fix(kernel,server,workflow): per-stage retry budget, sane freestyle budget, tail /events

Three defects surfaced by a live headless freestyle_planning run (all made a
long execution workflow fail or stall in ways invisible to a REST operator):

1. retryCount was session-global (DefaultOrchestrationReducer): TransitionExecuted
   updated currentStageId but never reset retryCount, while shouldRetry gates on
   it per-stage. An early stage that burned its 3 retries starved every later
   stage of its own — the next stage's first *retryable* failure went terminal.
   Reset retryCount on stage entry; back-edge loops stay bounded by the separate
   refinementIterations counter. Regression test added.

2. Freestyle stages ran at StageConfig's 4096-token default (ExecutionPlanCompiler
   never set a budget) vs 16384-32768 for static role_pipeline stages. A tool-heavy
   stage truncated its context every round, evicting the file_read results it just
   gathered, so it re-read forever and never accumulated enough to write. Set 16384.

3. GET /events returned the OLDEST `limit` events (readFrom(0) then take): for a
   session past `limit` events the tail — including a pending ApprovalRequested —
   was invisible to a headless/REST poller, the exact caller POST /approve serves.
   Default now tails; explicit fromSeq still paginates forward.

infrastructure/workflow/src/main/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompiler.kt

@@ -15,6 +15,14 @@ import com.fasterxml.jackson.module.kotlin.readValue
 
 private const val TERMINAL = "done"
 
+// Freestyle plans don't specify a per-stage token budget, so without this every compiled stage
+// inherits StageConfig's 4096 default — 1/8th of what the static role_pipeline execution stages
+// use (16384–32768). At 4096 a tool-heavy stage (scaffold/implement) truncates its context every
+// round, evicting the file_read results the model just gathered, so it re-reads forever and never
+// accumulates enough to write. Match the static execution baseline. (gemma ctx is 32768, so this
+// leaves ample headroom for completion.)
+private const val DEFAULT_STAGE_TOKEN_BUDGET = 16384
+
 class ExecutionPlanCompiler(
     private val registry: ArtifactKindRegistry,
     // Names of every registered tool. A stage that references a tool the runtime can't resolve
@@ -55,6 +63,7 @@ class ExecutionPlanCompiler(
                 needs = s.needs.map { ArtifactId(it) }.toSet(),
                 allowedTools = s.tools.toSet(),
                 writeManifest = writeManifest,
+                tokenBudget = DEFAULT_STAGE_TOKEN_BUDGET,
                 metadata = mapOf("promptInline" to s.prompt),
             )
         }