polyipseity Progress bar debug with JSONL tick dumps
Emit one JSONL line per tick (~50 ms) with the full state of every bar slot.
Quick start
MEDIAPM_PROGRESS_DEBUG=auto cargo run ...
Creates progress-debug-<PID>.jsonl in CWD. Monitor live:
tail -f progress-debug-*.jsonl | jq .
Env var values
| Value | Behavior |
|---|---|
auto or empty |
Writes to progress-debug-<PID>.jsonl in CWD |
/path/to/file.jsonl |
Writes to the specified path (creates/overwrites) |
| unset | No debug output (default) |
JSONL schema
Each line is a JSON object with these fields:
Top-level
| Field | Type | Description |
|---|---|---|
type |
string | "tick" (discriminant, future: "attach", "finish") |
tick |
int | Monotonic tick counter (starts at 0) |
elapsed_secs |
float | Seconds since sink creation |
bars |
array | Per-slot bar states (see below) |
Bar slot (bars[])
| Field | Type | Description |
|---|---|---|
slot |
int | Slot index in renderer grid |
bound |
bool | Whether a bar is attached to this slot |
label |
string | Bar label (always present) |
prefix |
string | Bar prefix (always present) |
position |
int | Work completed |
total |
int | Total work (0 = indeterminate) |
status |
string | e.g. "Active", "Finished", "Abandoned" |
elapsed_secs |
float | Seconds since handle creation |
rate_bytes_per_sec |
float | EMA-smoothed rate (0.0 when inactive) |
eta_secs |
float or null | Estimated seconds remaining (null when unknown) |
message |
string | Custom message (empty when none) |
dirty |
bool | Whether source was dirty this tick |
Usage patterns
Filter by bar slot:
tail -f debug.jsonl | jq 'select(.bars[0].bound) | .bars[0]'
Watch position progression:
tail -f debug.jsonl | jq -r '[.tick, .bars[] | select(.bound) | "\(.slot): \(.position)/\(.total)"] | @tsv'
Detect stuck bars (position unchanged for N ticks):
tail -f debug.jsonl | jq -r '[.tick, .bars[] | select(.bound) | .position] | @tsv'
Filter by status:
jq -c 'select(.bars[] | .status != "Active")' progress-debug-*.jsonl
Notes
- Debug output goes to a file, not stderr — it never competes with terminal rendering.
- The ticker thread races with manual
group.tick()calls, so lines may arrive out of phase with wall-clock ticks. - Stderr output is intentionally unsupported to avoid interfering with the progress bar renderer.