feat(piggy): piggy list/add/remove (v0.6.0)HEADv0.6.0master

New `piggy` group:
- `piggy list` lists piggy banks with saved/target amounts and linked
  accounts.
- `piggy add|remove <name|id> <amount> [--account NAME]` changes the
  saved amount on a linked account via PUT /piggy-banks/{id}.

Firefly syncs the whole account list on that PUT, so every linked account
is resent (others without current_amount, which keeps their value) or it
would be unlinked. Removing below zero is rejected before any write, and
the saved amount is read back so a refused add fails loudly instead of
returning 200 unchanged.

add/remove currently hit an upstream bug on Firefly III <= 6.7.9:
PiggyBankFactory::linkToAccountIds passes the pivot current_amount (an int
from the DB) to bcsub() uncast, so any PUT with "accounts" 500s
(firefly-iii/firefly-iii#13063). Documented in SKILL.md/README; the live
integration test skips on that error and runs once upstream is fixed.

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

2 files changed, 82 insertions, 1 deletions

diff --git a/firefly_cli/commands/__init__.py b/firefly_cli/commands/__init__.py
index e87c623..99762a6 100644
--- a/firefly_cli/commands/__init__.py
+++ b/firefly_cli/commands/__init__.py
@@ -1,3 +1,3 @@
 # Copyright (C) 2026 Danilo M. <danix@danix.xyz>  GPL-2.0-only
 # Importing each module runs its @registry.command decorators.
-from firefly_cli.commands import auth, account, category, tag, transaction, budget  # noqa: F401
+from firefly_cli.commands import auth, account, category, tag, transaction, budget, piggy  # noqa: F401
diff --git a/firefly_cli/commands/piggy.py b/firefly_cli/commands/piggy.py
new file mode 100644
index 0000000..9ade3c8
--- /dev/null
+++ b/firefly_cli/commands/piggy.py
@@ -0,0 +1,81 @@
+# Copyright (C) 2026 Danilo M. <danix@danix.xyz>  GPL-2.0-only
+from decimal import Decimal, InvalidOperation
+from firefly_cli import registry, output
+from firefly_cli.errors import FireflyError
+
+
+@registry.command("piggy list", help="list piggy banks with saved/target amounts and linked accounts")
+def cmd_list(args, ctx):
+    resp = ctx.client.request("GET", "/api/v1/piggy-banks", params={"limit": 1000})
+    output.emit(output.unwrap(resp), human=ctx.human)
+    return 0
+
+
+def _move_args(p):
+    p.add_argument("ref", help="piggy bank name or id")
+    p.add_argument("amount", help="amount to move (positive)")
+    p.add_argument("--account", default=None,
+                   help="linked asset account name (required if the piggy bank has several)")
+
+
+def _amount(raw):
+    try:
+        amt = Decimal(str(raw))
+    except InvalidOperation:
+        amt = None
+    if amt is None or not amt.is_finite() or amt <= 0:
+        raise FireflyError(f'amount must be a positive number, got "{raw}"')
+    return amt
+
+
+def _move(args, ctx, sign):
+    amt = _amount(args.amount)
+    pb = ctx.resolver.piggy(args.ref)
+    linked = pb.get("accounts") or []
+    if args.account is None:
+        if len(linked) != 1:
+            raise FireflyError(
+                f'piggy bank "{pb.get("name")}" is linked to {len(linked)} accounts; '
+                "pass --account: " + ", ".join(a.get("name", "") for a in linked))
+        target = linked[0]
+    else:
+        hits = [a for a in linked if str(a.get("name", "")).lower() == args.account.lower()]
+        if len(hits) != 1:
+            raise FireflyError(
+                f'account "{args.account}" is not linked to piggy bank "{pb.get("name")}". '
+                "Linked: " + (", ".join(a.get("name", "") for a in linked) or "(none)"))
+        target = hits[0]
+
+    new = Decimal(str(target.get("current_amount") or "0")) + sign * amt
+    if new < 0:
+        raise FireflyError(
+            f'cannot remove {amt}: only {target.get("current_amount")} saved from {target.get("name")}')
+    new_s = f"{new:.2f}"
+    # Firefly syncs the whole account list on PUT, so every linked account must
+    # be resent or it gets unlinked. Omitting current_amount keeps its saved value.
+    body = {"accounts": [
+        {"account_id": a["account_id"], "current_amount": new_s} if a is target
+        else {"account_id": a["account_id"]}
+        for a in linked]}
+    resp = ctx.client.request("PUT", f"/api/v1/piggy-banks/{pb['id']}", body=body)
+    saved = output.unwrap(resp)
+    # Validation normally 422s an unaffordable add, but PiggyBankFactory can
+    # still skip it and answer 200. Read back and fail loudly instead.
+    after = next((a for a in saved.get("accounts") or []
+                  if str(a.get("account_id")) == str(target["account_id"])), {})
+    if Decimal(str(after.get("current_amount") or "0")) != new:
+        raise FireflyError(
+            f'Firefly did not apply the change (saved {after.get("current_amount")}, wanted {new_s}): '
+            "not enough unallocated money on the account, or the target would be exceeded")
+    output.emit(saved, human=ctx.human)
+    return 0
+
+
+@registry.command("piggy add", help="put money into a piggy bank", args=_move_args)
+def cmd_add(args, ctx):
+    return _move(args, ctx, 1)
+
+
+@registry.command("piggy remove", help="take money out of a piggy bank", args=_move_args)
+def cmd_remove(args, ctx):
+    return _move(args, ctx, -1)