feat(launch): add opt-in entrypoint relabeling via CPROXY_ENTRYPOINT

README.md

@@ -101,6 +101,10 @@ with a flag go to claude, so `cproxy run --pool cvp -- --resume x` works
 like cswap's run. Ambient Anthropic credentials and `CPROXY_*` secrets are
 stripped from the child's environment, and `CLAUDE_CODE_PROMPT_CACHE_TTL=1h`
 is set unless you set it yourself (see [Prompt cache TTL](#prompt-cache-ttl)).
+`CLAUDE_CODE_ENTRYPOINT` is left as the environment has it — stock behaviour
+— unless `CPROXY_ENTRYPOINT` opts the launch into the custom-label workaround
+for the faster-draining `sdk-*` rate (see
+[The 5-hour meter and the entrypoint label](#the-5-hour-meter-and-the-entrypoint-label)).
 The child shares cproxy's process
 group (Ctrl+C reaches it directly), and cproxy exits with the child's exit
 code. `--isolated` runs a private proxy for one launch instead.
@@ -221,6 +225,7 @@ orbs, CI, or anywhere you don't want a credentials file:
 | `CPROXY_CLIENT_TOKENS` | several client tokens in one variable: `name:token[:scopes]`, scopes `+`-separated |
 | `CPROXY_UPSTREAM` | upstream base URL (default `https://api.anthropic.com`) |
 | `CPROXY_HOME` | config directory (default `~/.cproxy`) |
+| `CPROXY_ENTRYPOINT` | custom `CLAUDE_CODE_ENTRYPOINT` label for the launch (unset, `off` or `0` leaves the variable untouched) |
 
 One variable per account is the easiest to manage as secrets: adding,
 rotating or removing an account touches only its own variable.
@@ -312,6 +317,42 @@ set it yourself (`5m`, or `1h`) to override. Clients of a shared
 subscriber, Claude Code then keeps 1h even after the account is past its plan
 limits.
 
+## The 5-hour meter and the entrypoint label
+
+Anthropic's plan meters currently charge headless Claude Code — `claude -p`
+and Agent SDK apps like T3 Code — about 1.7× to 2.9× more of the 5-hour
+window per token than the same tokens from the interactive CLI, because those
+sessions label their requests `sdk-cli`/`sdk-ts` and that label is what is
+weighted ([anthropics/claude-code#97074](https://github.com/anthropics/claude-code/issues/97074),
+[pingdotgg/t3code#24649](https://github.com/pingdotgg/t3code/issues/24649)).
+Weekly limits are not affected. Every request carries the label, as
+`cc_entrypoint` in its billing block and in the User-Agent, and it comes from
+`CLAUDE_CODE_ENTRYPOINT` in Claude Code's environment.
+
+cproxy can apply the same workaround: `cproxy run` and the shim launch claude
+with `CLAUDE_CODE_ENTRYPOINT=$CPROXY_ENTRYPOINT` (any custom name, e.g.
+`acme-agent`), so its requests carry a custom client label — the same
+workaround T3 Code and Paseo ship — and skip the `sdk-*` weighting. The name
+must be custom: headless claude rewrites the literal `cli` (the interactive
+TUI's default) to `sdk-cli`, so `cli` and `sdk-*` values are treated like
+unset. With the variable unset — or `off` or `0` — cproxy leaves
+`CLAUDE_CODE_ENTRYPOINT` exactly as the environment has it, including
+absent: stock claude behaviour. An interactive TUI launched through cproxy
+needs no label either way; claude defaults it to `cli` itself.
+
+Clients of a shared `cproxy serve` set it in their own environment, like the
+prompt cache TTL:
+
+```sh
+export CLAUDE_CODE_ENTRYPOINT=acme-agent   # any custom name
+```
+
+This is a workaround for an Anthropic-side bug, not an Anthropic-confirmed
+fix: it only changes how usage is attributed (custom labels are the same
+mechanism official surfaces like the VS Code extension use). It is opt-in —
+no launch is labeled unless `CPROXY_ENTRYPOINT` is set — so there is nothing
+to undo once the metering is fixed upstream.
+
 ## Hosting a shared cproxy
 
