diff --git a/packages/ludic.telemetry/README.md b/packages/ludic.telemetry/README.md
index 4c36483c..55320059 100644
--- a/packages/ludic.telemetry/README.md
+++ b/packages/ludic.telemetry/README.md
@@ -23,22 +23,31 @@ machine. With no salt, or where it cannot be read within ten seconds, it is rand
 lives in the game's id file as `{"id": ...}`; any other key the game keeps there is left alone.
 An event queued before the id is known carries a mark that the batch replaces.
 
+## Nothing is made per event
+
+Ludic gives nothing back, so an event is never a tree of values or a string of its own. Its
+properties are written as JSON into a kept buffer (`telemetry_props`), the line into another, and
+the line's bytes into one ring made at the start (`ring_bytes`, at most `queue_max` lines): past
+either, the oldest are overwritten. A batch and the queue file are written into a third kept buffer
+and go out as bytes (`Http.body_bytes`, `Fs.write_bytes`). An event's time is worked out from the
+clock's seconds, not formatted. `tests/ring_test` holds it: ten thousand events past the cap, 0 bytes.
+
 ## Config and ports (`bind`)
 
 ```ludic
 property TelemetryConfig {
   host, key, path ("/batch/"), lib        # an empty host or key sends nothing, ever
   queue_file, id_file, id_salt, id_scratch
-  flush_ms (30000), flush_at (50), batch (200), queue_max (5000), backoff_max (6), save_ms (5000)
+  flush_ms (30000), flush_at (50), batch (200), queue_max (5000), ring_bytes (1 MB), backoff_max (6), save_ms (5000)
 }
 port TelemetryWorld {
   can_send: fn() -> bool     # may this run send at all - a test, a headless run (unbound: yes)
   enabled: fn() -> bool      # the player's switch (unbound: on)
   now_ms: fn() -> int        # a clock (unbound: the wall clock, by the second)
-  stamp: fn() -> string      # an event's ISO time (unbound: now)
+  clock_s: fn() -> int       # the wall clock in seconds since 1970, for an event's time (unbound: now)
 }
 port TelemetryTransport {    # unbound: Http
-  send: fn(string, string) -> int   # url, body -> a handle, < 0 if it could not start
+  send: fn(string, []byte, int) -> int   # url, body, its length -> a handle, < 0 if it could not start
   poll: fn(int) -> int              # -1 pending, 0 failed, 1 taken
   drop: fn(int) -> void             # abandon one
 }
@@ -56,6 +65,7 @@ bind TelemetryWorld { can_send: fn my_can_send, enabled: fn my_switch }
 | --- | --- |
 | `telemetry_config(c)` | before the start |
 | `telemetry_start()` | once, at boot: the id, a session, and the queue an earlier start left (or none, if off) |
+| `telemetry_props()`, `telemetry_str(p, k, s)`, `telemetry_int(p, k, n)`, `telemetry_bool(p, k, b)` | the next event's properties, written into a buffer the state keeps |
 | `telemetry_event(name, props)` | queue one (props may be null); nothing is kept while off or while the run may not send |
 | `telemetry_tick()` | every frame: the machine id's child, a batch when due (every `flush_ms`, or at `flush_at` events), its answer, the backoff, the queue on disk every `save_ms`; off forgets |
 | `telemetry_save()` | the queue on disk now (a quit, a child about to start) |
diff --git a/packages/ludic.telemetry/facts.ludic b/packages/ludic.telemetry/facts.ludic
new file mode 100644
index 00000000..a56dfe01
--- /dev/null
+++ b/packages/ludic.telemetry/facts.ludic
@@ -0,0 +1,16 @@
+# facts.ludic - a fact's record reused (the ludic.wildlife idiom): a batch sent or failed is a fact
+# a fact record no drain holds any more, made (and kept) only when every one is held
+function telemetry__fact_record(telemetry_st: mut TelemetryState) -> TelemetryFact {
+  if telemetry_st.telemetry__fnext[0] >= len(telemetry_st.telemetry__ffree) {
+    q_unheld(telemetry_st.telemetry__facts, telemetry_st.telemetry__fpool, telemetry_st.telemetry__ffree)
+    telemetry_st.telemetry__fnext[0] = 0
+  }
+  if telemetry_st.telemetry__fnext[0] < len(telemetry_st.telemetry__ffree) {
+    let f = telemetry_st.telemetry__ffree[telemetry_st.telemetry__fnext[0]]
+    telemetry_st.telemetry__fnext[0] += 1
+    return f
+  }
+  let f = new TelemetryFact
+  push(telemetry_st.telemetry__fpool, f)
+  return f
+}
diff --git a/packages/ludic.telemetry/index.ludic b/packages/ludic.telemetry/index.ludic
index b9b4956e..8539fd02 100644
--- a/packages/ludic.telemetry/index.ludic
+++ b/packages/ludic.telemetry/index.ludic
@@ -4,8 +4,14 @@ module ludic_telemetry uses ludic_base
 numbers float
 import "ludic.base"
 import "state.ludic"
+import "facts.ludic"
 import "ports.ludic"
+import "props.ludic"
+import "props_nest.ludic"
+import "stamp.ludic"
+import "ring.ludic"
 import "queue.ludic"
+import "load.ludic"
 import "send.ludic"
 import "ident.ludic"
 import "queries.ludic"
diff --git a/packages/ludic.telemetry/load.ludic b/packages/ludic.telemetry/load.ludic
new file mode 100644
index 00000000..bb1415ee
--- /dev/null
+++ b/packages/ludic.telemetry/load.ludic
@@ -0,0 +1,46 @@
+# load.ludic - the unsent lines a start finds on disk, read once into the ring with their marks found
+function telemetry__queue_load(telemetry_st: mut TelemetryState) -> void {
+  let f = telemetry__conf(telemetry_st).queue_file
+  if len(f) == 0 { return }
+  let b = Fs.read_bytes(f)
+  if b == null { return }
+  var start = 0
+  for i in 0 .. len(b) + 1 {
+    if i == len(b) or b[i] == 10 {
+      if i - start > 2 { tq_load_line(telemetry_st, b, start, i - start) }
+      start = i + 1
+    }
+  }
+  telemetry_st.telemetry__dirty = false
+}
+# a line read back (once, at a start): through the kept line buffer, its mark found again
