diff --git a/contrib/phabricator.py b/contrib/phabricator.py
new file mode 100644
--- /dev/null
+++ b/contrib/phabricator.py
@@ -0,0 +1,779 @@
+# phabricator.py - simple Phabricator integration
+#
+# Copyright 2017 Facebook, Inc.
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+"""simple Phabricator integration
+
+This extension provides a ``phabsend`` command which sends a stack of
+changesets to Phabricator without amending commit messages, and a ``phabread``
+command which prints a stack of revisions in a format suitable
+for :hg:`import`, and a ``phabupdate`` command to update statuses in batch.
+
+By default, Phabricator requires ``Test Plan`` which might prevent some
+changeset from being sent. The requirement could be disabled by changing
+``differential.require-test-plan-field`` config server side.
+
+Config::
+
+    [phabricator]
+    # Phabricator URL
+    url = https://phab.example.com/
+
+    # API token. Get it from https://$HOST/conduit/login/
+    token = cli-xxxxxxxxxxxxxxxxxxxxxxxxxxxx
+
+    # Repo callsign. If a repo has a URL https://$HOST/diffusion/FOO, then its
+    # callsign is "FOO".
+    callsign = FOO
+
+"""
+
+from __future__ import absolute_import
+
+import itertools
+import json
+import operator
+import re
+
+from mercurial.node import bin, nullid
+from mercurial.i18n import _
+from mercurial import (
+    cmdutil,
+    context,
+    encoding,
+    error,
+    mdiff,
+    obsolete,
+    parser,
+    patch,
+    registrar,
+    scmutil,
+    smartset,
+    tags,
+    url as urlmod,
+    util,
+)
+
+cmdtable = {}
+command = registrar.command(cmdtable)
+
+def urlencodenested(params):
+    """like urlencode, but works with nested parameters.
+
+    For example, if params is {'a': ['b', 'c'], 'd': {'e': 'f'}}, it will be
+    flattened to {'a[0]': 'b', 'a[1]': 'c', 'd[e]': 'f'} and then passed to
+    urlencode. Note: the encoding is consistent with PHP's http_build_query.
+    """
+    flatparams = util.sortdict()
+    def process(prefix, obj):
+        items = {list: enumerate, dict: lambda x: x.items()}.get(type(obj))
+        if items is None:
+            flatparams[prefix] = obj
+        else:
+            for k, v in items(obj):
+                if prefix:
+                    process('%s[%s]' % (prefix, k), v)
+                else:
+                    process(k, v)
+    process('', params)
+    return util.urlreq.urlencode(flatparams)
+
+def readurltoken(repo):
+    """return conduit url, token and make sure they exist
+
+    Currently read from [phabricator] config section. In the future, it might
+    make sense to read from .arcconfig and .arcrc as well.
+    """
+    values = []
+    section = 'phabricator'
+    for name in ['url', 'token']:
+        value = repo.ui.config(section, name)
+        if not value:
+            raise error.Abort(_('config %s.%s is required') % (section, name))
+        values.append(value)
+    return values
+
+def callconduit(repo, name, params):
+    """call Conduit API, params is a dict. return json.loads result, or None"""
+    host, token = readurltoken(repo)
+    url, authinfo = util.url('/'.join([host, 'api', name])).authinfo()
+    urlopener = urlmod.opener(repo.ui, authinfo)
+    repo.ui.debug('Conduit Call: %s %s\n' % (url, params))
+    params = params.copy()
+    params['api.token'] = token
+    request = util.urlreq.request(url, data=urlencodenested(params))
+    body = urlopener.open(request).read()
+    repo.ui.debug('Conduit Response: %s\n' % body)
+    parsed = json.loads(body)
+    if parsed.get(r'error_code'):
+        msg = (_('Conduit Error (%s): %s')
+               % (parsed[r'error_code'], parsed[r'error_info']))
+        raise error.Abort(msg)
+    return parsed[r'result']
+
+@command('debugcallconduit', [], _('METHOD'))
+def debugcallconduit(ui, repo, name):
+    """call Conduit API
+
+    Call parameters are read from stdin as a JSON blob. Result will be written
+    to stdout as a JSON blob.
