $"Authorization: Bearer ($jwt)" $"($pds_url)/xrpc/com.atproto.server.activateAccount"
+}
+
 # build the hydrant binary
 export def build-hydrant [] {
     print "building hydrant..."
diff --git a/tests/signal_filter_test.nu b/tests/signal_filter_test.nu
new file mode 100644
index 0000000..dde759e
--- /dev/null
+++ b/tests/signal_filter_test.nu
@@ -0,0 +1,112 @@
+#!/usr/bin/env nu
+use common.nu *
+
+def main [] {
+    let env_vars = load-env-file
+    let did = ($env_vars | get --optional TEST_REPO)
+    let password = ($env_vars | get --optional TEST_PASSWORD)
+
+    if ($did | is-empty) or ($password | is-empty) {
+        print "error: TEST_REPO and TEST_PASSWORD must be set in .env"
+        exit 1
+    }
+
+    let port = 3007
+    let url = $"http://localhost:($port)"
+    let db_path = (mktemp -d -t hydrant_signal_test.XXXXXX)
+    let collection = "app.bsky.feed.post"
+
+    print $"database path: ($db_path)"
+
+    let pds_url = resolve-pds $did
+    print $"resolved pds: ($pds_url)"
+
+    let session = authenticate $pds_url $did $password
+    let jwt = $session.accessJwt
+    print "authenticated"
+
+    let binary = build-hydrant
+    let instance = start-hydrant $binary $db_path $port
+
+    mut test_passed = false
+
+    if (wait-for-api $url) {
+        # configure signal mode: index app.bsky.feed.post from anyone on the network
+        print "configuring signal mode..."
+        http patch -t application/json $"($url)/filter" {
+            mode: "signal",
+            signals: [$collection]
+        }
+
+        # verify filter state
+        let filter = (http get $"($url)/filter")
+        print $"filter state: ($filter | to json)"
+
+        if $filter.mode != "signal" {
+            print "FAILED: mode was not set to signal"
+        } else if not ($filter.signals | any { |s| $s == $collection }) {
+            print $"FAILED: ($collection) not in signals"
+        } else {
+            print "filter configured correctly"
+
+            # wait a moment for the firehose to connect and the filter to take effect
+            sleep 3sec
+
+            let timestamp = (date now | format date "%Y-%m-%dT%H:%M:%SZ")
+            let record_data = {
+                "$type": $collection,
+                text: $"hydrant signal filter test ($timestamp)",
+                createdAt: $timestamp
+            }
+
+            print "creating post..."
+            let create_res = (http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.repo.createRecord" {
+                repo: $did,
+                collection: $collection,
+                record: $record_data
+            })
+            let rkey = ($create_res.uri | split row "/" | last)
+            print $"created: ($create_res.uri)"
+
+            # give hydrant time to receive and process the firehose event
+            sleep 5sec
+
+            # verify the record was indexed
+            print "checking indexed record..."
+            let result = (try {
+                http get $"($url)/xrpc/com.atproto.repo.getRecord?repo=($did)&collection=($collection)&rkey=($rkey)"
+            } catch {
+                null
+            })
+
+            if ($result | is-empty) {
+                print "FAILED: record not found in hydrant index"
+            } else {
+                print $"indexed record cid: ($result.cid)"
+                print "test PASSED: signal filter correctly indexed the post"
+                $test_passed = true
+            }
+
+            # cleanup: delete the test post
+            print "cleaning up test post..."
+            try {
+                http post -t application/json -H ["Authorization" $"Bearer ($jwt)"] $"($pds_url)/xrpc/com.atproto.repo.deleteRecord" {
+                    repo: $did,
+                    collection: $collection,
+                    rkey: $rkey
+                }
+            }
+        }
+    } else {
+        print "hydrant failed to start"
+    }
+
+    print "stopping hydrant..."
+    try { kill -9 $instance.pid }
+
+    if $test_passed {
+        exit 0
+    } else {
+        exit 1
+    }
+}