diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index adb2aa0879..10ac52dd7b 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -79,3 +79,32 @@ jobs:
       # Build each crate separately, to validate that the feature-gating is working.
       # This is a lighter-weight version of `cargo check-all-features --workspace --release`.
       - run: ./deployments/scripts/check-crate-feature-sets
+
+  # Integration tests that run against the public testnet endpoints.
+  # Temporarily enabling these in CI, to provide assurance during refactoring.
+  testnet-integration:
+    runs-on: buildjet-16vcpu-ubuntu-2204
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          lfs: true
+
+      - name: install nix
+        uses: nixbuild/nix-quick-install-action@v28
+
+      - name: setup nix cache
+        uses: nix-community/cache-nix-action@v5
+        with:
+          primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix') }}
+          restore-prefixes-first-match: nix-${{ runner.os }}-
+          backend: buildjet
+
+      - name: Load rust cache
+        uses: astriaorg/buildjet-rust-cache@v2.5.1
+
+      # Confirm that the nix devshell is buildable and runs at all.
+      - name: validate nix env
+        run: nix develop --command echo hello
+
+      - name: run the testnet integration tests
+        run: nix develop --command just integration-testnet
diff --git a/Cargo.lock b/Cargo.lock
index 01e2f89cca..324b6855da 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5141,11 +5141,14 @@ name = "penumbra-measure"
 version = "0.81.0"
 dependencies = [
  "anyhow",
+ "assert_cmd",
  "bytesize",
  "clap",
  "indicatif",
  "penumbra-compact-block",
  "penumbra-proto",
+ "penumbra-view",
+ "predicates 2.1.5",
  "serde_json",
  "tokio",
  "tonic",
diff --git a/crates/bin/pclientd/Cargo.toml b/crates/bin/pclientd/Cargo.toml
index 40c0906f8a..eafbf96aa1 100644
--- a/crates/bin/pclientd/Cargo.toml
+++ b/crates/bin/pclientd/Cargo.toml
@@ -7,6 +7,7 @@ edition = {workspace = true}
 default = ["std", "download-proving-keys"]
 std = ["ibc-types/std"]
 sct-divergence-check = ["penumbra-view/sct-divergence-check"]
+integration-testnet = []
 # Enable to use rayon parallelism for crypto operations
 parallel = ["penumbra-transaction/parallel"]
 download-proving-keys = ["penumbra-proof-params/download-proving-keys"]
diff --git a/crates/bin/pclientd/tests/testnet.rs b/crates/bin/pclientd/tests/testnet.rs
new file mode 100644
index 0000000000..7275b98cee
--- /dev/null
+++ b/crates/bin/pclientd/tests/testnet.rs
@@ -0,0 +1,90 @@
+#![cfg(feature = "integration-testnet")]
+//! Performs read-only operations against the public Penumbra testnet.
+//! Useful to validate that HTTPS support is working.
+
+use std::process::Command as StdCommand;
+
+use anyhow::Context;
+use assert_cmd::cargo::CommandCargoExt;
+use futures::StreamExt;
+use tempfile::tempdir;
+use tokio::process::Command as TokioCommand;
+
+use pclientd::PclientdConfig;
+use penumbra_keys::test_keys;
+use penumbra_proto::view::v1::view_service_client::ViewServiceClient;
+use penumbra_view::ViewClient;
+
+const NODE_URL: &str = "https://testnet.plinfra.net";
+
+const PCLIENTD_BIND_ADDR: &str = "127.0.0.1:9081";
+
+/// Build config for pclientd, supporting only read operations.
+/// The custody portion is intentionally unset, to avoid side-effects
+/// on the public testnet.
+fn generate_readonly_config() -> anyhow::Result<PclientdConfig> {
+    Ok(PclientdConfig {
+        full_viewing_key: test_keys::FULL_VIEWING_KEY.clone(),
+        grpc_url: NODE_URL.parse()?,
+        bind_addr: PCLIENTD_BIND_ADDR.parse()?,
+        // No custody, so operations are read-only.
+        kms_config: None,
+    })
+}
+
+#[tokio::test]
+/// Start a pclientd process for the testnet wallet, and sync to current height
+/// on the testnet. We don't perform any write actions, so there will be no on-chain
+/// side-effects. Instead, we simply confirm that pclientd can talk to a remote
+/// endpoint and understand the blocks it receives.
+async fn pclientd_sync_against_testnet() -> anyhow::Result<()> {
+    tracing_subscriber::fmt::try_init().ok();
+    // Create a tempdir for the pclientd instance to run in.
+    let data_dir = tempdir().unwrap();
+
+    // 1. Construct a config for the `pclientd` instance:
+    let config = generate_readonly_config()?;
+
+    let config_file_path = data_dir.path().to_owned().join("config.toml");
+    config.save(&config_file_path)?;
+
+    // 2. Run a `pclientd` instance in the background as a subprocess.
+    let home_dir = data_dir.path().to_owned();
+    // Use a std Command so we can use the cargo-specific extensions from assert_cmd
+    let mut pclientd_cmd = StdCommand::cargo_bin("pclientd")?;
+    pclientd_cmd.args(["--home", home_dir.as_path().to_str().unwrap(), "start"]);
+
+    // Convert to an async-aware Tokio command so we can spawn it in the background.