+    """
+    params = json.loads(ui.fin.read())
+    result = callconduit(repo, name, params)
+    s = json.dumps(result, sort_keys=True, indent=2, separators=(',', ': '))
+    ui.write('%s\n' % s)
+
+def getrepophid(repo):
+    """given callsign, return repository PHID or None"""
+    # developer config: phabricator.repophid
+    repophid = repo.ui.config('phabricator', 'repophid')
+    if repophid:
+        return repophid
+    callsign = repo.ui.config('phabricator', 'callsign')
+    if not callsign:
+        return None
+    query = callconduit(repo, 'diffusion.repository.search',
+                        {'constraints': {'callsigns': [callsign]}})
+    if len(query[r'data']) == 0:
+        return None
+    repophid = encoding.strtolocal(query[r'data'][0][r'phid'])
+    repo.ui.setconfig('phabricator', 'repophid', repophid)
+    return repophid
+
+_differentialrevisiontagre = re.compile('\AD([1-9][0-9]*)\Z')
+_differentialrevisiondescre = re.compile(
+    '^Differential Revision:.*D([1-9][0-9]*)$', re.M)
+
+def getoldnodedrevmap(repo, nodelist):
+    """find previous nodes that has been sent to Phabricator
+
+    return {node: (oldnode or None, Differential Revision ID)}
+    for node in nodelist with known previous sent versions, or associated
+    Differential Revision IDs.
+
+    Examines commit messages like "Differential Revision:" to get the
+    association information.
+
+    If such commit message line is not found, examines all precursors and their
+    tags. Tags with format like "D1234" are considered a match and the node
+    with that tag, and the number after "D" (ex. 1234) will be returned.
+
+    The ``old node``, if not None, is guaranteed to be the last diff of
+    corresponding Differential Revision, and exist in the repo.
+    """
+    url, token = readurltoken(repo)
+    unfi = repo.unfiltered()
+    nodemap = unfi.changelog.nodemap
+
+    result = {} # {node: (oldnode or None, drev)}
+    toconfirm = {} # {node: (force, {precnode}, drev)}
+    for node in nodelist:
+        ctx = unfi[node]
+        # For tags like "D123", put them into "toconfirm" to verify later
+        precnodes = list(obsolete.allprecursors(unfi.obsstore, [node]))
+        for n in precnodes:
+            if n in nodemap:
+                for tag in unfi.nodetags(n):
+                    m = _differentialrevisiontagre.match(tag)
+                    if m:
+                        toconfirm[node] = (0, set(precnodes), int(m.group(1)))
+                        continue
+
+        # Check commit message. If "Differential Revision:" exists and matches
+        # the URL. Trust it blindly even if precursors do not match.
+        m = _differentialrevisiondescre.search(ctx.description())
+        if m:
+            toconfirm[node] = (1, set(precnodes), int(m.group(1)))
+
+    # Double check if tags are genuine by collecting all old nodes from
+    # Phabricator, and expect precursors overlap with it.
+    if toconfirm:
+        drevs = [drev for force, precs, drev in toconfirm.values()]
+        alldiffs = callconduit(unfi, 'differential.querydiffs',
+                               {'revisionIDs': drevs})
+        getnode = lambda d: bin(encoding.unitolocal(
+            getdiffmeta(d).get(r'node', ''))) or None
+        for newnode, (force, precset, drev) in toconfirm.items():
+            diffs = [d for d in alldiffs.values()
+                     if int(d[r'revisionID']) == drev]
+
+            # "precursors" as known by Phabricator
+            phprecset = set(getnode(d) for d in diffs)
+
+            # Ignore if precursors (Phabricator and local repo) do not overlap,
+            # and force is not set (when commit message says nothing)
+            if not force and not bool(phprecset & precset):
+                tagname = 'D%d' % drev
+                tags.tag(repo, tagname, nullid, message=None, user=None,
+                         date=None, local=True)
+                unfi.ui.warn(_('D%s: local tag removed - does not match '
+                               'Differential history\n') % drev)
+                continue
+
+            # Find the last node using Phabricator metadata, and make sure it
+            # exists in the repo
+            lastdiff = max(diffs, key=lambda d: int(d[r'id']))
+            oldnode = getnode(lastdiff)
+            if oldnode and oldnode not in nodemap:
+                oldnode = None
+
+            result[newnode] = (oldnode, drev)
+
+    return result
+
+def getdiff(ctx, diffopts):
+    """plain-text diff without header (user, commit message, etc)"""
