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fix(codex): suppress inherited forked subagent usage #521

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Merged
junhoyeo merged 1 commit into from
May 10, 2026
Merged

fix(codex): suppress inherited forked subagent usage #521

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2 changes: 1 addition & 1 deletion crates/tokscale-core/src/message_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ use std::io::{BufReader, BufWriter, Read, Seek, SeekFrom, Write};
use std::path::{Path, PathBuf};
use std::time::UNIX_EPOCH;

const CACHE_SCHEMA_VERSION: u32 = 11;
const CACHE_SCHEMA_VERSION: u32 = 12;
const CACHE_FILENAME: &str = "source-message-cache.bin";
const CACHE_LOCK_FILENAME: &str = "source-message-cache.lock";
const MAX_CACHE_FILE_BYTES: u64 = 256 * 1024 * 1024;
Expand Down
154 changes: 154 additions & 0 deletions crates/tokscale-core/src/sessions/codex.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@ pub struct CodexTokenUsage {
pub cached_input_tokens: Option<i64>,
pub cache_read_input_tokens: Option<i64>,
pub reasoning_output_tokens: Option<i64>,
pub total_tokens: Option<i64>,
}

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
Expand Down Expand Up @@ -160,6 +161,9 @@ pub(crate) struct CodexParseState {
pub session_agent: Option<String>,
pub session_workspace_key: Option<String>,
pub session_workspace_label: Option<String>,
pub forked_child_waiting_for_turn_context: bool,
pub forked_child_inherited_baseline: Option<CodexTotals>,
pub forked_child_inherited_reported_total: Option<i64>,
}

#[derive(Debug, Clone)]
Expand Down Expand Up @@ -261,6 +265,21 @@ fn parse_codex_reader<R: BufRead>(
};
let event_model = payload_model.clone().or(info_model.clone());

if state.forked_child_waiting_for_turn_context {
if entry.entry_type == "turn_context" {
state.forked_child_waiting_for_turn_context = false;
state.current_model = payload_model.clone();
handled = true;
} else {
if is_token_count {
if let Some(info) = payload.info.as_ref() {
remember_forked_child_inherited_baseline(&mut state, info);
}
}
continue;
}
}

if !pending_model_messages.is_empty()
&& event_model.is_none()
&& !is_token_count
Expand All @@ -283,6 +302,9 @@ fn parse_codex_reader<R: BufRead>(
}
if let Some(ref forked_from_id) = payload.forked_from_id {
state.session_forked_from_id = Some(forked_from_id.clone());
state.forked_child_waiting_for_turn_context = true;
state.forked_child_inherited_baseline = None;
state.forked_child_inherited_reported_total = None;
}
if let Some(ref provider) = payload.model_provider {
state.session_provider = Some(provider.clone());
Expand Down Expand Up @@ -337,6 +359,21 @@ fn parse_codex_reader<R: BufRead>(
let total_usage = info.total_token_usage.as_ref().map(CodexTotals::from_usage);
let last_usage = info.last_token_usage.as_ref().map(CodexTotals::from_usage);

if forked_child_matches_inherited_baseline(
&state,
info.total_token_usage.as_ref(),
total_usage,
) {
if let Some(total) = total_usage {
state.previous_totals = Some(total);
}
state.forked_child_inherited_baseline = None;
state.forked_child_inherited_reported_total = None;
continue;
}
state.forked_child_inherited_baseline = None;
state.forked_child_inherited_reported_total = None;

let (tokens, next_totals) =
match (total_usage, last_usage, state.previous_totals) {
// Both present with previous baseline (standard path)
Expand Down Expand Up @@ -446,6 +483,13 @@ fn parse_codex_reader<R: BufRead>(
continue;
}

if state.forked_child_waiting_for_turn_context {
let mut json_probe = trimmed.as_bytes().to_vec();
if simd_json::from_slice::<Value>(&mut json_probe).is_ok() {
continue;
}
}