+    let mut pclientd_cmd = TokioCommand::from(pclientd_cmd);
+    // Important: without this, we could accidentally leave the pclientd instance running.
+    pclientd_cmd.kill_on_drop(true);
+
+    let mut pclientd = pclientd_cmd.spawn()?;
+
+    // Wait for the newly spawned daemon to come up.
+    tokio::time::sleep(std::time::Duration::from_millis(2500)).await;
+    if let Some(status) = pclientd.try_wait()? {
+        // An error occurred during startup, probably.
+        anyhow::bail!("pclientd exited early: {status:?}");
+    }
+
+    // 3. Build a client for the daemon we just started.
+    let pclientd_url = format!("http://{}", PCLIENTD_BIND_ADDR);
+    let channel = tonic::transport::Channel::from_shared(pclientd_url)?
+        .connect()
+        .await
+        .context("failed to open channel to test instance of pclientd")?;
+    let mut view_client = ViewServiceClient::new(channel.clone());
+    // let mut custody_client = CustodyServiceClient::new(channel.clone());
+
+    // 4. Use the view protocol to wait for it to sync.
+    let mut status_stream = (&mut view_client as &mut dyn ViewClient)
+        .status_stream()
+        .await?;
+    while let Some(item) = status_stream.as_mut().next().await.transpose()? {
+        tracing::debug!(?item);
+    }
+    // We exit here, dropping the pclientd process handle.
+    // We've verified that we can sync the wallet.
+    Ok(())
+}
diff --git a/crates/bin/pmonitor/Cargo.toml b/crates/bin/pmonitor/Cargo.toml
index 71612426ba..f9799f9f91 100644
--- a/crates/bin/pmonitor/Cargo.toml
+++ b/crates/bin/pmonitor/Cargo.toml
@@ -8,7 +8,8 @@ homepage = { workspace = true }
 license = { workspace = true }
 publish = false
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+integration-testnet = []
 
 [dependencies]
 anyhow = {workspace = true}
diff --git a/crates/bin/pmonitor/tests/testnet.rs b/crates/bin/pmonitor/tests/testnet.rs
new file mode 100644
index 0000000000..53a069a135
--- /dev/null
+++ b/crates/bin/pmonitor/tests/testnet.rs
@@ -0,0 +1,119 @@
+#![cfg(feature = "integration-testnet")]
+//! Integration tests for pmonitor against the public Penumbra testnet.
+//! Mostly useful for verifying that HTTPS connections for gRPC
+//! are well supported.
+use anyhow::Result;
+use assert_cmd::Command as AssertCommand;
+use pcli::config::PcliConfig;
+
+use std::fs::File;
+use std::io::{BufWriter, Write};
+use std::path::{Path, PathBuf};
+use tempfile::{tempdir, NamedTempFile, TempDir};
+
+const NODE_URL: &str = "https://testnet.plinfra.net";
+
+/// Initialize a new pcli wallet at the target directory.
+/// Discards the generated seed phrase.
+fn pcli_init_softkms(pcli_home: &TempDir) -> Result<()> {
+    let mut cmd = AssertCommand::cargo_bin("pcli")?;
+    cmd.args([
+        "--home",
+        pcli_home
+            .path()
+            .to_str()
+            .expect("can convert wallet path to string"),
+        "init",
+        "--grpc-url",
+        NODE_URL,
+        "soft-kms",
+        "generate",
+    ])
+    // send empty string to accept the interstitial seed phrase display
+    .write_stdin("");
+    cmd.assert().success();
+    Ok(())
+}
+
+/// Retrieve a FullViewingKey from a pcli home dir.
+fn get_fvk_from_wallet_dir(pcli_home: &TempDir) -> Result<String> {
+    let pcli_config_path = pcli_home.path().join("config.toml");
+    let pcli_config = PcliConfig::load(
+        pcli_config_path
+            .to_str()
+            .expect("failed to convert pcli wallet path to str"),
+    )?;
+    Ok(pcli_config.full_viewing_key.to_string())
+}
+
+/// Given a list of FVKs, formatted as Strings, write a JSON file
+/// containing those FVKs, for use with pmonitor via the `--fvks` CLI flag.
+fn write_fvks_json(fvks: Vec<String>, dest_filepath: &File) -> Result<()> {
+    let mut w = BufWriter::new(dest_filepath);
+    serde_json::to_writer(&mut w, &fvks)?;
+    w.flush()?;
+    Ok(())
+}
+
+#[test]
+// Initialize an empty (i.e. random) wallet. We don't care about prior balances,
+// because we're not exercising misbehavior: all we care about is that pmonitor
+// can talk to an HTTPS endpoint and understand the blocks it pulls.