+    output = util.stringio()
+    for chunk, _label in patch.diffui(ctx.repo(), ctx.p1().node(), ctx.node(),
+                                      None, opts=diffopts):
+        output.write(chunk)
+    return output.getvalue()
+
+def creatediff(ctx):
+    """create a Differential Diff"""
+    repo = ctx.repo()
+    repophid = getrepophid(repo)
+    # Create a "Differential Diff" via "differential.createrawdiff" API
+    params = {'diff': getdiff(ctx, mdiff.diffopts(git=True, context=32767))}
+    if repophid:
+        params['repositoryPHID'] = repophid
+    diff = callconduit(repo, 'differential.createrawdiff', params)
+    if not diff:
+        raise error.Abort(_('cannot create diff for %s') % ctx)
+    return diff
+
+def writediffproperties(ctx, diff):
+    """write metadata to diff so patches could be applied losslessly"""
+    params = {
+        'diff_id': diff[r'id'],
+        'name': 'hg:meta',
+        'data': json.dumps({
+            'user': ctx.user(),
+            'date': '%d %d' % ctx.date(),
+            'node': ctx.hex(),
+            'parent': ctx.p1().hex(),
+        }),
+    }
+    callconduit(ctx.repo(), 'differential.setdiffproperty', params)
+
+def createdifferentialrevision(ctx, revid=None, parentrevid=None, oldnode=None,
+                               actions=None):
+    """create or update a Differential Revision
+
+    If revid is None, create a new Differential Revision, otherwise update
+    revid. If parentrevid is not None, set it as a dependency.
+
+    If oldnode is not None, check if the patch content (without commit message
+    and metadata) has changed before creating another diff.
+
+    If actions is not None, they will be appended to the transaction.
+    """
+    repo = ctx.repo()
+    if oldnode:
+        diffopts = mdiff.diffopts(git=True, context=1)
+        oldctx = repo.unfiltered()[oldnode]
+        neednewdiff = (getdiff(ctx, diffopts) != getdiff(oldctx, diffopts))
+    else:
+        neednewdiff = True
+
+    transactions = []
+    if neednewdiff:
+        diff = creatediff(ctx)
+        writediffproperties(ctx, diff)
+        transactions.append({'type': 'update', 'value': diff[r'phid']})
+
+    # Use a temporary summary to set dependency. There might be better ways but
+    # I cannot find them for now. But do not do that if we are updating an
+    # existing revision (revid is not None) since that introduces visible
+    # churns (someone edited "Summary" twice) on the web page.
+    if parentrevid and revid is None:
+        summary = 'Depends on D%s' % parentrevid
+        transactions += [{'type': 'summary', 'value': summary},
+                         {'type': 'summary', 'value': ' '}]
+
+    if actions:
+        transactions += actions
+
+    # Parse commit message and update related fields.
+    desc = ctx.description()
+    info = callconduit(repo, 'differential.parsecommitmessage',
+                       {'corpus': desc})
+    for k, v in info[r'fields'].items():
+        if k in ['title', 'summary', 'testPlan']:
+            transactions.append({'type': k, 'value': v})
+
+    params = {'transactions': transactions}
+    if revid is not None:
+        # Update an existing Differential Revision
+        params['objectIdentifier'] = revid
+
+    revision = callconduit(repo, 'differential.revision.edit', params)
+    if not revision:
+        raise error.Abort(_('cannot create revision for %s') % ctx)
+
+    return revision
+
+def userphids(repo, names):
+    """convert user names to PHIDs"""
+    query = {'constraints': {'usernames': names}}
+    result = callconduit(repo, 'user.search', query)
+    # username not found is not an error of the API. So check if we have missed
+    # some names here.
+    data = result[r'data']
+    resolved = set(entry[r'fields'][r'username'] for entry in data)
+    unresolved = set(names) - resolved
+    if unresolved:
+        raise error.Abort(_('unknown username: %s')
+                          % ' '.join(sorted(unresolved)))
+    return [entry[r'phid'] for entry in data]
+
+@command('phabsend',
+         [('r', 'rev', [], _('revisions to send'), _('REV')),
+          ('', 'amend', False, _('update commit messages')),
+          ('', 'reviewer', [], _('specify reviewers'))],
+         _('REV [OPTIONS]'))
+def phabsend(ui, repo, *revs, **opts):
+    """upload changesets to Phabricator
+
+    If there are multiple revisions specified, they will be send as a stack
+    with a linear dependencies relationship using the order specified by the
+    revset.