+function tq_load_line(telemetry_st: mut TelemetryState, b: []byte, at: int, n: int) -> void {
+  let sb = telemetry_st.telemetry__line
+  sb_clear(sb)
+  for i in 0 .. n { sb_byte(sb, b[at + i]) }
+  if tj_full(sb) { return }
+  tr_add(telemetry_st, sb.b, n, tq_find_mark(sb.b, n))
+}
+function tq_find_mark(b: []byte, n: int) -> int {
+  let m: string = TELEMETRY_MARK
+  let k = len(m)
+  for i in 0 .. n - k + 1 {
+    var same = true
+    for j in 0 .. k { if same and b[i + j] != m[j] { same = false } }
+    if same { return i }
+  }
+  return -1
+}
+
+function telemetry__read_obj(path: string) -> Val {
+  if len(path) == 0 { return null }
+  let s = Fs.read_text(path)
+  if s == null { return null }
+  let v = Json.parse(s)
+  if v == null { return null }
+  if Value.kind(v) != 6 {
+    Json.free(v)
+    return null
+  }
+  return v
+}
diff --git a/packages/ludic.telemetry/ports.ludic b/packages/ludic.telemetry/ports.ludic
index e8d2cb6c..96c80436 100644
--- a/packages/ludic.telemetry/ports.ludic
+++ b/packages/ludic.telemetry/ports.ludic
@@ -1,5 +1,8 @@
 # ports.ludic - the config, and what the ports answer when the game leaves them unbound
-export function telemetry_config(telemetry_st: mut TelemetryState, c: TelemetryConfig) -> void { telemetry_st.telemetry__cfg = c }
+export function telemetry_config(telemetry_st: mut TelemetryState, c: TelemetryConfig) -> void {
+  telemetry_st.telemetry__cfg = c
+  telemetry_st.telemetry__url = c.host + c.path
+}
 
 function telemetry__conf(telemetry_st: TelemetryState) -> TelemetryConfig {
   return telemetry_st.telemetry__cfg
@@ -7,7 +10,7 @@ function telemetry__conf(telemetry_st: TelemetryState) -> TelemetryConfig {
 
 function telemetry__yes() -> bool { return true }
 function telemetry__wall_ms(telemetry_st: TelemetryState) -> int { return (Time.now() - telemetry_st.telemetry__t0) * 1000 }
-function telemetry__wall_stamp() -> string { return DateTime.format(Time.now(), "YYYY-MM-DDTHH:mm:ssZ") }
+function telemetry__wall_s() -> int { return Time.now() }
 
 function telemetry__can_send(telemetry_st: TelemetryState) -> bool {
   let c = telemetry__conf(telemetry_st)
@@ -17,13 +20,12 @@ function telemetry__can_send(telemetry_st: TelemetryState) -> bool {
 
 function telemetry__enabled() -> bool { return TelemetryWorld.enabled() }
 function telemetry__now() -> int { return TelemetryWorld.now_ms() }
-function telemetry__stamp() -> string { return TelemetryWorld.stamp() }
 
-function telemetry__http_send(url: string, body: string) -> int {
+function telemetry__http_send(url: string, body: []byte, n: int) -> int {
   let h = Http.open("POST", url)
   if h < 0 { return h }
   Http.set(h, "Content-Type", "application/json")
-  Http.body(h, body)
+  Http.body_bytes(h, data_of(body), n)
   Http.send(h)
   return h
 }
@@ -39,7 +41,7 @@ function telemetry__http_poll(h: int) -> int {
 
 function telemetry__http_drop(h: int) -> void { Http.free(h) }
 
-function telemetry__send(telemetry_st: TelemetryState, body: string) -> int { return TelemetryTransport.send(telemetry__conf(telemetry_st).host + telemetry__conf(telemetry_st).path, body) }
+function telemetry__send(telemetry_st: TelemetryState, body: []byte, n: int) -> int { return TelemetryTransport.send(telemetry_st.telemetry__url, body, n) }
 function telemetry__poll(h: int) -> int { return TelemetryTransport.poll(h) }
 
 # a request abandoned (the player said no)
diff --git a/packages/ludic.telemetry/props.ludic b/packages/ludic.telemetry/props.ludic
new file mode 100644
index 00000000..19c4599e
--- /dev/null
+++ b/packages/ludic.telemetry/props.ludic
@@ -0,0 +1,72 @@
+# props.ludic - an event's properties written as JSON into a buffer the state keeps, never a tree of
+# values: a game says an event often, and Ludic gives nothing back
+export const TELEMETRY_LINE: int = 2048   # the longest line an event may be; a longer one is dropped
+
+export property TelemetryProps {
+  sb: StrBuf = null
+  n: int = 0                  # properties written at the top
+  lv: []int = null            # inside an object or a list: how many written at each level
+  d: int = 0                  # how deep
+}
+
+# the writer, emptied, for the next event's properties
+export function telemetry_props(telemetry_st: mut TelemetryState) -> TelemetryProps {
+  let p = telemetry_st.telemetry__props
+  sb_clear(p.sb)
+  p.n = 0
+  p.d = 0
+  return p
+}
+export function telemetry_str(p: TelemetryProps, k: string, s: string) -> void {
+  tp_key(p, k)
+  tj_str(p.sb, s)
+}
+export function telemetry_int(p: TelemetryProps, k: string, v: int) -> void {
+  tp_key(p, k)
+  sb_int(p.sb, v)
+}
+export function telemetry_bool(p: TelemetryProps, k: string, b: bool) -> void {
+  tp_key(p, k)
+  if b { sb_add(p.sb, "true") } else { sb_add(p.sb, "false") }
+}
+function tp_key(p: TelemetryProps, k: string) -> void {
+  tp_next(p)
+  tj_str(p.sb, k)
+  sb_byte(p.sb, 58)
+}
+# a comma before all but the first at this level, and the count kept
+function tp_next(p: TelemetryProps) -> void {
+  if p.d == 0 {
+    if p.n > 0 { sb_byte(p.sb, 44) }
+    p.n += 1
+    return
+  }
+  if p.lv[p.d] > 0 { sb_byte(p.sb, 44) }
+  p.lv[p.d] += 1
+}
+
+# a JSON string: quoted, a quote or a backslash escaped, a control byte as \u00XX
+function tj_str(sb: StrBuf, s: string) -> void {
+  sb_byte(sb, 34)
+  if s != null {
+    let sp: string = s
+    for i in 0 .. len(sp) {
+      let c = sp[i]
+      if c == 34 or c == 92 {
+        sb_byte(sb, 92)
+        sb_byte(sb, c)
+      } else if c < 32 {
+        sb_add(sb, "\\u00")
+        sb_byte(sb, tj_hex(c / 16))
+        sb_byte(sb, tj_hex(c % 16))