+pub fn pmonitor_passes_with_empty_wallet_on_testnet() -> Result<()> {
+    tracing_subscriber::fmt::try_init().ok();
+    let pcli_home = tempdir().unwrap();
+    pcli_init_softkms(&pcli_home)?;
+
+    let fvks = vec![get_fvk_from_wallet_dir(&pcli_home)?];
+    let fvks_json = NamedTempFile::new()?;
+    write_fvks_json(fvks, fvks_json.as_file())?;
+    let pmonitor_pardir = tempfile::tempdir()?;
+    let pmonitor_home = initialize_pmonitor(&pmonitor_pardir, fvks_json.path())?;
+
+    // Run `pmonitor audit` based on the pcli wallets and associated FVKs.
+    let cmd = AssertCommand::cargo_bin("pmonitor")?
+        .args([
+            "--home",
+            pmonitor_home
+                .as_path()
+                .to_str()
+                .expect("failed to parse pmonitor tempdir as directory"),
+            "audit",
+        ])
+        .ok();
+
+    if cmd.is_ok() {
+        Ok(())
+    } else {
+        anyhow::bail!("failed during 'pmonitor audit'")
+    }
+}
+
+/// Generate a config directory for `pmonitor`, based on input FVKs.
+fn initialize_pmonitor(tmpdir: &TempDir, fvks_json: &Path) -> anyhow::Result<PathBuf> {
+    // pmonitor doesn't like pre-existing homedirs so we'll nest this one.
+    let pmonitor_home = tmpdir.path().join("pmonitor");
+
+    let cmd = AssertCommand::cargo_bin("pmonitor")?
+        .args([
+            "--home",
+            pmonitor_home
+                .as_path()
+                .to_str()
+                .expect("failed to parse pmonitor tempdir as dir"),
+            "init",
+            "--grpc-url",
+            NODE_URL,
+            "--fvks",
+            fvks_json
+                .to_str()
+                .expect("failed to parse fvk json tempfile as filepath"),
+        ])
+        .output();
+
+    assert!(
+        cmd.unwrap().status.success(),
+        "failed to initialize pmonitor"
+    );
+    Ok(pmonitor_home)
+}
diff --git a/crates/misc/measure/Cargo.toml b/crates/misc/measure/Cargo.toml
index c065bf9cde..ef48253a4b 100644
--- a/crates/misc/measure/Cargo.toml
+++ b/crates/misc/measure/Cargo.toml
@@ -10,6 +10,9 @@ dist = false
 name = "measure"
 path = "src/main.rs"
 
+[features]
+integration-testnet = []
+
 [dependencies]
 anyhow = {workspace = true}
 bytesize = "1.2"
@@ -17,9 +20,14 @@ clap = {workspace = true, features = ["derive", "env"]}
 indicatif = {workspace = true}
 penumbra-compact-block = {workspace = true, default-features = false}
 penumbra-proto = {workspace = true, features = ["rpc"], default-features = true}
+penumbra-view = {workspace = true}
 serde_json = {workspace = true}
 tokio = {workspace = true, features = ["full"]}
 tonic = {workspace = true, features = ["tls"]}
 tracing = {workspace = true}
 tracing-subscriber = {workspace = true, features = ["env-filter"]}
 url = {workspace = true}
+
+[dev-dependencies]
+assert_cmd = {workspace = true}
+predicates = "2.1"
diff --git a/crates/misc/measure/tests/testnet.rs b/crates/misc/measure/tests/testnet.rs
new file mode 100644
index 0000000000..8e645eb8e7
--- /dev/null
+++ b/crates/misc/measure/tests/testnet.rs
@@ -0,0 +1,23 @@
+#![cfg(feature = "integration-testnet")]
+//! Integration tests for communicating with the public Penumbra testnet.
+//! These tests are off by default, given that they contact remote services,
+//! but are useful to verify functionality for e.g. HTTPS connectivity.
+use assert_cmd::Command;
+
+/// The URL for the public testnet pd endpoint.
+const NODE_URL: &str = "https://testnet.plinfra.net";
+
+// Raise the command timeout because the long-lived testnet will have more blocks to sync.
+// Syncing ~1,000,000 blocks on a mostly-empty wallet should not take ~10 minutes!
+// See GH#4970 for a report of a recent slowdown in pcli syncing operations.
+const TESTNET_TIMEOUT_COMMAND_SECONDS: u64 = 900;
+
+#[test]
+fn stream_blocks_on_testnet() {
+    let mut cmd = Command::cargo_bin("measure").unwrap();
+    cmd.args(["--node", NODE_URL, "stream-blocks"])
+        .timeout(std::time::Duration::from_secs(
+            TESTNET_TIMEOUT_COMMAND_SECONDS,
+        ));
+    cmd.assert().success();
+}
diff --git a/justfile b/justfile
index bb5f5d29d6..1d86198fbe 100644
--- a/justfile
+++ b/justfile
@@ -47,6 +47,10 @@ metrics:
 rustdocs:
     ./deployments/scripts/rust-docs
 
+# Run integration tests against the testnet, for validating HTTPS support
+integration-testnet:
+  cargo nextest run --release --features integration-testnet -E 'test(/_testnet$/)'
+
 # Run smoke test suite, via process-compose config.
 smoke:
     ./deployments/scripts/warn-about-pd-state