Widen the accepted pimsync range to the 0.6 series; stream sync output and bound the Google HTTP calls

The version work and the sync-output work landed in one change; they can be
split apart if the history wants them separate.

flake.nix

@@ -3,8 +3,26 @@
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 
+  # pimsync is built from source rather than taken from nixpkgs, which trails
+  # the releases calcalist has been read against. Being an input rather than a
+  # `fetchFromSourcehut` call makes it substitutable: a fork or a working tree
+  # can be swapped in at install time with
+  # `--override-input pimsync-src git+file:///path/to/pimsync`, without the
+  # committed flake naming anything that exists on one machine only.
+  #
+  # The rev is the commit v0.6.0 points at: nix cannot peel an annotated tag,
+  # and resolving the ref alone fails.
+  inputs.pimsync-src = {
+    url = "git+https://git.sr.ht/~whynothugo/pimsync?ref=refs/tags/v0.6.0&rev=a111a44cd9e65c031ce9801fdced912057e4a4a0";
+    flake = false;
+  };
+
   outputs =
-    { self, nixpkgs }:
+    {
+      self,
+      nixpkgs,
+      pimsync-src,
+    }:
     let
       systems = [
         "x86_64-linux"
@@ -19,30 +37,48 @@
         let
           pkgs = import nixpkgs { inherit system; };
 
-          # nixpkgs currently ships pimsync 0.5.9, but `discover`'s output
-          # format is undocumented and changed between 0.5.9 and 0.5.11 —
-          # calcalist's parser only understands the newer shape (see
-          # SUPPORTED_PATCH_MIN in src/pimsync.rs). Build the exact version
-          # rather than trust whatever nixpkgs happens to carry.
-          pimsync0_5_11 = pkgs.rustPlatform.buildRustPackage (finalAttrs: {
-            pname = "pimsync";
-            version = "0.5.11";
-            src = pkgs.fetchFromSourcehut {
-              owner = "~whynothugo";
-              repo = "pimsync";
-              rev = "v${finalAttrs.version}";
-              hash = "sha256-iMdBqSSguViF+54e47IGV8hH3qvTxcNkWkmND1QAAxw=";
-            };
-            cargoHash = "sha256-dvkZ047eJnvYvyH1iW1NJo3Uv0L2T7waPYKN12bi+dA=";
+          # pimsync's Cargo.toml carries no version — the binary learns its own
+          # from `git describe`, which has nothing to describe inside the
+          # store. So it is assembled: the newest changelog heading for the
+          # release, and the input's revision for the tree it came from. That
+          # second half is what distinguishes an overridden fork from the
+          # upstream release it descends from, and a suffixed version is
+          # pimsync's own convention for a build off a tag.
+          pimsyncVersion =
+            let
+              lines = pkgs.lib.splitString "\n" (builtins.readFile "${pimsync-src}/CHANGELOG.rst");
+              isRelease = line: builtins.match "v[0-9]+\\.[0-9]+\\.[0-9]+" line != null;
+              newest =
+                pkgs.lib.findFirst isRelease (throw "no release heading found in pimsync's CHANGELOG.rst")
+                  lines;
+              release = pkgs.lib.removePrefix "v" newest;
+            in
+            "${release}-${pimsync-src.dirtyShortRev or pimsync-src.shortRev}";
 
-            # Skips build.rs's `git describe` call, which has nothing to
-            # describe once fetched as a plain source tarball.
-            env.PIMSYNC_VERSION = finalAttrs.version;
+          pimsync = pkgs.rustPlatform.buildRustPackage {
+            pname = "pimsync";
+            version = pimsyncVersion;
+            src = pimsync-src;
+
+            cargoLock = {
+              lockFile = "${pimsync-src}/Cargo.lock";
+
+              # pimsync pins a few dependencies to git revisions, and vstorage
+              # — which the fork swaps in — keeps libdav and libjmap as
+              # submodules of its own. Naming those revisions in
+              # `outputHashes` fetches them without submodules and vendors
+              # two empty directories; the builtin fetcher recurses properly.
+              # The revisions come from the lock file, so evaluation stays
+              # pure, and there is no hash here to go stale when a fork moves.
+              allowBuiltinFetchGit = true;
+            };
+
+            env.PIMSYNC_VERSION = pimsyncVersion;
 
             nativeBuildInputs = [ pkgs.pkg-config ];
             buildInputs = [ pkgs.sqlite ];
             doCheck = false;
-          });
+          };
         in
         rec {
           calcalist = pkgs.rustPlatform.buildRustPackage {
@@ -62,7 +98,7 @@
             # against, regardless of what else is on the user's PATH.
             postInstall = ''
               wrapProgram $out/bin/calcalist \
-                --prefix PATH : ${pkgs.lib.makeBinPath [ pimsync0_5_11 ]}
+                --prefix PATH : ${pkgs.lib.makeBinPath [ pimsync ]}
             '';
 
             meta = {