feat(harness-state): map pi events to v3

docs/vrs/08-harness-context/spec.md

@@ -415,7 +415,7 @@ number (HC-R02); where st2 computes it, the row says so.
 | --- | --- | --- | --- | --- | --- |
 | claude | 2.1.250 | `statusLine` command stdin JSON | `context_window.total_input_tokens` = `input + cache_creation + cache_read` of the last response | `context_window.context_window_size` | `context_window.used_percentage` — Claude's own integer, clamped 0..100 |
 | codex | codex-cli 0.151.0 | app-server `thread/tokenUsage/updated` | `tokenUsage.last.totalTokens` | `tokenUsage.modelContextWindow` | st2 computes with the baseline rule below; equals `100 −` Codex's displayed "% context left" |
-| pi | 0.84.2 | injected extension `ctx.getContextUsage()` | `.tokens` = last assistant `totalTokens` (input + output + cacheRead + cacheWrite) | `.contextWindow` | `.percent` (float) |
+| pi | 0.84.4 | injected extension `ctx.getContextUsage()` | `.tokens` = last assistant `totalTokens` (input + output + cacheRead + cacheWrite) | `.contextWindow` | `.percent` (float) |
 | omp | 18.0.9 (and 18.0.3) | injected extension `ctx.getContextUsage()` | `.tokens` = last assistant **`input`** only | `.contextWindow` | `.percent` (float) |
 | opencode | 1.18.25 | SSE `message.updated` joined with `GET /config/providers` | last **non-summary** assistant `tokens.total` | `providers[].models[<modelID>].limit.context` | st2 computes `usedTokens / windowTokens`; the server displays none |
 
@@ -727,7 +727,7 @@ turn the measurement into a semantic-version promise. Every later Codex release
 still requires its own source comparison and live delivery proof before the exact
 launch gate moves.
 
-### pi (0.84.2)
+### pi (0.84.4)
 
 One call answers everything, present on the `ctx` of every lifecycle event:
 `getContextUsage()` returns `{ tokens, contextWindow, percent }`.
@@ -1126,7 +1126,7 @@ each only once a real test proves it (per `CLAUDE.md`):
   baseline-free `last.totalTokens / window` reads 36, the truth is 33).
 
   **Shipped for pi and omp**:
-  `src/pi_channel.rs::the_pi_0_84_2_fixture_pins_total_tokens_as_the_numerator`,
+  `src/pi_channel.rs::the_pinned_pi_fixture_pins_total_tokens_as_the_numerator`,
   `src/pi_channel.rs::the_omp_18_0_9_fixture_pins_prompt_input_as_the_numerator`,
   `src/pi_channel.rs::a_pi_compaction_withholds_the_reading_it_emptied_in_the_same_write`,
   `src/pi_channel.rs::an_omp_compaction_yields_unknown_because_the_event_names_no_reason`,

flake.nix

@@ -492,10 +492,10 @@
         # without integrity hashes, which `fetchNpmDeps` cannot express.
         checks.pi-extension-types =
           let
-            piVersion = "0.84.2";
+            piVersion = "0.84.4";
             piTarball = pkgs.fetchurl {
               url = "https://registry.npmjs.org/@earendil-works/pi-coding-agent/-/pi-coding-agent-${piVersion}.tgz";
-              hash = "sha256-lbiZzXsaDB8BdMe/M6tCdDXjVTp9H0dWZhqpx/Gmj/o=";
+              hash = "sha256-W852bRnDzroY8/uq2RxEnJ+dc5gfnjQA7O+TIAbwaWg=";
             };
             nodeTypesTarball = pkgs.fetchurl {
               url = "https://registry.npmjs.org/@types/node/-/node-26.2.0.tgz";

hooks/omp-channel.ts

@@ -137,7 +137,7 @@ const terminalProviderError = (event: AgentEndFrame): ProviderError | undefined
  * build whose telemetry surface moved still loads and still delivers mail, and a widened cast alone
  * would make that tolerance absolute and silent. Erased at runtime.
  *
- * Note what this can and cannot prove for omp. It pins the SHAPE against pi 0.84.2's typings, which
+ * Note what this can and cannot prove for omp. It pins the SHAPE against pi 0.84.4's typings, which
  * is all this asset compiles against — omp ships no typings of its own. It cannot prove omp's
  * `tokens` still means prompt-only input, because that is a meaning and not a shape; the
  * version-pinned fixture in `src/pi_channel.rs` is what bounds that (HC-R13, HC-T03).

src/pi_session.rs

@@ -32,7 +32,13 @@ const EXTENSION: &str = "pi-channel.ts";
 /// type-checks and runtime-smokes the shipped asset against exactly this tarball. That makes the
 /// flake pin the gate for this constant, and `pi_channel`'s fixture asserts the two agree: a pi
 /// bump that changes what `getContextUsage().tokens` means must move both together or fail.
-pub const MEASURED_CONTEXT_VERSION: &str = "0.84.2";
+///
+/// Moved 0.84.2 -> 0.84.4 with the flake pin, and the arithmetic was re-verified rather than
+/// assumed: `getContextUsage()` (`dist/core/agent-session.js`) and `calculateContextTokens`
+/// (`dist/core/compaction/compaction.js:86-88`, `usage.totalTokens || input + output + cacheRead
+/// + cacheWrite`) are byte-identical between the two published tarballs, so the recorded fixture
+/// still means what it says under the newer pin.
+pub const MEASURED_CONTEXT_VERSION: &str = "0.84.4";
 
 /// The exact st2 executable the pi extension must spawn for its channel.
 pub const CHANNEL_BIN: &str = "ST2_PI_CHANNEL_BIN";