+
+    If --amend is set, update commit messages so they have the
+    ``Differential Revision`` URL, remove related tags. This is similar to what
+    arcanist will do, and is more desired in author-push workflows. Otherwise,
+    use local tags to record the ``Differential Revision`` association.
+
+    phabsend will check obsstore and the above association to decide whether to
+    update an existing Differential Revision, or create a new one.
+    """
+    revs = list(revs) + opts.get('rev', [])
+    revs = scmutil.revrange(repo, revs)
+
+    if not revs:
+        raise error.Abort(_('phabsend requires at least one changeset'))
+    if opts.get('amend'):
+        cmdutil.checkunfinished(repo)
+
+    actions = []
+    reviewers = opts.get('reviewer', [])
+    if reviewers:
+        phids = userphids(repo, reviewers)
+        actions.append({'type': 'reviewers.add', 'value': phids})
+
+    oldnodedrev = getoldnodedrevmap(repo, [repo[r].node() for r in revs])
+
+    # Send patches one by one so we know their Differential Revision IDs and
+    # can provide dependency relationship
+    drevids = []
+    lastrevid = None
+    for rev in revs:
+        ui.debug('sending rev %d\n' % rev)
+        ctx = repo[rev]
+
+        # Get Differential Revision ID
+        oldnode, revid = oldnodedrev.get(ctx.node(), (None, None))
+        if oldnode != ctx.node():
+            # Create or update Differential Revision
+            revision = createdifferentialrevision(ctx, revid, lastrevid,
+                                                  oldnode, actions)
+            newrevid = int(revision[r'object'][r'id'])
+            if revid:
+                action = _('updated')
+            else:
+                action = _('created')
+
+            # Create a local tag to note the association, if commit message
+            # does not have it already
+            m = _differentialrevisiondescre.search(ctx.description())
+            if not m or int(m.group(1)) != newrevid:
+                tagname = 'D%d' % newrevid
+                tags.tag(repo, tagname, ctx.node(), message=None, user=None,
+                         date=None, local=True)
+        else:
+            # Nothing changed. But still set "newrevid" so the next revision
+            # could depend on this one.
+            newrevid = revid
+            action = _('skipped')
+
+        ui.write(_('D%s: %s - %s: %s\n') % (newrevid, action, ctx,
+                                            ctx.description().split('\n')[0]))
+        drevids.append(newrevid)
+        lastrevid = newrevid
+
+    # Update commit messages and remove tags
+    if opts.get('amend'):
+        unfi = repo.unfiltered()
+        drevs = callconduit(repo, 'differential.query', {'ids': drevids})
+        with repo.wlock(), repo.lock(), repo.transaction('phabsend'):
+            wnode = unfi['.'].node()
+            mapping = {} # {oldnode: newnode}
+            for i, rev in enumerate(revs):
+                old = unfi[rev]
+                drevid = drevids[i]
+                drev = [d for d in drevs if int(d[r'id']) == drevid][0]
+                newdesc = getdescfromdrev(drev)
+                # Make sure commit message contain "Differential Revision"
+                if old.description() != newdesc:
+                    parents = [
+                        mapping.get(old.p1().node(), (old.p1(),))[0],
+                        mapping.get(old.p2().node(), (old.p2(),))[0],
+                    ]
+                    new = context.metadataonlyctx(
+                        repo, old, parents=parents, text=newdesc,
+                        user=old.user(), date=old.date(), extra=old.extra())
+                    mapping[old.node()] = [new.commit()]
+                # Remove local tags since it's no longer necessary
+                tagname = 'D%d' % drevid
+                if tagname in repo.tags():
+                    tags.tag(repo, tagname, nullid, message=None, user=None,
+                             date=None, local=True)
+            scmutil.cleanupnodes(repo, mapping, 'phabsend')
+            if wnode in mapping:
+                unfi.setparents(mapping[wnode][0])
+
+# Map from "hg:meta" keys to header understood by "hg import". The order is
+# consistent with "hg export" output.
+_metanamemap = util.sortdict([(r'user', 'User'), (r'date', 'Date'),
+                              (r'node', 'Node ID'), (r'parent', 'Parent ')])
+
+_knownstatusnames = {'accepted', 'needsreview', 'needsrevision', 'closed',
+                     'abandoned'}
+
+def _getstatusname(drev):
+    """get normalized status name from a Differential Revision"""
+    return drev[r'statusName'].replace(' ', '').lower()
+
+# Small language to specify differential revisions. Support symbols: (), :X,
+# +, and -.