+      } else { sb_byte(sb, c) }
+    }
+  }
+  sb_byte(sb, 34)
+}
+function tj_hex(v: int) -> int {
+  if v < 10 { return 48 + v }
+  return 87 + v
+}
+# a line that reached the end of its buffer was cut: it is dropped rather than sent broken
+function tj_full(sb: StrBuf) -> bool { return sb_len(sb) >= len(sb.b) - 1 }
diff --git a/packages/ludic.telemetry/props_nest.ludic b/packages/ludic.telemetry/props_nest.ludic
new file mode 100644
index 00000000..bb539a4b
--- /dev/null
+++ b/packages/ludic.telemetry/props_nest.ludic
@@ -0,0 +1,43 @@
+# props_nest.ludic - an object or a list inside an event's properties ($set, a photograph's subjects, the
+# party's names), written into the same kept buffer; and a signature of what was written, to tell a
+# change without keeping a copy
+export function telemetry_obj(p: TelemetryProps, k: string) -> void { tn_open(p, k, 123) }
+export function telemetry_list(p: TelemetryProps, k: string) -> void { tn_open(p, k, 91) }
+export function telemetry_obj_end(p: TelemetryProps) -> void { tn_close(p, 125) }
+export function telemetry_list_end(p: TelemetryProps) -> void { tn_close(p, 93) }
+function tn_open(p: TelemetryProps, k: string, c: int) -> void {
+  tp_key(p, k)
+  sb_byte(p.sb, c)
+  if p.lv == null { p.lv = words(8) }
+  if p.d < len(p.lv) - 1 { p.d += 1 }
+  p.lv[p.d] = 0
+}
+function tn_close(p: TelemetryProps, c: int) -> void {
+  sb_byte(p.sb, c)
+  if p.d > 0 { p.d -= 1 }
+}
+# a string in the list being written
+export function telemetry_item_str(p: TelemetryProps, s: string) -> void {
+  tp_next(p)
+  tj_str(p.sb, s)
+}
+# a string item made of numbers the caller writes itself (sb_int, sb_byte - no quote or backslash)
+export function telemetry_item_open(p: TelemetryProps) -> StrBuf {
+  tp_next(p)
+  sb_byte(p.sb, 34)
+  return p.sb
+}
+export function telemetry_item_close(p: TelemetryProps) -> void { sb_byte(p.sb, 34) }
+# the same for a named string property; closed with telemetry_item_close
+export function telemetry_str_open(p: TelemetryProps, k: string) -> StrBuf {
+  tp_key(p, k)
+  sb_byte(p.sb, 34)
+  return p.sb
+}
+
+# a number standing for what has been written: equal when the bytes are (FNV-1a, 31 bits)
+export function telemetry_props_sig(p: TelemetryProps) -> int {
+  var h = 2166136261 & 2147483647
+  for i in 0 .. sb_len(p.sb) { h = ((h ^ p.sb.b[i]) * 16777619) & 2147483647 }
+  return h
+}
diff --git a/packages/ludic.telemetry/queries.ludic b/packages/ludic.telemetry/queries.ludic
index 641ba8f9..46e9aa4b 100644
--- a/packages/ludic.telemetry/queries.ludic
+++ b/packages/ludic.telemetry/queries.ludic
@@ -7,13 +7,14 @@ export function telemetry_fails(telemetry_st: TelemetryState) -> int { return te
 export function telemetry_next_ms(telemetry_st: TelemetryState) -> int { return telemetry_st.telemetry__next_ms }
 export function telemetry_in_flight(telemetry_st: TelemetryState) -> bool { return telemetry_st.telemetry__h >= 0 }
 
-export function telemetry_queued(telemetry_st: TelemetryState) -> int {
-  if telemetry_st.telemetry__q == null { return 0 }
-  return len(telemetry_st.telemetry__q)
-}
+export function telemetry_queued(telemetry_st: TelemetryState) -> int { return telemetry_st.telemetry__n }
 
 # a queued line as it will be sent, player mark and all
-export function telemetry_line(telemetry_st: TelemetryState, i: int) -> string { return telemetry_st.telemetry__q[i] }
+export function telemetry_line(telemetry_st: TelemetryState, i: int) -> string {
+  let sb = sb_new(TELEMETRY_LINE)
+  tr_line_to(telemetry_st, i, sb, null)
+  return text_of(sb.b, sb_len(sb))
+}
 
 # back to before telemetry_start, ports and config kept (tests; a start after a failed boot)
 export function telemetry_reset(telemetry_st: mut TelemetryState) -> void {
@@ -21,7 +22,7 @@ export function telemetry_reset(telemetry_st: mut TelemetryState) -> void {
   telemetry_st.telemetry__ready = false
   telemetry_st.telemetry__id = ""
   telemetry_st.telemetry__session = ""
-  telemetry_st.telemetry__q = null
+  if telemetry_st.telemetry__ring != null { tr_clear(telemetry_st) }
   telemetry_st.telemetry__dirty = false
   telemetry_st.telemetry__sent_n = 0
   telemetry_st.telemetry__next_ms = 0
diff --git a/packages/ludic.telemetry/queue.ludic b/packages/ludic.telemetry/queue.ludic
index 893720d7..56a297c5 100644
--- a/packages/ludic.telemetry/queue.ludic
+++ b/packages/ludic.telemetry/queue.ludic
@@ -1,4 +1,4 @@
-# queue.ludic - a start, an event encoded once into a line, the queue on disk, and forgetting
+# queue.ludic - a start, an event written once into a line in the ring, the queue on disk, and forgetting
 # once, at boot: who this is (from the id file, or begun from the machine), a new session, and
 # whatever an earlier start left unsent - or nothing, if the player has it off
 export function telemetry_start(telemetry_st: mut TelemetryState) -> void {
@@ -6,7 +6,7 @@ export function telemetry_start(telemetry_st: mut TelemetryState) -> void {
   telemetry_st.telemetry__ready = true
   telemetry_st.telemetry__t0 = Time.now()
   telemetry_st.telemetry__session = telemetry_random_hex(telemetry_st, 16)
-  telemetry_st.telemetry__q = new []string
+  tr_init(telemetry_st)
   telemetry_st.telemetry__id = sv_str(telemetry__read_obj(telemetry__conf(telemetry_st).id_file), "id", "")
   if len(telemetry_st.telemetry__id) == 0 { telemetry__id_begin(telemetry_st) }
   if telemetry__enabled() { telemetry__queue_load(telemetry_st) } else { telemetry_forget(telemetry_st) }
@@ -15,87 +15,80 @@ export function telemetry_start(telemetry_st: mut TelemetryState) -> void {
