Context hygiene at insert time: result ids, read stubs, the cap, recall

Harness spec 3.0.0 (context.md, loop.json `context`), in session/results.ts,
applied by the engine when a result goes into the conversation and never
afterwards:

- every result is headed by its id ([#0001]); a read also by the path as
  given, its lines, the file's length and the first 8 hex digits of the
  content's SHA-256; an empty file says so;
- a read of an unchanged file whose lines lie inside an earlier full read is
  a stub naming it; a list/glob/grep repeated with the same arguments and the
  same result is "Same result as #…";
- output over 400 lines or 40,000 characters keeps head and tail with the
  elided line; the full result is kept with the session (a new `results`
  table in sessions.db, gone with the session);
- edit, multiedit, write and apply_patch answer with their hunks under a
  bracket with the new content's hash; a new file is "Created, N lines.";
- recall (new built-in tool) shows any stored result, or a range of it, also
  after a resume; ids are never reused;
- compaction appends the table of the reads still in the conversation to the
  summary.

A stub only ever points at a result still in the conversation, so after a
compaction, an /undo or a rewind the file is read in full. compaction.prune
is gone: cutting old outputs in place threw the prompt cache away (an old
config's key is dropped with a warning). blocks/context.md is in the prompt
wherever recall is offered. Conformance runner for the `context` area (11
cases pass).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/config/load.ts

@@ -121,6 +121,14 @@ function legacyKeys(all: Record<string, unknown>, file: string, notes: string[])
     if (!(typeof p === "string" && ["none", "default", "neutral"].includes(p.toLowerCase())))
       notes.push(`${file}: personality "${String(p)}" is not a preset any more (${PERSONALITIES.join(", ")}); none is used`)
   }
+  // compaction.prune cut old tool outputs in place, which threw the prompt cache away; harness spec
+  // 3.0.0 never rewrites what was sent (context.md), so the key is gone.
+  const comp = all.compaction
+  if (comp && typeof comp === "object" && !Array.isArray(comp) && "prune" in comp) {
+    const { prune: _, ...rest } = comp as Record<string, unknown>
+    all.compaction = rest
+    notes.push(`${file}: compaction.prune was removed — old tool outputs are no longer cut afterwards; delete it`)
+  }
   // One file written as a plain string, not a list: read as the list of that one, not dropped
   // without a word by the schema.
   if (typeof all.instruction_files === "string") {