+
+_elements = {
+    # token-type: binding-strength, primary, prefix, infix, suffix
+    '(':      (12, None, ('group', 1, ')'), None, None),
+    ':':      (8, None, ('ancestors', 8), None, None),
+    '&':      (5,  None, None, ('and_', 5), None),
+    '+':      (4,  None, None, ('add', 4), None),
+    '-':      (4,  None, None, ('sub', 4), None),
+    ')':      (0,  None, None, None, None),
+    'symbol': (0, 'symbol', None, None, None),
+    'end':    (0, None, None, None, None),
+}
+
+def _tokenize(text):
+    view = memoryview(text) # zero-copy slice
+    special = '():+-& '
+    pos = 0
+    length = len(text)
+    while pos < length:
+        symbol = ''.join(itertools.takewhile(lambda ch: ch not in special,
+                                             view[pos:]))
+        if symbol:
+            yield ('symbol', symbol, pos)
+            pos += len(symbol)
+        else: # special char, ignore space
+            if text[pos] != ' ':
+                yield (text[pos], None, pos)
+            pos += 1
+    yield ('end', None, pos)
+
+def _parse(text):
+    tree, pos = parser.parser(_elements).parse(_tokenize(text))
+    if pos != len(text):
+        raise error.ParseError('invalid token', pos)
+    return tree
+
+def _parsedrev(symbol):
+    """str -> int or None, ex. 'D45' -> 45; '12' -> 12; 'x' -> None"""
+    if symbol.startswith('D') and symbol[1:].isdigit():
+        return int(symbol[1:])
+    if symbol.isdigit():
+        return int(symbol)
+
+def _prefetchdrevs(tree):
+    """return ({single-drev-id}, {ancestor-drev-id}) to prefetch"""
+    drevs = set()
+    ancestordrevs = set()
+    op = tree[0]
+    if op == 'symbol':
+        r = _parsedrev(tree[1])
+        if r:
+            drevs.add(r)
+    elif op == 'ancestors':
+        r, a = _prefetchdrevs(tree[1])
+        drevs.update(r)
+        ancestordrevs.update(r)
+        ancestordrevs.update(a)
+    else:
+        for t in tree[1:]:
+            r, a = _prefetchdrevs(t)
+            drevs.update(r)
+            ancestordrevs.update(a)
+    return drevs, ancestordrevs
+
+def querydrev(repo, spec):
+    """return a list of "Differential Revision" dicts
+
+    spec is a string using a simple query language, see docstring in phabread
+    for details.
+
+    A "Differential Revision dict" looks like:
+
+        {
+            "id": "2",
+            "phid": "PHID-DREV-672qvysjcczopag46qty",
+            "title": "example",
+            "uri": "https://phab.example.com/D2",
+            "dateCreated": "1499181406",
+            "dateModified": "1499182103",
+            "authorPHID": "PHID-USER-tv3ohwc4v4jeu34otlye",
+            "status": "0",
+            "statusName": "Needs Review",
+            "properties": [],
+            "branch": null,
+            "summary": "",
+            "testPlan": "",
+            "lineCount": "2",
+            "activeDiffPHID": "PHID-DIFF-xoqnjkobbm6k4dk6hi72",
+            "diffs": [
+              "3",
+              "4",
+            ],
+            "commits": [],
+            "reviewers": [],
+            "ccs": [],
+            "hashes": [],
+            "auxiliary": {
+              "phabricator:projects": [],
+              "phabricator:depends-on": [
+                "PHID-DREV-gbapp366kutjebt7agcd"
+              ]
+            },
+            "repositoryPHID": "PHID-REPO-hub2hx62ieuqeheznasv",
+            "sourcePath": null
+        }
+    """
+    def fetch(params):
+        """params -> single drev or None"""
+        key = (params.get(r'ids') or params.get(r'phids') or [None])[0]
+        if key in prefetched:
+            return prefetched[key]
+        drevs = callconduit(repo, 'differential.query', params)
+        # Fill prefetched with the result
+        for drev in drevs:
+            prefetched[drev[r'phid']] = drev
+            prefetched[int(drev[r'id'])] = drev
+        if key not in prefetched:
+            raise error.Abort(_('cannot get Differential Revision %r') % params)
+        return prefetched[key]
+