let headless_message = parse_codex_headless_line(
trimmed,
session_id,
Expand Down Expand Up @@ -590,6 +634,41 @@ pub fn parse_codex_file(path: &Path) -> Vec<UnifiedMessage> {
parsed.messages
}

fn reported_total_tokens(usage: &CodexTokenUsage) -> Option<i64> {
usage.total_tokens.filter(|total| *total >= 0)
}

fn remember_forked_child_inherited_baseline(state: &mut CodexParseState, info: &CodexInfo) {
let Some(total_usage) = info.total_token_usage.as_ref() else {
return;
};

let totals = CodexTotals::from_usage(total_usage);
state.previous_totals = Some(totals);
state.forked_child_inherited_baseline = Some(totals);
state.forked_child_inherited_reported_total = reported_total_tokens(total_usage);
}

fn forked_child_matches_inherited_baseline(
state: &CodexParseState,
total_usage: Option<&CodexTokenUsage>,
totals: Option<CodexTotals>,
) -> bool {
if let (Some(usage), Some(baseline)) =
(total_usage, state.forked_child_inherited_reported_total)
{
if reported_total_tokens(usage) == Some(baseline) {
return true;
}
}

if let (Some(totals), Some(baseline)) = (totals, state.forked_child_inherited_baseline) {
return totals == baseline;
}

false
}

pub(crate) fn parse_codex_file_incremental(
path: &Path,
start_offset: u64,
Expand Down Expand Up @@ -1392,6 +1471,80 @@ mod tests {
assert!(messages[0].dedup_key.is_some());
}

#[test]
fn test_forked_child_ignores_inherited_records_before_turn_context() {
let file = create_test_file(concat!(
r#"{"timestamp":"2026-05-05T21:51:57.991Z","type":"session_meta","payload":{"id":"child-session","forked_from_id":"parent-session","source":{"subagent":{"thread_spawn":{"parent_thread_id":"parent-session","depth":1}}},"model_provider":"openai","agent_nickname":"worker","cwd":"/repo-child"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:57.992Z","type":"session_meta","payload":{"id":"parent-session","source":"interactive","model_provider":"azure","agent_nickname":"parent","cwd":"/repo-parent"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:57.993Z","type":"event_msg","payload":{"type":"user_message","message":"parent prompt copied into child log"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:57.994Z","type":"event_msg","payload":{"type":"token_count","info":{"total_token_usage":{"input_tokens":116000,"cached_input_tokens":114000,"output_tokens":1000,"total_tokens":117000},"last_token_usage":{"input_tokens":73000,"cached_input_tokens":72000,"output_tokens":500,"total_tokens":73500}}}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:58.947Z","type":"turn_context","payload":{"model":"gpt-5.5","cwd":"/repo-child"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:58.948Z","type":"event_msg","payload":{"type":"token_count","info":{"total_token_usage":{"input_tokens":116000,"cached_input_tokens":114000,"output_tokens":1000,"total_tokens":117000},"last_token_usage":{"input_tokens":73000,"cached_input_tokens":72000,"output_tokens":500,"total_tokens":73500}}}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:59.253Z","type":"event_msg","payload":{"type":"token_count","info":{"total_token_usage":{"input_tokens":117500,"cached_input_tokens":115000,"output_tokens":1200,"reasoning_output_tokens":50,"total_tokens":118700},"last_token_usage":{"input_tokens":1500,"cached_input_tokens":1000,"output_tokens":200,"reasoning_output_tokens":50,"total_tokens":1700}}}}"#,
"\n"
));

let messages = parse_codex_file(file.path());

assert_eq!(messages.len(), 1);
assert_eq!(messages[0].model_id, "gpt-5.5");
assert_eq!(messages[0].provider_id, "openai");
assert_eq!(messages[0].agent.as_deref(), Some("worker"));
assert_eq!(messages[0].workspace_key.as_deref(), Some("/repo-child"));
assert_eq!(messages[0].tokens.input, 500);
assert_eq!(messages[0].tokens.cache_read, 1000);
assert_eq!(messages[0].tokens.output, 200);
assert_eq!(messages[0].tokens.reasoning, 50);
}

