diff --git a/ci-broker.md b/ci-broker.md
index bea74d56..dbbaed8a 100644
--- a/ci-broker.md
+++ b/ci-broker.md
@@ -236,6 +236,8 @@ The Git repository must exist.
 ~~~scenario
 then directory reppy exists
 then directory reppy/.git exists
+then file reppy/file.dat exists
+then file reppy/foobar does not exist
 when I run, in reppy, git show
 then stdout matches regex ^commit
 ~~~
@@ -1230,6 +1232,53 @@ triggers:
 ~~~
 
 
+## Filter predicate `HasFile`
+
+_Want:_ We can allow an event if its commit contains a file or
+directory by this name.
+
+_Why:_ This is so that the user can choose a suitable adapter.
+
+~~~scenario
+given a Radicle node, with CI configured with broker.yaml and adapter dummy.sh
+given a Git repository xyzzy in the Radicle node
+
+given file config.yaml from filter-hasfile-missing.yaml
+when I run cibtool --db ci-broker.db event add --repo xyzzy --ref main --commit HEAD --kind branch-created
+when I run ./env.sh cib --config config.yaml queued
+when I run cibtool --db ci-broker.db run list --json
+then stdout doesn't contain "main"
+
+given file config.yaml from filter-hasfile.yaml
+when I run cibtool --db ci-broker.db event add --repo xyzzy --ref main --commit HEAD --kind branch-created
+when I run ./env.sh cib --config config.yaml queued
+when I run cibtool --db ci-broker.db run list --json
+then stdout contains "main"
+~~~
+
+~~~{#filter-hasfile.yaml .file .json}
+db: ci-broker.db
+adapters:
+  default:
+    command: ./adapter.sh
+triggers:
+  - adapter: default
+    filters:
+      - !HasFile "file.dat"
+~~~
+
+~~~{#filter-hasfile-missing.yaml .file .json}
+db: ci-broker.db
+adapters:
+  default:
+    command: ./adapter.sh
+triggers:
+  - adapter: default
+    filters:
+      - !HasFile "does-not-exist"
+~~~
+
+
 # Acceptance criteria for test tooling
 
 The event synthesizer is a helper to feed the CI broker node events in
diff --git a/src/filter.rs b/src/filter.rs
index 60d3c02f..81e6c990 100644
--- a/src/filter.rs
+++ b/src/filter.rs
@@ -4,7 +4,7 @@ use serde::{Deserialize, Serialize};
 
 use radicle::{
     cob::patch::PatchId,
-    git::RefString,
+    git::{raw::ObjectType, RefString},
     node::NodeId,
     prelude::{Profile, RepoId},
     storage::git::Repository,
@@ -79,6 +79,9 @@ pub enum EventFilter {
     /// Change originated from specific node.
     Node(NodeId),
 
+    /// Commit in change contains a file or directory with this name.
+    HasFile(PathBuf),
+
     /// Allow any event.
     Allow,
 
@@ -117,19 +120,21 @@ impl EventFilter {
                 from_node,
                 repo,
                 branch,
-                ..
+                tip,
             }) => match self {
                 Self::Node(wanted) => from_node == wanted,
                 Self::Repository(wanted) => repo == wanted,
                 Self::Branch(wanted) => branch == wanted,
                 Self::DefaultBranch => is_default_branch(repo, branch),
                 Self::BranchCreated => true,
+                Self::HasFile(wanted) => has_file(repo, tip, wanted),
                 _ => false,
             },
             CiEvent::V1(CiEventV1::BranchUpdated {
                 from_node,
                 repo,
                 branch,
+                tip,
                 ..
             }) => match self {
                 Self::Node(wanted) => from_node == wanted,
@@ -137,43 +142,49 @@ impl EventFilter {
                 Self::Branch(wanted) => branch == wanted,
                 Self::DefaultBranch => is_default_branch(repo, branch),
                 Self::BranchUpdated => true,
+                Self::HasFile(wanted) => has_file(repo, tip, wanted),
                 _ => false,
             },
             CiEvent::V1(CiEventV1::BranchDeleted {
                 from_node,
                 repo,
                 branch,
-                ..
+                tip,
             }) => match self {
                 Self::Node(wanted) => from_node == wanted,
                 Self::Repository(wanted) => repo == wanted,
                 Self::Branch(wanted) => branch == wanted,
                 Self::DefaultBranch => is_default_branch(repo, branch),
                 Self::BranchDeleted => true,
+                Self::HasFile(wanted) => has_file(repo, tip, wanted),
                 _ => false,
             },
             CiEvent::V1(CiEventV1::PatchCreated {
                 from_node,
                 repo,
                 patch,
+                new_tip,
                 ..
             }) => match self {
                 Self::Node(wanted) => from_node == wanted,
                 Self::Repository(wanted) => repo == wanted,
                 Self::Patch(wanted) => *patch == PatchId::from(wanted),
                 Self::PatchCreated => true,
+                Self::HasFile(wanted) => has_file(repo, new_tip, wanted),
                 _ => false,
             },
             CiEvent::V1(CiEventV1::PatchUpdated {
                 from_node,
                 repo,
                 patch,
+                new_tip,
                 ..
             }) => match self {
                 Self::Node(wanted) => from_node == wanted,
                 Self::Repository(wanted) => repo == wanted,
                 Self::Patch(wanted) => *patch == PatchId::from(wanted),
                 Self::PatchUpdated => true,
+                Self::HasFile(wanted) => has_file(repo, new_tip, wanted),
                 _ => false,
             },
         };
@@ -212,6 +223,35 @@ fn get_default_branch(repo_id: &RepoId) -> Result<String, Box<dyn std::error::Er
     Ok(def)
 }
 
+fn has_file(repo_id: &RepoId, oid: &Oid, filename: &Path) -> bool {
+    fn helper(
+        repo_id: &RepoId,
+        oid: Oid,
+        filename: &Path,
+    ) -> Result<bool, Box<dyn std::error::Error>> {
+        let profile = Profile::load()?;
+        let repo = Repository::open(profile.storage.path().join(repo_id.canonical()), *repo_id)?;
+
+        let obj = repo.backend.find_object(*oid, Some(ObjectType::Commit))?;
+        let commit = if let Ok(commit) = obj.into_commit() {
+            commit
+        } else {
+            return Ok(false);
+        };
+        let tree = commit.tree()?;
+        let entry = if let Ok(entry) = tree.get_path(filename) {
+            entry
+        } else {
+            return Ok(false);
+        };
+        let obj = entry.to_object(&repo.backend)?;
+        let ok = obj.into_blob().is_ok();
+        Ok(ok)
+    }
+
+    helper(repo_id, *oid, filename).unwrap_or(false)
+}
+
 #[derive(Deserialize)]
 struct Filters {
     filters: Vec<EventFilter>,