+    def getstack(topdrevids):
+        """given a top, get a stack from the bottom, [id] -> [id]"""
+        visited = set()
+        result = []
+        queue = [{r'ids': [i]} for i in topdrevids]
+        while queue:
+            params = queue.pop()
+            drev = fetch(params)
+            if drev[r'id'] in visited:
+                continue
+            visited.add(drev[r'id'])
+            result.append(int(drev[r'id']))
+            auxiliary = drev.get(r'auxiliary', {})
+            depends = auxiliary.get(r'phabricator:depends-on', [])
+            for phid in depends:
+                queue.append({'phids': [phid]})
+        result.reverse()
+        return smartset.baseset(result)
+
+    # Initialize prefetch cache
+    prefetched = {} # {id or phid: drev}
+
+    tree = _parse(spec)
+    drevs, ancestordrevs = _prefetchdrevs(tree)
+
+    # developer config: phabricator.batchsize
+    batchsize = repo.ui.configint('phabricator', 'batchsize', 12)
+
+    # Prefetch Differential Revisions in batch
+    tofetch = set(drevs)
+    for r in ancestordrevs:
+        tofetch.update(range(max(1, r - batchsize), r + 1))
+    if drevs:
+        fetch({r'ids': list(tofetch)})
+    validids = sorted(set(getstack(list(ancestordrevs))) | set(drevs))
+
+    # Walk through the tree, return smartsets
+    def walk(tree):
+        op = tree[0]
+        if op == 'symbol':
+            drev = _parsedrev(tree[1])
+            if drev:
+                return smartset.baseset([drev])
+            elif tree[1] in _knownstatusnames:
+                drevs = [r for r in validids
+                         if _getstatusname(prefetched[r]) == tree[1]]
+                return smartset.baseset(drevs)
+            else:
+                raise error.Abort(_('unknown symbol: %s') % tree[1])
+        elif op in {'and_', 'add', 'sub'}:
+            assert(len(tree) == 3)
+            return getattr(operator, op)(walk(tree[1]), walk(tree[2]))
+        elif op == 'group':
+            return walk(tree[1])
+        elif op == 'ancestors':
+            return getstack(walk(tree[1]))
+        else:
+            raise error.ProgrammingError('illegal tree: %r' % tree)
+
+    return [prefetched[r] for r in walk(tree)]
+
+def getdescfromdrev(drev):
+    """get description (commit message) from "Differential Revision"
+
+    This is similar to differential.getcommitmessage API. But we only care
+    about limited fields: title, summary, test plan, and URL.
+    """
+    title = drev[r'title']
+    summary = drev[r'summary'].rstrip()
+    testplan = drev[r'testPlan'].rstrip()
+    if testplan:
+        testplan = 'Test Plan:\n%s' % testplan
+    uri = 'Differential Revision: %s' % drev[r'uri']
+    return '\n\n'.join(filter(None, [title, summary, testplan, uri]))
+
+def getdiffmeta(diff):
+    """get commit metadata (date, node, user, p1) from a diff object
+
+    The metadata could be "hg:meta", sent by phabsend, like:
+
+        "properties": {
+          "hg:meta": {
+            "date": "1499571514 25200",
+            "node": "98c08acae292b2faf60a279b4189beb6cff1414d",
+            "user": "Foo Bar <foo@example.com>",
+            "parent": "6d0abad76b30e4724a37ab8721d630394070fe16"
+          }
+        }
+
+    Or converted from "local:commits", sent by "arc", like:
+
+        "properties": {
+          "local:commits": {
+            "98c08acae292b2faf60a279b4189beb6cff1414d": {
+              "author": "Foo Bar",
+              "time": 1499546314,
+              "branch": "default",
+              "tag": "",
+              "commit": "98c08acae292b2faf60a279b4189beb6cff1414d",
+              "rev": "98c08acae292b2faf60a279b4189beb6cff1414d",
+              "local": "1000",
+              "parents": ["6d0abad76b30e4724a37ab8721d630394070fe16"],
+              "summary": "...",
+              "message": "...",
+              "authorEmail": "foo@example.com"
+            }
+          }
+        }
+
+    Note: metadata extracted from "local:commits" will lose time zone
+    information.