 Run one `cproxy serve` that holds the pool, and hand each person (or
@@ -328,10 +369,16 @@ claude
 ```
 
 Also set `export CLAUDE_CODE_PROMPT_CACHE_TTL=1h` to keep the 1-hour prompt
-cache; see [Prompt cache TTL](#prompt-cache-ttl).
+cache; see [Prompt cache TTL](#prompt-cache-ttl). And set
+`export CLAUDE_CODE_ENTRYPOINT=acme-agent` (any custom name) so headless use
+is not charged the `sdk-*` rate; see
+[The 5-hour meter and the entrypoint label](#the-5-hour-meter-and-the-entrypoint-label).
+This one has to be the environment variable, not the settings `env` block:
+cproxy is not launching claude there, and claude applies that block only to
+processes it spawns.
 
 If the cproxy shim is installed on that machine it sees `ANTHROPIC_BASE_URL`
-and stays out of the way. In Amp, set those two variables (the token as a
+and stays out of the way. In Amp, set those variables (the token as a
 secret) in your personal or project env instead of `CPROXY_TOKEN_*`.
 
 ### On the server

internal/launch/launch.go

@@ -23,27 +23,46 @@ var strippedEnv = []string{
 // although every pool account is a subscription.
 const promptCacheTTLEnv = "CLAUDE_CODE_PROMPT_CACHE_TTL"
 
+// Headless Claude Code (claude -p, the Agent SDK) labels its requests
+// sdk-cli or sdk-ts, and Anthropic's plan meters currently charge those
+// labels roughly 1.7x-2.9x more of the 5-hour window per token than the
+// same tokens under any other label (anthropics/claude-code#97074,
+// pingdotgg/t3code#24649). A custom label sidesteps the weighting — the
+// same workaround T3 Code and Paseo ship — and $CPROXY_ENTRYPOINT opts a
+// launch into it. The name must be custom: headless claude rewrites the
+// literal "cli" (the interactive TUI's default) to sdk-cli.
+const (
+	entrypointEnv       = "CLAUDE_CODE_ENTRYPOINT"
+	entrypointLabelFlag = "CPROXY_ENTRYPOINT"
+)
+
 // BuildChildEnv returns environ rewritten so the child talks to cproxy: the
 // base URL and auth token point at the local proxy, competing credentials
 // are removed, and every CPROXY_* variable (which may hold secrets) is
 // stripped. The prompt cache TTL defaults to 1h, as it would for a signed-in
-// subscriber, unless the environment already sets it.
+// subscriber, unless the environment already sets it, and the entrypoint
+// label is picked as entrypointFor describes.
 func BuildChildEnv(environ []string, baseURL, sessionToken string) []string {
+	entrypoint, setEntrypoint := entrypointFor(environ)
 	out := make([]string, 0, len(environ)+3)
 	hasTTL := false
 	for _, kv := range environ {
 		k, _, ok := strings.Cut(kv, "=")
 		if !ok {
 			continue
 		}
-		if slices.Contains(strippedEnv, k) || strings.HasPrefix(k, "CPROXY_") {
+		if slices.Contains(strippedEnv, k) || strings.HasPrefix(k, "CPROXY_") ||
+			(k == entrypointEnv && setEntrypoint) {
 			continue
 		}
 		if k == promptCacheTTLEnv {
 			hasTTL = true
 		}
 		out = append(out, kv)
 	}
+	if setEntrypoint {
+		out = append(out, entrypointEnv+"="+entrypoint)
+	}
 	if !hasTTL {
 		out = append(out, promptCacheTTLEnv+"=1h")
 	}
@@ -53,3 +72,45 @@ func BuildChildEnv(environ []string, baseURL, sessionToken string) []string {
 	)
 	return out
 }
+
+// entrypointFor picks the CLAUDE_CODE_ENTRYPOINT the child runs with. The
+// second return is false when the variable should be left exactly as the
+// environment has it, including absent — normal behaviour. That is the case
+// for $CPROXY_ENTRYPOINT unset, off, 0, or naming a label that cannot work
+// (cli, which headless claude rewrites to sdk-cli, and the sdk-* spellings).
+// Any other value names the label outright, replacing whatever the
+// environment has.
+func entrypointFor(environ []string) (string, bool) {
