feat(session): refuse session logs a build cannot faithfully read

Old runtimes meeting a newer session format now fail loud instead of
misreading: version refusal names the direction (newer: upgrade the
harness; older: no upgrade path) and points at the raw JSONL log, and an
event type outside the generated known vocabulary refuses resume unless
its envelope carries the new ignorable: true marker (default: required,
so a forgotten marker over-refuses instead of silently resuming a gutted
session). gen-persistence-catalog now also emits
KNOWN_SESSION_EVENT_TYPES; SQLite stores the marker in a dedicated
column (SCHEMA_VERSION 15). The versioning design (monotonic integer,
n->n+1 upgrader chain, migrate-on-continue) is recorded in the
session-log-version-mechanism Agent Note.

packages/session/session-persistence-jsonl/tests/jsonl.spec.ts

@@ -186,6 +186,23 @@ describe('SessionPersistenceJsonl: format helpers', () => {
     })
     await fiber.dispose()
   })
+
+  it('points a format refusal at the raw log path', async () => {
+    const absoluteRoot = await freshRoot()
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    const fiber = await ctx.plugin(SessionPersistenceJsonl, { root: absoluteRoot, compression: 'none' })
+    const m = { ...meta('newer-format', '/work'), version: 7 }
+    await ctx.sessionPersistence.create(m)
+    await ctx.sessionPersistence.append(m.id, [
+      { type: 'turn/start', seq: 0, time: 1, data: { turn: 1 } },
+      { type: 'turn/end', seq: 1, time: 2, data: { turn: 1, reason: { kind: 'completed' } } },
+    ])
+    const failure = await ctx.sessionPersistence.load(m.id).then(() => undefined, (error: unknown) => error as Error)
+    expect(failure?.name).toBe('SessionFormatUnsupportedError')
+    expect(failure?.message).toContain(`(raw log: ${rawLogPath(resolve(absoluteRoot), '/work', m.id)})`)
+    await fiber.dispose()
+  })
 })
 
 describe('SessionPersistenceJsonl: durability and crash semantics', () => {