 # may an event be kept right now?
 export function telemetry_on(telemetry_st: TelemetryState) -> bool { return telemetry_st.telemetry__ready and telemetry__enabled() and telemetry__can_send(telemetry_st) }
 
-# an event: the properties (null for none) with the session and the library added, and the player
-# as a mark put in when the batch goes, so an event queued before the id is known is not misfiled
-export function telemetry_event(telemetry_st: mut TelemetryState, name: string, props: Val) -> void {
+# an event: its properties (null for none) with the session and the library added, the player as a
+# mark put in when the batch goes, so an event queued before the id is known is not misfiled. The
+# line is written into a kept buffer and copied into the ring: nothing is made for it
+export function telemetry_event(telemetry_st: mut TelemetryState, name: string, props: TelemetryProps) -> void {
   if not telemetry_on(telemetry_st) { return }
-  var p = props
-  if p == null { p = Value.object() }
-  Value.put(p, "$session_id", Value.str(telemetry_st.telemetry__session))
-  if len(telemetry__conf(telemetry_st).lib) > 0 { Value.put(p, "$lib", Value.str(telemetry__conf(telemetry_st).lib)) }
-  let e = Value.object()
-  Value.put(e, "event", Value.str(name))
-  Value.put(e, "distinct_id", Value.str(TELEMETRY_MARK))
-  Value.put(e, "properties", p)
-  Value.put(e, "timestamp", Value.str(telemetry__stamp()))
-  push(telemetry_st.telemetry__q, Json.encode(e))
-  telemetry_st.telemetry__dirty = true
-  let c = telemetry__conf(telemetry_st)
-  if len(telemetry_st.telemetry__q) > c.queue_max + c.batch { telemetry__queue_drop(telemetry_st, len(telemetry_st.telemetry__q) - c.queue_max) }
+  let sb = telemetry_st.telemetry__line
+  sb_clear(sb)
+  sb_add(sb, "{\"event\":")
+  tj_str(sb, name)
+  sb_add(sb, ",\"distinct_id\":\"")
+  let mk = sb_len(sb)
+  sb_add(sb, TELEMETRY_MARK)
+  sb_add(sb, "\",\"properties\":{")
+  if props != null and props.n > 0 {
+    for i in 0 .. sb_len(props.sb) { sb_byte(sb, props.sb.b[i]) }
+    sb_byte(sb, 44)
+  }
+  sb_add(sb, "\"$session_id\":")
+  tj_str(sb, telemetry_st.telemetry__session)
+  if len(telemetry__conf(telemetry_st).lib) > 0 {
+    sb_add(sb, ",\"$lib\":")
+    tj_str(sb, telemetry__conf(telemetry_st).lib)
+  }
+  sb_add(sb, "},\"timestamp\":")
+  tj_stamp(sb, TelemetryWorld.clock_s())
+  sb_byte(sb, 125)
+  if tj_full(sb) or (props != null and tj_full(props.sb)) { return }
+  tr_add(telemetry_st, sb.b, sb_len(sb), mk)
 }
 
-# the queue on disk now, if it changed (a quit, a crash about to happen, a child starting)
+# the queue on disk now, if it changed (a quit, a crash about to happen, a child starting): the lines,
+# marks and all, a line each, written from the kept buffer
 export function telemetry_save(telemetry_st: mut TelemetryState) -> void {
-  if not telemetry_st.telemetry__dirty or telemetry_st.telemetry__q == null { return }
+  if not telemetry_st.telemetry__dirty or telemetry_st.telemetry__ring == null { return }
   telemetry_st.telemetry__dirty = false
   let f = telemetry__conf(telemetry_st).queue_file
   if len(f) == 0 { return }
-  if len(telemetry_st.telemetry__q) == 0 {
+  if telemetry_st.telemetry__n == 0 {
     if Fs.exists(f) { Fs.remove(f) }
     return
   }
-  Fs.write_text(f, Text.join(telemetry_st.telemetry__q, "\n") + "\n")
+  let out = telemetry_st.telemetry__out
+  sb_clear(out)
+  for i in 0 .. telemetry_st.telemetry__n {
+    tr_line_to(telemetry_st, i, out, null)
+    sb_byte(out, 10)
+  }
+  Fs.write_bytes(f, out.b, sb_len(out))
 }
 
 # the player turned it off: nothing more is sent, and nothing queued is kept, here or on disk
 export function telemetry_forget(telemetry_st: mut TelemetryState) -> void {
   telemetry__drop_request(telemetry_st)
-  telemetry_st.telemetry__q = new []string
+  if telemetry_st.telemetry__ring != null { tr_clear(telemetry_st) }
   telemetry_st.telemetry__dirty = false
   let f = telemetry__conf(telemetry_st).queue_file
   if len(f) > 0 and Fs.exists(f) { Fs.remove(f) }
 }
 
-function telemetry__queue_load(telemetry_st: mut TelemetryState) -> void {
-  telemetry_st.telemetry__q = new []string
-  let f = telemetry__conf(telemetry_st).queue_file
-  if len(f) == 0 { return }
-  let s = Fs.read_text(f)
-  if s == null { return }
-  let parts = Text.split(s, "\n")
-  for i in 0 .. len(parts) { if len(parts[i]) > 2 { push(telemetry_st.telemetry__q, parts[i]) } }
-  let max = telemetry__conf(telemetry_st).queue_max
-  if len(telemetry_st.telemetry__q) > max { telemetry__queue_drop(telemetry_st, len(telemetry_st.telemetry__q) - max) }
-}
-
-# drop the first n lines (sent, or the oldest past the cap)
-function telemetry__queue_drop(telemetry_st: mut TelemetryState, n: int) -> void {
-  let rest = new []string
-  for i in n .. len(telemetry_st.telemetry__q) { push(rest, telemetry_st.telemetry__q[i]) }
-  telemetry_st.telemetry__q = rest
-  telemetry_st.telemetry__dirty = true
-}
-
-# the batch: the first n lines joined, with the player id put in - no parsing
-export function telemetry_batch_body(telemetry_st: TelemetryState, n: int) -> string {
-  let part = new []string