+    """
+    props = diff.get(r'properties') or {}
+    meta = props.get(r'hg:meta')
+    if not meta and props.get(r'local:commits'):
+        commit = sorted(props[r'local:commits'].values())[0]
+        meta = {
+            r'date': r'%d 0' % commit[r'time'],
+            r'node': commit[r'rev'],
+            r'user': r'%s <%s>' % (commit[r'author'], commit[r'authorEmail']),
+        }
+        if len(commit.get(r'parents', ())) >= 1:
+            meta[r'parent'] = commit[r'parents'][0]
+    return meta or {}
+
+def readpatch(repo, drevs, write):
+    """generate plain-text patch readable by 'hg import'
+
+    write is usually ui.write. drevs is what "querydrev" returns, results of
+    "differential.query".
+    """
+    # Prefetch hg:meta property for all diffs
+    diffids = sorted(set(max(int(v) for v in drev[r'diffs']) for drev in drevs))
+    diffs = callconduit(repo, 'differential.querydiffs', {'ids': diffids})
+
+    # Generate patch for each drev
+    for drev in drevs:
+        repo.ui.note(_('reading D%s\n') % drev[r'id'])
+
+        diffid = max(int(v) for v in drev[r'diffs'])
+        body = callconduit(repo, 'differential.getrawdiff', {'diffID': diffid})
+        desc = getdescfromdrev(drev)
+        header = '# HG changeset patch\n'
+
+        # Try to preserve metadata from hg:meta property. Write hg patch
+        # headers that can be read by the "import" command. See patchheadermap
+        # and extract in mercurial/patch.py for supported headers.
+        meta = getdiffmeta(diffs[str(diffid)])
+        for k in _metanamemap.keys():
+            if k in meta:
+                header += '# %s %s\n' % (_metanamemap[k], meta[k])
+
+        write(('%s%s\n%s') % (header, desc, body))
+
+@command('phabread',
+         [('', 'stack', False, _('read dependencies'))],
+         _('DREVSPEC [OPTIONS]'))
+def phabread(ui, repo, spec, **opts):
+    """print patches from Phabricator suitable for importing
+
+    DREVSPEC could be a Differential Revision identity, like ``D123``, or just
+    the number ``123``. It could also have common operators like ``+``, ``-``,
+    ``&``, ``(``, ``)`` for complex queries. Prefix ``:`` could be used to
+    select a stack.
+
+    ``abandoned``, ``accepted``, ``closed``, ``needsreview``, ``needsrevision``
+    could be used to filter patches by status. For performance reason, they
+    only represent a subset of non-status selections and cannot be used alone.
+
+    For example, ``:D6+8-(2+D4)`` selects a stack up to D6, plus D8 and exclude
+    D2 and D4. ``:D9 & needsreview`` selects "Needs Review" revisions in a
+    stack up to D9.
+
+    If --stack is given, follow dependencies information and read all patches.
+    It is equivalent to the ``:`` operator.
+    """
+    if opts.get('stack'):
+        spec = ':(%s)' % spec
+    drevs = querydrev(repo, spec)
+    readpatch(repo, drevs, ui.write)
+
+@command('phabupdate',
+         [('', 'accept', False, _('accept revisions')),
+          ('', 'reject', False, _('reject revisions')),
+          ('', 'abandon', False, _('abandon revisions')),
+          ('', 'reclaim', False, _('reclaim revisions')),
+          ('m', 'comment', '', _('comment on the last revision')),
+         ], _('DREVSPEC [OPTIONS]'))
+def phabupdate(ui, repo, spec, **opts):
+    """update Differential Revision in batch
+
+    DREVSPEC selects revisions. See :hg:`help phabread` for its usage.
+    """
+    flags = [n for n in 'accept reject abandon reclaim'.split() if opts.get(n)]
+    if len(flags) > 1:
+        raise error.Abort(_('%s cannot be used together') % ', '.join(flags))
+
+    actions = []
+    for f in flags:
+        actions.append({'type': f, 'value': 'true'})
+
+    drevs = querydrev(repo, spec)
+    for i, drev in enumerate(drevs):
+        if i + 1 == len(drevs) and opts.get('comment'):
+            actions.append({'type': 'comment', 'value': opts['comment']})
+        if actions:
+            params = {'objectIdentifier': drev[r'phid'],
+                      'transactions': actions}
+            callconduit(repo, 'differential.revision.edit', params)