#[test]
fn test_forked_child_incremental_state_skips_inherited_prefix() {
let file = create_test_file(concat!(
r#"{"timestamp":"2026-05-05T21:51:57.991Z","type":"session_meta","payload":{"id":"child-session","forked_from_id":"parent-session","source":{"subagent":{"thread_spawn":{"parent_thread_id":"parent-session","depth":1}}},"model_provider":"openai","agent_nickname":"worker","cwd":"/repo-child"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:57.992Z","type":"session_meta","payload":{"id":"parent-session","source":"interactive","model_provider":"azure","agent_nickname":"parent","cwd":"/repo-parent"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:57.994Z","type":"event_msg","payload":{"type":"token_count","info":{"total_token_usage":{"input_tokens":116000,"cached_input_tokens":114000,"output_tokens":1000,"total_tokens":117000},"last_token_usage":{"input_tokens":73000,"cached_input_tokens":72000,"output_tokens":500,"total_tokens":73500}}}}"#,
"\n"
));
let prefix_size = file.as_file().metadata().unwrap().len();
let prefix = parse_codex_file_incremental(file.path(), 0, CodexParseState::default());

assert!(prefix.parse_succeeded);
assert!(!prefix.unresolved_model_events);
assert!(prefix.messages.is_empty());

let appended = concat!(
r#"{"timestamp":"2026-05-05T21:51:58.947Z","type":"turn_context","payload":{"model":"gpt-5.5","cwd":"/repo-child"}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:58.948Z","type":"event_msg","payload":{"type":"token_count","info":{"total_token_usage":{"input_tokens":116000,"cached_input_tokens":114000,"output_tokens":1000,"total_tokens":117000},"last_token_usage":{"input_tokens":73000,"cached_input_tokens":72000,"output_tokens":500,"total_tokens":73500}}}}"#,
"\n",
r#"{"timestamp":"2026-05-05T21:51:59.253Z","type":"event_msg","payload":{"type":"token_count","info":{"total_token_usage":{"input_tokens":117500,"cached_input_tokens":115000,"output_tokens":1200,"reasoning_output_tokens":50,"total_tokens":118700},"last_token_usage":{"input_tokens":1500,"cached_input_tokens":1000,"output_tokens":200,"reasoning_output_tokens":50,"total_tokens":1700}}}}"#,
"\n"
);
let mut reopened = file.reopen().unwrap();
reopened.seek(SeekFrom::End(0)).unwrap();
reopened.write_all(appended.as_bytes()).unwrap();
reopened.flush().unwrap();

let incremental =
parse_codex_file_incremental(file.path(), prefix_size, prefix.state.clone());
let full = parse_codex_file(file.path());

assert_eq!(incremental.messages, full);
assert_eq!(incremental.messages.len(), 1);
assert_eq!(incremental.messages[0].tokens.input, 500);
assert_eq!(incremental.messages[0].tokens.cache_read, 1000);
assert_eq!(incremental.messages[0].tokens.output, 200);
assert_eq!(incremental.messages[0].tokens.reasoning, 50);
}

#[test]
fn test_session_meta_cwd_sets_workspace_metadata() {
let line1 = r#"{"timestamp":"2026-01-01T00:00:00Z","type":"session_meta","payload":{"source":"interactive","cwd":"/Users/alice/demo-repo"}}"#;
Expand Down Expand Up @@ -1490,6 +1643,7 @@ mod tests {
cached_input_tokens: Some(10),
cache_read_input_tokens: Some(20),
reasoning_output_tokens: Some(5),
total_tokens: None,
};
let totals = CodexTotals::from_usage(&usage);
assert_eq!(totals.cached, 20);
Expand Down
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