-  for i in 0 .. n { push(part, telemetry_st.telemetry__q[i]) }
-  let head = Value.object()
-  Value.put(head, "api_key", Value.str(telemetry__conf(telemetry_st).key))
-  let h: string = Json.encode(head)
-  let body = h[0..len(h) - 1] + ",\"batch\":[" + Text.join(part, ",") + "]}"
-  return Text.replace(body, TELEMETRY_MARK, telemetry_st.telemetry__id)
-}
-
-function telemetry__read_obj(path: string) -> Val {
-  if len(path) == 0 { return null }
-  let s = Fs.read_text(path)
-  if s == null { return null }
-  let v = Json.parse(s)
-  if v == null { return null }
-  if Value.kind(v) != 6 {
-    Json.free(v)
-    return null
+# the batch: the first n lines joined with the player id put in, into the kept buffer (tb_batch), and
+# as text for a test
+function tb_batch(telemetry_st: TelemetryState, n: int) -> void {
+  let out = telemetry_st.telemetry__out
+  sb_clear(out)
+  sb_add(out, "{\"api_key\":")
+  tj_str(out, telemetry__conf(telemetry_st).key)
+  sb_add(out, ",\"batch\":[")
+  for i in 0 .. n {
+    if i > 0 { sb_byte(out, 44) }
+    tr_line_to(telemetry_st, i, out, telemetry_st.telemetry__id)
   }
-  return v
+  sb_add(out, "]}")
+}
+export function telemetry_batch_body(telemetry_st: TelemetryState, n: int) -> string {
+  tb_batch(telemetry_st, Math.min(n, telemetry_st.telemetry__n))
+  return text_of(telemetry_st.telemetry__out.b, sb_len(telemetry_st.telemetry__out))
 }
diff --git a/packages/ludic.telemetry/ring.ludic b/packages/ludic.telemetry/ring.ludic
new file mode 100644
index 00000000..809f3c07
--- /dev/null
+++ b/packages/ludic.telemetry/ring.ludic
@@ -0,0 +1,76 @@
+# ring.ludic - the queued lines in one byte ring made at the start: a line's bytes, its length and where
+# its player mark is, oldest first. Full (lines or bytes), the oldest are overwritten; nothing is made
+# per event, per drop or per send
+
+# the ring for this start, made once at its size and kept across starts of the same size
+function tr_init(telemetry_st: mut TelemetryState) -> void {
+  let c = telemetry__conf(telemetry_st)
+  if telemetry_st.telemetry__ring == null or len(telemetry_st.telemetry__ring) != c.ring_bytes {
+    telemetry_st.telemetry__ring = buffer(c.ring_bytes)
+    telemetry_st.telemetry__out = sb_new(c.ring_bytes + c.batch * 128 + 1024)
+  }
+  if telemetry_st.telemetry__off == null or len(telemetry_st.telemetry__off) != c.queue_max {
+    telemetry_st.telemetry__off = words(c.queue_max)
+    telemetry_st.telemetry__len = words(c.queue_max)
+    telemetry_st.telemetry__mk = words(c.queue_max)
+  }
+  tr_clear(telemetry_st)
+}
+function tr_clear(telemetry_st: mut TelemetryState) -> void {
+  telemetry_st.telemetry__head = 0
+  telemetry_st.telemetry__n = 0
+  telemetry_st.telemetry__wr = 0
+}
+function tr_slot(telemetry_st: TelemetryState, i: int) -> int { return (telemetry_st.telemetry__head + i) % len(telemetry_st.telemetry__off) }
+
+# the oldest k lines gone (sent, or overwritten)
+function tr_drop(telemetry_st: mut TelemetryState, k: int) -> void {
+  let n = Math.min(k, telemetry_st.telemetry__n)
+  telemetry_st.telemetry__head = tr_slot(telemetry_st, n)
+  telemetry_st.telemetry__n -= n
+  if telemetry_st.telemetry__n == 0 { tr_clear(telemetry_st) }
+  telemetry_st.telemetry__dirty = true
+}
+
+# a line (the first `n` bytes of b) put at the ring's end, its mark `mk` bytes in (-1 none)
+function tr_add(telemetry_st: mut TelemetryState, b: []byte, n: int, mk: int) -> void {
+  let ring = telemetry_st.telemetry__ring
+  if n <= 0 or n > len(ring) { return }
+  if telemetry_st.telemetry__n == len(telemetry_st.telemetry__off) { tr_drop(telemetry_st, 1) }
+  var at = telemetry_st.telemetry__wr
+  if at + n > len(ring) { at = 0 }
+  while telemetry_st.telemetry__n > 0 and tr_over(telemetry_st, at, n) { tr_drop(telemetry_st, 1) }
+  for i in 0 .. n { ring[at + i] = b[i] }
+  let s = tr_slot(telemetry_st, telemetry_st.telemetry__n)
+  telemetry_st.telemetry__off[s] = at
+  telemetry_st.telemetry__len[s] = n
+  telemetry_st.telemetry__mk[s] = mk
+  telemetry_st.telemetry__n += 1
+  telemetry_st.telemetry__wr = at + n
+  telemetry_st.telemetry__dirty = true
+}
+# would bytes at .. at + n overwrite the oldest line
+function tr_over(telemetry_st: TelemetryState, at: int, n: int) -> bool {
+  let s = telemetry_st.telemetry__head
+  let o = telemetry_st.telemetry__off[s]
+  return o < at + n and at < o + telemetry_st.telemetry__len[s]
+}
+
+# line i (0 the oldest) onto sb, its mark written as `id` when id is not null
+function tr_line_to(telemetry_st: TelemetryState, i: int, sb: StrBuf, id: string) -> void {
+  let s = tr_slot(telemetry_st, i)
+  let o = telemetry_st.telemetry__off[s]
+  let n = telemetry_st.telemetry__len[s]
+  let mk = telemetry_st.telemetry__mk[s]
+  let ring = telemetry_st.telemetry__ring
+  var k = 0
+  while k < n {
+    if id != null and k == mk {
+      sb_add(sb, id)
+      k += len(TELEMETRY_MARK)
+    } else {
+      sb_byte(sb, ring[o + k])
+      k += 1
+    }
+  }
+}
diff --git a/packages/ludic.telemetry/send.ludic b/packages/ludic.telemetry/send.ludic
index 654c574a..ab4dc84a 100644
--- a/packages/ludic.telemetry/send.ludic
+++ b/packages/ludic.telemetry/send.ludic