+	label, ok := envValue(environ, entrypointLabelFlag)
+	if !ok {
+		return "", false
+	}
+	switch strings.ToLower(strings.TrimSpace(label)) {
+	case "off", "0":
+		return "", false
+	}
+	if !usableEntrypoint(label) {
+		return "", false
+	}
+	return strings.TrimSpace(label), true
+}
+
+// usableEntrypoint reports whether value can serve as the label: the sdk-*
+// values are the over-charged category, and headless claude rewrites the
+// literal cli to sdk-cli, so those spellings are rejected; any other
+// non-empty value works.
+func usableEntrypoint(v string) bool {
+	v = strings.TrimSpace(v)
+	return v != "" && v != "cli" && !strings.HasPrefix(v, "sdk-")
+}
+
+// envValue returns the value of name in environ; empty values count as
+// unset.
+func envValue(environ []string, name string) (string, bool) {
+	for _, kv := range environ {
+		if k, v, ok := strings.Cut(kv, "="); ok && k == name && v != "" {
+			return v, true
+		}
+	}
+	return "", false
+}

internal/launch/launch_test.go

@@ -107,3 +107,46 @@ func TestBuildChildEnvKeepsPromptCacheTTL(t *testing.T) {
 		t.Fatalf("prompt cache TTL set %d times, want 1", n)
 	}
 }
+
+func TestBuildChildEnvEntrypoint(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		env  []string
+		want []string // CLAUDE_CODE_ENTRYPOINT values the child env must hold
+	}{
+		{name: "no flag sets nothing", env: nil, want: nil},
+		{name: "no flag leaves inherited custom alone", env: []string{"CLAUDE_CODE_ENTRYPOINT=my-tool"}, want: []string{"my-tool"}},
+		{name: "no flag leaves inherited sdk-cli alone", env: []string{"CLAUDE_CODE_ENTRYPOINT=sdk-cli"}, want: []string{"sdk-cli"}},
+		{name: "no flag leaves inherited sdk-ts alone", env: []string{"CLAUDE_CODE_ENTRYPOINT=sdk-ts"}, want: []string{"sdk-ts"}},
+		{name: "no flag leaves inherited cli alone", env: []string{"CLAUDE_CODE_ENTRYPOINT=cli"}, want: []string{"cli"}},
+		{name: "no flag leaves inherited empty alone", env: []string{"CLAUDE_CODE_ENTRYPOINT="}, want: []string{""}},
+		{name: "flag names label", env: []string{"CPROXY_ENTRYPOINT=paseo"}, want: []string{"paseo"}},
+		{name: "flag trims label", env: []string{"CPROXY_ENTRYPOINT=  paseo  "}, want: []string{"paseo"}},
+		{name: "flag replaces inherited sdk-ts", env: []string{"CPROXY_ENTRYPOINT=paseo", "CLAUDE_CODE_ENTRYPOINT=sdk-ts"}, want: []string{"paseo"}},
+		{name: "flag replaces inherited custom", env: []string{"CPROXY_ENTRYPOINT=paseo", "CLAUDE_CODE_ENTRYPOINT=my-tool"}, want: []string{"paseo"}},
+		{name: "flag cli touches nothing", env: []string{"CPROXY_ENTRYPOINT=cli"}, want: nil},
+		{name: "flag cli leaves inherited alone", env: []string{"CPROXY_ENTRYPOINT=cli", "CLAUDE_CODE_ENTRYPOINT=cli"}, want: []string{"cli"}},
+		{name: "flag sdk-ts touches nothing", env: []string{"CPROXY_ENTRYPOINT=sdk-ts"}, want: nil},
+		{name: "flag off sets nothing", env: []string{"CPROXY_ENTRYPOINT=off"}, want: nil},
+		{name: "flag off leaves inherited alone", env: []string{"CPROXY_ENTRYPOINT=off", "CLAUDE_CODE_ENTRYPOINT=sdk-cli"}, want: []string{"sdk-cli"}},
+		{name: "flag zero sets nothing", env: []string{"CPROXY_ENTRYPOINT=0"}, want: nil},
+		{name: "flag empty sets nothing", env: []string{"CPROXY_ENTRYPOINT="}, want: nil},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := entrypointValues(BuildChildEnv(tc.env, "http://127.0.0.1:4123", "cp_sess"))
+			if !slices.Equal(got, tc.want) {
+				t.Fatalf("CLAUDE_CODE_ENTRYPOINT = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}
+
+func entrypointValues(env []string) []string {
+	var got []string
+	for _, kv := range env {
+		if k, v, ok := cut(kv); ok && k == "CLAUDE_CODE_ENTRYPOINT" {
+			got = append(got, v)
+		}
+	}
+	return got
+}