Keep a dead server explainable after its record is pruned

[subwire]

Stacked on #223 — branched from server-startup-reliability, so review the top commit only. Retarget to main once #223 lands.

The gap

#223 made a dead server say so, instead of reading as "you never started one". It works — for exactly one command.

That command prunes the registry entry. Every command after it goes blind again. And the command that usually gets there first is list, the single most-used verb, which prints a bare:

No running decompiler servers.  (registry: /home/ctf/.local/state/declib/servers)

…which reads precisely like nothing was ever started. The diagnosis is destroyed by the command used to check state.

Measured

On a 40-binary benchmark run, of 79 "missing server" errors:

	count
carried the useful diagnosis	10
corpse already eaten by an intervening list	69

Reproduced deterministically

# no `list` in between — works
load → kill -9 → list_functions --id X
  "server X is no longer running (binary: /tmp/target). It died or was
   stopped; its analysis is gone.  Reload it with: decompiler load ..."

# `list` in between — which is what agents actually do
load → kill -9 → list → list_functions --id X
  "No running decompiler server matches {'id': 'X'}."

Change

Pruning leaves a tombstone beside the registry entry, so the death stays explainable for any later command.

• list now reports recent deaths with the reload command, instead of implying nothing ever ran
• a successful load of the same binary clears the tombstone, so a stale death is never reported as current
• tombstones are a hint, not a log: capped at the 16 most recent, and excluded from the live-record glob so one can never be mistaken for a running server

After:

No running decompiler servers.  (registry: ...)

Recently died (analysis is gone; reload to continue):
  095d5185f3   /tmp/target
      reload: decompiler load /tmp/target --backend ida

Tests

Five: pruning leaves a tombstone; the diagnosis survives a second lookup (the actual regression); tombstones are never mistaken for live records; reload clears them; the count is capped.

🤖 Generated with Claude Code