@@ -5,7 +5,7 @@ export function telemetry_tick(telemetry_st: mut TelemetryState) -> void {
   if not telemetry_st.telemetry__ready { return }
   telemetry__id_tick(telemetry_st)
   if not telemetry__enabled() {
-    if len(telemetry_st.telemetry__q) > 0 or telemetry_st.telemetry__h >= 0 { telemetry_forget(telemetry_st) }
+    if telemetry_st.telemetry__n > 0 or telemetry_st.telemetry__h >= 0 { telemetry_forget(telemetry_st) }
     return
   }
   if not telemetry__can_send(telemetry_st) { return }
@@ -24,8 +24,8 @@ export function telemetry_tick(telemetry_st: mut TelemetryState) -> void {
     telemetry__answer(telemetry_st, now)
     return
   }
-  if len(telemetry_st.telemetry__q) == 0 { return }
-  let early = telemetry_st.telemetry__fails == 0 and len(telemetry_st.telemetry__q) >= c.flush_at
+  if telemetry_st.telemetry__n == 0 { return }
+  let early = telemetry_st.telemetry__fails == 0 and telemetry_st.telemetry__n >= c.flush_at
   if early or now >= telemetry_st.telemetry__next_ms {
     telemetry_save(telemetry_st)
     telemetry__flush(telemetry_st, now)
@@ -38,7 +38,7 @@ function telemetry__answer(telemetry_st: mut TelemetryState, now: int) -> void {
   if st < 0 { return }
   telemetry_st.telemetry__h = -1
   if st > 0 {
-    telemetry__queue_drop(telemetry_st, telemetry_st.telemetry__sent_n)
+    tr_drop(telemetry_st, telemetry_st.telemetry__sent_n)
     telemetry_st.telemetry__fails = 0
     telemetry_st.telemetry__next_ms = now + telemetry__conf(telemetry_st).flush_ms
     telemetry__fact(telemetry_st, TELEMETRY_SENT, telemetry_st.telemetry__sent_n, st, 0)
@@ -50,9 +50,10 @@ function telemetry__answer(telemetry_st: mut TelemetryState, now: int) -> void {
 }
 
 function telemetry__flush(telemetry_st: mut TelemetryState, now: int) -> void {
-  if telemetry_st.telemetry__h >= 0 or len(telemetry_st.telemetry__id) == 0 or len(telemetry_st.telemetry__q) == 0 { return }
-  let n = min(telemetry__conf(telemetry_st).batch, len(telemetry_st.telemetry__q))
-  let h = telemetry__send(telemetry_st, telemetry_batch_body(telemetry_st, n))
+  if telemetry_st.telemetry__h >= 0 or len(telemetry_st.telemetry__id) == 0 or telemetry_st.telemetry__n == 0 { return }
+  let n = min(telemetry__conf(telemetry_st).batch, telemetry_st.telemetry__n)
+  tb_batch(telemetry_st, n)
+  let h = telemetry__send(telemetry_st, telemetry_st.telemetry__out.b, sb_len(telemetry_st.telemetry__out))
   if h < 0 {
     telemetry__backoff(telemetry_st, now)
     telemetry__fact(telemetry_st, TELEMETRY_FAILED, n, 0, telemetry_st.telemetry__next_ms - now)
diff --git a/packages/ludic.telemetry/stamp.ludic b/packages/ludic.telemetry/stamp.ludic
new file mode 100644
index 00000000..6702347b
--- /dev/null
+++ b/packages/ludic.telemetry/stamp.ludic
@@ -0,0 +1,35 @@
+# stamp.ludic - the ISO time an event happened, written from the wall clock's seconds with the date
+# worked out in whole numbers (days from the civil calendar), not a string built by DateTime
+function tj_stamp(sb: StrBuf, secs: int) -> void {
+  var days = secs / 86400
+  var rem = secs % 86400
+  if rem < 0 {
+    rem += 86400
+    days -= 1
+  }
+  let z = days + 719468
+  var era = z / 146097
+  if z < 0 { era = (z - 146096) / 146097 }
+  let doe = z - era * 146097
+  let yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365
+  let doy = doe - (365 * yoe + yoe / 4 - yoe / 100)
+  let mp = (5 * doy + 2) / 153
+  let d = doy - (153 * mp + 2) / 5 + 1
+  var m = mp + 3
+  if mp >= 10 { m = mp - 9 }
+  var y = yoe + era * 400
+  if m <= 2 { y += 1 }
+  sb_byte(sb, 34)
+  sb_int(sb, y)
+  sb_byte(sb, 45)
+  sb_int2(sb, m)
+  sb_byte(sb, 45)
+  sb_int2(sb, d)
+  sb_byte(sb, 84)
+  sb_int2(sb, rem / 3600)
+  sb_byte(sb, 58)
+  sb_int2(sb, (rem / 60) % 60)
+  sb_byte(sb, 58)
+  sb_int2(sb, rem % 60)
+  sb_add(sb, "Z\"")
+}
diff --git a/packages/ludic.telemetry/state.ludic b/packages/ludic.telemetry/state.ludic
index d8280f28..2c3ee351 100644
--- a/packages/ludic.telemetry/state.ludic
+++ b/packages/ludic.telemetry/state.ludic
@@ -12,7 +12,8 @@ export property TelemetryConfig {
   flush_ms: int = 30000        # a batch this often
   flush_at: int = 50           # or sooner, at this many events
   batch: int = 200             # events in one request
-  queue_max: int = 5000        # the oldest go past this
+  queue_max: int = 5000        # the oldest go past this, or past ring_bytes of lines
+  ring_bytes: int = 1048576    # the lines' ring (ring.ludic), made once at the start
   backoff_max: int = 6         # the wait doubles at most this many times
   save_ms: int = 5000          # the queue on disk at most this far behind
 }
@@ -22,13 +23,13 @@ export port TelemetryWorld {
   can_send: fn() -> bool = fn telemetry__yes     # may this run send at all (a test, a dev build: no)
   enabled: fn() -> bool = fn telemetry__yes      # the player's switch; off forgets everything queued
   now_ms: fn() -> int = fn telemetry__wall_ms    # a clock in milliseconds
-  stamp: fn() -> string = fn telemetry__wall_stamp  # the ISO time an event happened
+  clock_s: fn() -> int = fn telemetry__wall_s   # the wall clock in seconds since 1970, for an event's time
 }
 
 # how a batch travels (unbound: Http). send returns a handle (< 0: could not start); poll
 # answers -1 while pending, 0 on failure, 1 when the server took it; drop abandons one.
 export port TelemetryTransport {
-  send: fn(string, string) -> int = fn telemetry__http_send
+  send: fn(string, []byte, int) -> int = fn telemetry__http_send   # (url, body, its length)
   poll: fn(int) -> int = fn telemetry__http_poll
   drop: fn(int) -> void = fn telemetry__http_drop
 }
@@ -56,8 +57,21 @@ export state TelemetryState {
   telemetry__ready: bool = false
   telemetry__id: string = ""
   telemetry__session: string = ""
-  telemetry__q: []string = null         # the queued lines, oldest first
-  telemetry__dirty: bool = false        # telemetry__q differs from the file
+  telemetry__ring: []byte = null        # the queued lines (ring.ludic), oldest first from head
+  telemetry__off: []int = null
+  telemetry__len: []int = null
+  telemetry__mk: []int = null           # where each line's player mark is, -1 none
+  telemetry__head: int = 0
+  telemetry__n: int = 0
+  telemetry__wr: int = 0
+  telemetry__line: StrBuf = sb_new(TELEMETRY_LINE)   # an event's line, written here
+  telemetry__props: TelemetryProps = telemetry__props_new()
+  telemetry__out: StrBuf = null         # a batch or the file, written here
+  telemetry__url: string = ""           # host and path, joined once at the config
+  telemetry__fpool: []TelemetryFact = new []TelemetryFact   # fact records, reused once no drain holds one
+  telemetry__ffree: []TelemetryFact = new []TelemetryFact
+  telemetry__fnext: []int = words(1)
+  telemetry__dirty: bool = false        # the ring differs from the file
   telemetry__h: int = -1                # the batch in flight
   telemetry__sent_n: int = 0            # how many lines it carries
   telemetry__next_ms: int = 0           # when the next send may go
@@ -71,8 +85,8 @@ export function telemetry_facts(telemetry_st: TelemetryState) -> Queue<Telemetry
   return telemetry_st.telemetry__facts
 }
 
-function telemetry__fact(telemetry_st: TelemetryState, what: int, count: int, status: int, retry: int) -> void {
-  let f = new TelemetryFact
+function telemetry__fact(telemetry_st: mut TelemetryState, what: int, count: int, status: int, retry: int) -> void {
+  let f = telemetry__fact_record(telemetry_st)
   f.what = what
   f.count = count
   f.status = status
@@ -80,3 +94,9 @@ function telemetry__fact(telemetry_st: TelemetryState, what: int, count: int, st
   q_push(telemetry_facts(telemetry_st), f)
 }
 function telemetry__facts__new() -> Queue<TelemetryFact> { return queue_new("telemetry.facts") }
+function telemetry__props_new() -> TelemetryProps {
+  let p = new TelemetryProps
+  p.sb = sb_new(TELEMETRY_LINE)
+  p.lv = words(8)
+  return p
+}
diff --git a/packages/ludic.telemetry/tests/ring_test.ludic b/packages/ludic.telemetry/tests/ring_test.ludic
new file mode 100644
index 00000000..ed079c1a
--- /dev/null
+++ b/packages/ludic.telemetry/tests/ring_test.ludic
@@ -0,0 +1,125 @@
+# ring_test.ludic - an event written once into a kept line and the queue a ring of bytes: ten thousand
+# events, most past the cap in lines and in bytes, make nothing; the line is exact JSON with its time
+# worked out from the seconds; the batch puts the id in; the file round-trips with its marks
+import "ludic.telemetry"
+import "ludic.base"
+program RingTest {
+  numbers float
+  state RingTestState {
+    now: int = 1790337600
+    body: string = ""
+  }
+  function fk_now() -> int { return 0 }
+  function fk_on() -> bool { return true }
+  function fk_clock(ring_test_st: RingTestState) -> int { return ring_test_st.now }
+  function fk_send(url: string, body: []byte, n: int) -> int { return -1 }
+  function fk_poll(h: int) -> int { return -1 }
+  function fk_drop(h: int) -> void { }
+  bind TelemetryWorld { can_send: fn fk_on, enabled: fn fk_on, now_ms: fn fk_now, clock_s: fn fk_clock }
+  bind TelemetryTransport { send: fn fk_send, poll: fn fk_poll, drop: fn fk_drop }
+
+  function qfile() -> string { return Os.temp_dir() + "/ludic-telemetry-ring-queue.txt" }
+  function start(telemetry_st: mut TelemetryState, max: int, bytes: int) -> void {
+    telemetry_reset(telemetry_st)
+    if Fs.exists(qfile()) { Fs.remove(qfile()) }
+    Fs.write_text(Os.temp_dir() + "/ludic-telemetry-ring-id.json", "{\"id\":\"p-9\"}")
+    let c = new TelemetryConfig
+    c.host = "http://fake"
+    c.key = "k-9"
+    c.lib = "ring"
+    c.queue_file = qfile()
+    c.id_file = Os.temp_dir() + "/ludic-telemetry-ring-id.json"
+    c.queue_max = max
+    c.ring_bytes = bytes
+    c.batch = 3
+    telemetry_config(telemetry_st, c)
+    telemetry_start(telemetry_st)
+  }
+  function one(telemetry_st: mut TelemetryState, k: int) -> void {
+    let p = telemetry_props(telemetry_st)
+    telemetry_int(p, "n", k)
+    telemetry_str(p, "what", "a fish")
+    telemetry_bool(p, "dev", true)
+    telemetry_event(telemetry_st, "caught", p)
+  }
+
+  test "ten thousand events, past the cap in lines and in bytes, make nothing" (telemetry_st: mut TelemetryState) {
+    start(telemetry_st, 5000, 262144)
+    for k in 0 .. 200 { one(telemetry_st, k) }
+    let heap = Os.heap_bytes()
+    for k in 0 .. 10000 { one(telemetry_st, k) }
+    let grew = Os.heap_bytes() - heap
+    print(`ring: 10000 events, {telemetry_queued(telemetry_st)} held, heap {grew} bytes`)
+    expect(grew == long(0))
+    expect(Text.contains(telemetry_line(telemetry_st, telemetry_queued(telemetry_st) - 1), "\"n\":9999"))
+    start(telemetry_st, 40, 1048576)
+    let heap2 = Os.heap_bytes()
+    for k in 0 .. 10000 { one(telemetry_st, k) }
+    expect(Os.heap_bytes() - heap2 == long(0))
+    expect_eq(telemetry_queued(telemetry_st), 40)
+    expect(Text.contains(telemetry_line(telemetry_st, 0), "\"n\":9960"))
+  }
+
+  test "a line is exact JSON, escaped, its time from the seconds" (telemetry_st: mut TelemetryState, ring_test_st: mut RingTestState) {
+    start(telemetry_st, 50, 65536)
+    let p = telemetry_props(telemetry_st)
+    telemetry_str(p, "say", "a \"quote\"\\ and\na line")
+    telemetry_event(telemetry_st, "said", p)
+    ring_test_st.now = 951868799
+    telemetry_event(telemetry_st, "leap", null)
+    let a = telemetry_line(telemetry_st, 0)
+    expect(Text.contains(a, "\"properties\":{\"say\":\"a \\\"quote\\\"\\\\ and\\u000aa line\",\"$session_id\":"))
+    expect(Text.contains(a, "\"timestamp\":\"2026-09-25T12:00:00Z\"}"))
+    expect(Json.parse(a) != null)
+    expect(Text.contains(telemetry_line(telemetry_st, 1), "\"timestamp\":\"2000-02-29T23:59:59Z\""))
+    expect(Text.contains(telemetry_line(telemetry_st, 1), "\"properties\":{\"$session_id\""))
+  }
+
+  test "the batch puts the id in, and the file round-trips with its marks" (telemetry_st: mut TelemetryState) {
+    start(telemetry_st, 50, 65536)
+    for k in 0 .. 4 { one(telemetry_st, k) }
+    let body = telemetry_batch_body(telemetry_st, 3)
+    expect(Text.starts_with(body, "{\"api_key\":\"k-9\",\"batch\":[{"))
+    expect(Text.contains(body, "\"distinct_id\":\"p-9\""))
+    expect(not Text.contains(body, "\"n\":3"))
+    expect(Json.parse(body) != null)
+    telemetry_save(telemetry_st)
+    telemetry_reset(telemetry_st)
+    telemetry_start(telemetry_st)
+    expect_eq(telemetry_queued(telemetry_st), 4)
+    expect(Text.contains(telemetry_batch_body(telemetry_st, 4), "\"n\":3,"))
+    expect(not Text.contains(telemetry_batch_body(telemetry_st, 4), "TELEMETRY_PLAYER"))
+  }
+
+  test "an object and a list inside the properties are JSON, and the signature tells a change" (telemetry_st: mut TelemetryState) {
+    start(telemetry_st, 50, 65536)
+    let p = telemetry_props(telemetry_st)
+    telemetry_int(p, "grade", 3)
+    telemetry_list(p, "subjects")
+    telemetry_item_str(p, "elk")
+    telemetry_item_str(p, "deer")
+    telemetry_list_end(p)
+    telemetry_obj(p, "$set")
+    telemetry_str(p, "arch", "arm64")
+    telemetry_list(p, "looks")
+    let sb = telemetry_item_open(p)
+    sb_int(sb, 4)
+    sb_byte(sb, 44)
+    sb_int(sb, 2)
+    telemetry_item_close(p)
+    telemetry_list_end(p)
+    telemetry_obj_end(p)
+    let lk = telemetry_str_open(p, "look")
+    sb_int(lk, 7)
+    telemetry_item_close(p)
+    telemetry_bool(p, "last", false)
+    let sig = telemetry_props_sig(p)
+    telemetry_event(telemetry_st, "shot", p)
+    let a = telemetry_line(telemetry_st, 0)
+    expect(Text.contains(a, "{\"grade\":3,\"subjects\":[\"elk\",\"deer\"],\"$set\":{\"arch\":\"arm64\",\"looks\":[\"4,2\"]},\"look\":\"7\",\"last\":false,"))
+    expect(Json.parse(a) != null)
+    let q = telemetry_props(telemetry_st)
+    telemetry_int(q, "grade", 3)
+    expect(telemetry_props_sig(q) != sig)
+  }
+}
diff --git a/packages/ludic.telemetry/tests/telemetry_test.ludic b/packages/ludic.telemetry/tests/telemetry_test.ludic
index 3c6edaa0..03879152 100644
--- a/packages/ludic.telemetry/tests/telemetry_test.ludic
+++ b/packages/ludic.telemetry/tests/telemetry_test.ludic
@@ -18,18 +18,18 @@ program TelemetryTest {
   function fake_now(telemetry_test_st: TelemetryTestState) -> int { return telemetry_test_st.clock }
   function fake_enabled(telemetry_test_st: TelemetryTestState) -> bool { return telemetry_test_st.on }
   function fake_can(telemetry_test_st: TelemetryTestState) -> bool { return telemetry_test_st.allowed }
-  function fake_stamp() -> string { return "2026-09-25T12:00:00Z" }
-  function fake_send(telemetry_test_st: mut TelemetryTestState, url: string, body: string) -> int {
+  function fake_clock() -> int { return 1790337600 }
+  function fake_send(telemetry_test_st: mut TelemetryTestState, url: string, body: []byte, n: int) -> int {
     if telemetry_test_st.refuse { return -1 }
     telemetry_test_st.sends += 1
     telemetry_test_st.last_url = url
-    telemetry_test_st.last_body = body
+    telemetry_test_st.last_body = text_of(body, n)
     return 7
   }
   function fake_poll(telemetry_test_st: TelemetryTestState, h: int) -> int { return telemetry_test_st.answer }
   function fake_drop(h: int) -> void { }
 
-  bind TelemetryWorld { can_send: fn fake_can, enabled: fn fake_enabled, now_ms: fn fake_now, stamp: fn fake_stamp }
+  bind TelemetryWorld { can_send: fn fake_can, enabled: fn fake_enabled, now_ms: fn fake_now, clock_s: fn fake_clock }
   bind TelemetryTransport { send: fn fake_send, poll: fn fake_poll, drop: fn fake_drop }
 
   function qfile() -> string { return Os.temp_dir() + "/ludic-telemetry-test-queue.txt" }